OSCL-LXR linux-6.0.1/​net/​core/​dev.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *      NET3    Protocol independent device support routines.
  *
  *  Derived from the non IP parts of dev.c 1.0.19
  *              Authors:    Ross Biro
  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  *              Mark Evans, <evansmp@uhura.aston.ac.uk>
  *
  *  Additional Authors:
  *      Florian la Roche <rzsfl@rz.uni-sb.de>
  *      Alan Cox <gw4pts@gw4pts.ampr.org>
  *      David Hinds <dahinds@users.sourceforge.net>
  *      Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
  *      Adam Sulmicki <adam@cfar.umd.edu>
  *              Pekka Riikonen <priikone@poesidon.pspt.fi>
  *
  *  Changes:
  *              D.J. Barrow     :       Fixed bug where dev->refcnt gets set
  *                                      to 2 if register_netdev gets called
  *                                      before net_dev_init & also removed a
  *                                      few lines of code in the process.
  *      Alan Cox    :   device private ioctl copies fields back.
  *      Alan Cox    :   Transmit queue code does relevant
  *                  stunts to keep the queue safe.
  *      Alan Cox    :   Fixed double lock.
  *      Alan Cox    :   Fixed promisc NULL pointer trap
  *      ????????    :   Support the full private ioctl range
  *      Alan Cox    :   Moved ioctl permission check into
  *                  drivers
  *      Tim Kordas  :   SIOCADDMULTI/SIOCDELMULTI
  *      Alan Cox    :   100 backlog just doesn't cut it when
  *                  you start doing multicast video 8)
  *      Alan Cox    :   Rewrote net_bh and list manager.
  *              Alan Cox        :       Fix ETH_P_ALL echoback lengths.
  *      Alan Cox    :   Took out transmit every packet pass
  *                  Saved a few bytes in the ioctl handler
  *      Alan Cox    :   Network driver sets packet type before
  *                  calling netif_rx. Saves a function
  *                  call a packet.
  *      Alan Cox    :   Hashed net_bh()
  *      Richard Kooijman:   Timestamp fixes.
  *      Alan Cox    :   Wrong field in SIOCGIFDSTADDR
  *      Alan Cox    :   Device lock protection.
  *              Alan Cox        :       Fixed nasty side effect of device close
  *                  changes.
  *      Rudi Cilibrasi  :   Pass the right thing to
  *                  set_mac_address()
  *      Dave Miller :   32bit quantity for the device lock to
  *                  make it work out on a Sparc.
  *      Bjorn Ekwall    :   Added KERNELD hack.
  *      Alan Cox    :   Cleaned up the backlog initialise.
  *      Craig Metz  :   SIOCGIFCONF fix if space for under
  *                  1 device.
  *      Thomas Bogendoerfer :   Return ENODEV for dev_open, if there
  *                  is no device open function.
  *      Andi Kleen  :   Fix error reporting for SIOCGIFCONF
  *      Michael Chastain    :   Fix signed/unsigned for SIOCGIFCONF
  *      Cyrus Durgin    :   Cleaned for KMOD
  *      Adam Sulmicki   :   Bug Fix : Network Device Unload
  *                  A network device unload needs to purge
  *                  the backlog queue.
  *  Paul Rusty Russell  :   SIOCSIFNAME
  *              Pekka Riikonen  :   Netdev boot-time settings code
  *              Andrew Morton   :       Make unregister_netdevice wait
  *                                      indefinitely on dev->refcnt
  *              J Hadi Salim    :       - Backlog queue sampling
  *                      - netif_rx() feedback
  */
 
 #include <linux/uaccess.h>
 #include <linux/bitops.h>
 #include <linux/capability.h>
 #include <linux/cpu.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/hash.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/sched/mm.h>
 #include <linux/mutex.h>
 #include <linux/rwsem.h>
 #include <linux/string.h>
 #include <linux/mm.h>
 #include <linux/socket.h>
 #include <linux/sockios.h>
 #include <linux/errno.h>
 #include <linux/interrupt.h>
 #include <linux/if_ether.h>
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/ethtool.h>
 #include <linux/skbuff.h>
 #include <linux/kthread.h>
 #include <linux/bpf.h>
 #include <linux/bpf_trace.h>
 #include <net/net_namespace.h>
 #include <net/sock.h>
 #include <net/busy_poll.h>
 #include <linux/rtnetlink.h>
 #include <linux/stat.h>
 #include <net/dsa.h>
 #include <net/dst.h>
 #include <net/dst_metadata.h>
 #include <net/gro.h>
 #include <net/pkt_sched.h>
 #include <net/pkt_cls.h>
 #include <net/checksum.h>
 #include <net/xfrm.h>
 #include <linux/highmem.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/netpoll.h>
 #include <linux/rcupdate.h>
 #include <linux/delay.h>
 #include <net/iw_handler.h>
 #include <asm/current.h>
 #include <linux/audit.h>
 #include <linux/dmaengine.h>
 #include <linux/err.h>
 #include <linux/ctype.h>
 #include <linux/if_arp.h>
 #include <linux/if_vlan.h>
 #include <linux/ip.h>
 #include <net/ip.h>
 #include <net/mpls.h>
 #include <linux/ipv6.h>
 #include <linux/in.h>
 #include <linux/jhash.h>
 #include <linux/random.h>
 #include <trace/events/napi.h>
 #include <trace/events/net.h>
 #include <trace/events/skb.h>
 #include <trace/events/qdisc.h>
 #include <linux/inetdevice.h>
 #include <linux/cpu_rmap.h>
 #include <linux/static_key.h>
 #include <linux/hashtable.h>
 #include <linux/vmalloc.h>
 #include <linux/if_macvlan.h>
 #include <linux/errqueue.h>
 #include <linux/hrtimer.h>
 #include <linux/netfilter_netdev.h>
 #include <linux/crash_dump.h>
 #include <linux/sctp.h>
 #include <net/udp_tunnel.h>
 #include <linux/net_namespace.h>
 #include <linux/indirect_call_wrapper.h>
 #include <net/devlink.h>
 #include <linux/pm_runtime.h>
 #include <linux/prandom.h>
 #include <linux/once_lite.h>
 
 #include "dev.h"
 #include "net-sysfs.h"
 
 
 static DEFINE_SPINLOCK(ptype_lock);
 struct list_head ptype_base[PTYPE_HASH_SIZE] __read_mostly;
 struct list_head ptype_all __read_mostly;   /* Taps */
 
 static int netif_rx_internal(struct sk_buff *skb);
 static int call_netdevice_notifiers_info(unsigned long val,
                      struct netdev_notifier_info *info);
 static int call_netdevice_notifiers_extack(unsigned long val,
                        struct net_device *dev,
                        struct netlink_ext_ack *extack);
 static struct napi_struct *napi_by_id(unsigned int napi_id);
 
 /*
  * The @dev_base_head list is protected by @dev_base_lock and the rtnl
  * semaphore.
  *
  * Pure readers hold dev_base_lock for reading, or rcu_read_lock()
  *
  * Writers must hold the rtnl semaphore while they loop through the
  * dev_base_head list, and hold dev_base_lock for writing when they do the
  * actual updates.  This allows pure readers to access the list even
  * while a writer is preparing to update it.
  *
  * To put it another way, dev_base_lock is held for writing only to
  * protect against pure readers; the rtnl semaphore provides the
  * protection against other writers.
  *
  * See, for example usages, register_netdevice() and
  * unregister_netdevice(), which must be called with the rtnl
  * semaphore held.
  */
 DEFINE_RWLOCK(dev_base_lock);
 EXPORT_SYMBOL(dev_base_lock);
 
 static DEFINE_MUTEX(ifalias_mutex);
 
 /* protects napi_hash addition/deletion and napi_gen_id */
 static DEFINE_SPINLOCK(napi_hash_lock);
 
 static unsigned int napi_gen_id = NR_CPUS;
 static DEFINE_READ_MOSTLY_HASHTABLE(napi_hash, 8);
 
 static DECLARE_RWSEM(devnet_rename_sem);
 
 static inline void dev_base_seq_inc(struct net *net)
 {
     while (++net->dev_base_seq == 0)
         ;
 }
 
 static inline struct hlist_head *dev_name_hash(struct net *net, const char *name)
 {
     unsigned int hash = full_name_hash(net, name, strnlen(name, IFNAMSIZ));
 
     return &net->dev_name_head[hash_32(hash, NETDEV_HASHBITS)];
 }
 
 static inline struct hlist_head *dev_index_hash(struct net *net, int ifindex)
 {
     return &net->dev_index_head[ifindex & (NETDEV_HASHENTRIES - 1)];
 }
 
 static inline void rps_lock_irqsave(struct softnet_data *sd,
                     unsigned long *flags)
 {
     if (IS_ENABLED(CONFIG_RPS))
         spin_lock_irqsave(&sd->input_pkt_queue.lock, *flags);
     else if (!IS_ENABLED(CONFIG_PREEMPT_RT))
         local_irq_save(*flags);
 }
 
 static inline void rps_lock_irq_disable(struct softnet_data *sd)
 {
     if (IS_ENABLED(CONFIG_RPS))
         spin_lock_irq(&sd->input_pkt_queue.lock);
     else if (!IS_ENABLED(CONFIG_PREEMPT_RT))
         local_irq_disable();
 }
 
 static inline void rps_unlock_irq_restore(struct softnet_data *sd,
                       unsigned long *flags)
 {
     if (IS_ENABLED(CONFIG_RPS))
         spin_unlock_irqrestore(&sd->input_pkt_queue.lock, *flags);
     else if (!IS_ENABLED(CONFIG_PREEMPT_RT))
         local_irq_restore(*flags);
 }
 
 static inline void rps_unlock_irq_enable(struct softnet_data *sd)
 {
     if (IS_ENABLED(CONFIG_RPS))
         spin_unlock_irq(&sd->input_pkt_queue.lock);
     else if (!IS_ENABLED(CONFIG_PREEMPT_RT))
         local_irq_enable();
 }
 
 static struct netdev_name_node *netdev_name_node_alloc(struct net_device *dev,
                                const char *name)
 {
     struct netdev_name_node *name_node;
 
     name_node = kmalloc(sizeof(*name_node), GFP_KERNEL);
     if (!name_node)
         return NULL;
     INIT_HLIST_NODE(&name_node->hlist);
     name_node->dev = dev;
     name_node->name = name;
     return name_node;
 }
 
 static struct netdev_name_node *
 netdev_name_node_head_alloc(struct net_device *dev)
 {
     struct netdev_name_node *name_node;
 
     name_node = netdev_name_node_alloc(dev, dev->name);
     if (!name_node)
         return NULL;
     INIT_LIST_HEAD(&name_node->list);
     return name_node;
 }
 
 static void netdev_name_node_free(struct netdev_name_node *name_node)
 {
     kfree(name_node);
 }
 
 static void netdev_name_node_add(struct net *net,
                  struct netdev_name_node *name_node)
 {
     hlist_add_head_rcu(&name_node->hlist,
                dev_name_hash(net, name_node->name));
 }
 
 static void netdev_name_node_del(struct netdev_name_node *name_node)
 {
     hlist_del_rcu(&name_node->hlist);
 }
 
 static struct netdev_name_node *netdev_name_node_lookup(struct net *net,
                             const char *name)
 {
     struct hlist_head *head = dev_name_hash(net, name);
     struct netdev_name_node *name_node;
 
     hlist_for_each_entry(name_node, head, hlist)
         if (!strcmp(name_node->name, name))
             return name_node;
     return NULL;
 }
 
 static struct netdev_name_node *netdev_name_node_lookup_rcu(struct net *net,
                                 const char *name)
 {
     struct hlist_head *head = dev_name_hash(net, name);
     struct netdev_name_node *name_node;
 
     hlist_for_each_entry_rcu(name_node, head, hlist)
         if (!strcmp(name_node->name, name))
             return name_node;
     return NULL;
 }
 
 bool netdev_name_in_use(struct net *net, const char *name)
 {
     return netdev_name_node_lookup(net, name);
 }
 EXPORT_SYMBOL(netdev_name_in_use);
 
 int netdev_name_node_alt_create(struct net_device *dev, const char *name)
 {
     struct netdev_name_node *name_node;
     struct net *net = dev_net(dev);
 
     name_node = netdev_name_node_lookup(net, name);
     if (name_node)
         return -EEXIST;
     name_node = netdev_name_node_alloc(dev, name);
     if (!name_node)
         return -ENOMEM;
     netdev_name_node_add(net, name_node);
     /* The node that holds dev->name acts as a head of per-device list. */
     list_add_tail(&name_node->list, &dev->name_node->list);
 
     return 0;
 }
 
 static void __netdev_name_node_alt_destroy(struct netdev_name_node *name_node)
 {
     list_del(&name_node->list);
     netdev_name_node_del(name_node);
     kfree(name_node->name);
     netdev_name_node_free(name_node);
 }
 
 int netdev_name_node_alt_destroy(struct net_device *dev, const char *name)
 {
     struct netdev_name_node *name_node;
     struct net *net = dev_net(dev);
 
     name_node = netdev_name_node_lookup(net, name);
     if (!name_node)
         return -ENOENT;
     /* lookup might have found our primary name or a name belonging
      * to another device.
      */
     if (name_node == dev->name_node || name_node->dev != dev)
         return -EINVAL;
 
     __netdev_name_node_alt_destroy(name_node);
 
     return 0;
 }
 
 static void netdev_name_node_alt_flush(struct net_device *dev)
 {
     struct netdev_name_node *name_node, *tmp;
 
     list_for_each_entry_safe(name_node, tmp, &dev->name_node->list, list)
         __netdev_name_node_alt_destroy(name_node);
 }
 
 /* Device list insertion */
 static void list_netdevice(struct net_device *dev)
 {
     struct net *net = dev_net(dev);
 
     ASSERT_RTNL();
 
     write_lock(&dev_base_lock);
     list_add_tail_rcu(&dev->dev_list, &net->dev_base_head);
     netdev_name_node_add(net, dev->name_node);
     hlist_add_head_rcu(&dev->index_hlist,
                dev_index_hash(net, dev->ifindex));
     write_unlock(&dev_base_lock);
 
     dev_base_seq_inc(net);
 }
 
 /* Device list removal
  * caller must respect a RCU grace period before freeing/reusing dev
  */
 static void unlist_netdevice(struct net_device *dev, bool lock)
 {
     ASSERT_RTNL();
 
     /* Unlink dev from the device chain */
     if (lock)
         write_lock(&dev_base_lock);
     list_del_rcu(&dev->dev_list);
     netdev_name_node_del(dev->name_node);
     hlist_del_rcu(&dev->index_hlist);
     if (lock)
         write_unlock(&dev_base_lock);
 
     dev_base_seq_inc(dev_net(dev));
 }
 
 /*
  *  Our notifier list
  */
 
 static RAW_NOTIFIER_HEAD(netdev_chain);
 
 /*
  *  Device drivers call our routines to queue packets here. We empty the
  *  queue in the local softnet handler.
  */
 
 DEFINE_PER_CPU_ALIGNED(struct softnet_data, softnet_data);
 EXPORT_PER_CPU_SYMBOL(softnet_data);
 
 #ifdef CONFIG_LOCKDEP
 /*
  * register_netdevice() inits txq->_xmit_lock and sets lockdep class
  * according to dev->type
  */
 static const unsigned short netdev_lock_type[] = {
      ARPHRD_NETROM, ARPHRD_ETHER, ARPHRD_EETHER, ARPHRD_AX25,
      ARPHRD_PRONET, ARPHRD_CHAOS, ARPHRD_IEEE802, ARPHRD_ARCNET,
      ARPHRD_APPLETLK, ARPHRD_DLCI, ARPHRD_ATM, ARPHRD_METRICOM,
      ARPHRD_IEEE1394, ARPHRD_EUI64, ARPHRD_INFINIBAND, ARPHRD_SLIP,
      ARPHRD_CSLIP, ARPHRD_SLIP6, ARPHRD_CSLIP6, ARPHRD_RSRVD,
      ARPHRD_ADAPT, ARPHRD_ROSE, ARPHRD_X25, ARPHRD_HWX25,
      ARPHRD_PPP, ARPHRD_CISCO, ARPHRD_LAPB, ARPHRD_DDCMP,
      ARPHRD_RAWHDLC, ARPHRD_TUNNEL, ARPHRD_TUNNEL6, ARPHRD_FRAD,
      ARPHRD_SKIP, ARPHRD_LOOPBACK, ARPHRD_LOCALTLK, ARPHRD_FDDI,
      ARPHRD_BIF, ARPHRD_SIT, ARPHRD_IPDDP, ARPHRD_IPGRE,
      ARPHRD_PIMREG, ARPHRD_HIPPI, ARPHRD_ASH, ARPHRD_ECONET,
      ARPHRD_IRDA, ARPHRD_FCPP, ARPHRD_FCAL, ARPHRD_FCPL,
      ARPHRD_FCFABRIC, ARPHRD_IEEE80211, ARPHRD_IEEE80211_PRISM,
      ARPHRD_IEEE80211_RADIOTAP, ARPHRD_PHONET, ARPHRD_PHONET_PIPE,
      ARPHRD_IEEE802154, ARPHRD_VOID, ARPHRD_NONE};
 
 static const char *const netdev_lock_name[] = {
     "_xmit_NETROM", "_xmit_ETHER", "_xmit_EETHER", "_xmit_AX25",
     "_xmit_PRONET", "_xmit_CHAOS", "_xmit_IEEE802", "_xmit_ARCNET",
     "_xmit_APPLETLK", "_xmit_DLCI", "_xmit_ATM", "_xmit_METRICOM",
     "_xmit_IEEE1394", "_xmit_EUI64", "_xmit_INFINIBAND", "_xmit_SLIP",
     "_xmit_CSLIP", "_xmit_SLIP6", "_xmit_CSLIP6", "_xmit_RSRVD",
     "_xmit_ADAPT", "_xmit_ROSE", "_xmit_X25", "_xmit_HWX25",
     "_xmit_PPP", "_xmit_CISCO", "_xmit_LAPB", "_xmit_DDCMP",
     "_xmit_RAWHDLC", "_xmit_TUNNEL", "_xmit_TUNNEL6", "_xmit_FRAD",
     "_xmit_SKIP", "_xmit_LOOPBACK", "_xmit_LOCALTLK", "_xmit_FDDI",
     "_xmit_BIF", "_xmit_SIT", "_xmit_IPDDP", "_xmit_IPGRE",
     "_xmit_PIMREG", "_xmit_HIPPI", "_xmit_ASH", "_xmit_ECONET",
     "_xmit_IRDA", "_xmit_FCPP", "_xmit_FCAL", "_xmit_FCPL",
     "_xmit_FCFABRIC", "_xmit_IEEE80211", "_xmit_IEEE80211_PRISM",
     "_xmit_IEEE80211_RADIOTAP", "_xmit_PHONET", "_xmit_PHONET_PIPE",
     "_xmit_IEEE802154", "_xmit_VOID", "_xmit_NONE"};
 
 static struct lock_class_key netdev_xmit_lock_key[ARRAY_SIZE(netdev_lock_type)];
 static struct lock_class_key netdev_addr_lock_key[ARRAY_SIZE(netdev_lock_type)];
 
 static inline unsigned short netdev_lock_pos(unsigned short dev_type)
 {
     int i;
 
     for (i = 0; i < ARRAY_SIZE(netdev_lock_type); i++)
         if (netdev_lock_type[i] == dev_type)
             return i;
     /* the last key is used by default */
     return ARRAY_SIZE(netdev_lock_type) - 1;
 }
 
 static inline void netdev_set_xmit_lockdep_class(spinlock_t *lock,
                          unsigned short dev_type)
 {
     int i;
 
     i = netdev_lock_pos(dev_type);
     lockdep_set_class_and_name(lock, &netdev_xmit_lock_key[i],
                    netdev_lock_name[i]);
 }
 
 static inline void netdev_set_addr_lockdep_class(struct net_device *dev)
 {
     int i;
 
     i = netdev_lock_pos(dev->type);
     lockdep_set_class_and_name(&dev->addr_list_lock,
                    &netdev_addr_lock_key[i],
                    netdev_lock_name[i]);
 }
 #else
 static inline void netdev_set_xmit_lockdep_class(spinlock_t *lock,
                          unsigned short dev_type)
 {
 }
 
 static inline void netdev_set_addr_lockdep_class(struct net_device *dev)
 {
 }
 #endif
 
 /*******************************************************************************
  *
  *      Protocol management and registration routines
  *
  *******************************************************************************/
 
 
 /*
  *  Add a protocol ID to the list. Now that the input handler is
  *  smarter we can dispense with all the messy stuff that used to be
  *  here.
  *
  *  BEWARE!!! Protocol handlers, mangling input packets,
  *  MUST BE last in hash buckets and checking protocol handlers
  *  MUST start from promiscuous ptype_all chain in net_bh.
  *  It is true now, do not change it.
  *  Explanation follows: if protocol handler, mangling packet, will
  *  be the first on list, it is not able to sense, that packet
  *  is cloned and should be copied-on-write, so that it will
  *  change it and subsequent readers will get broken packet.
  *                          --ANK (980803)
  */
 
 static inline struct list_head *ptype_head(const struct packet_type *pt)
 {
     if (pt->type == htons(ETH_P_ALL))
         return pt->dev ? &pt->dev->ptype_all : &ptype_all;
     else
         return pt->dev ? &pt->dev->ptype_specific :
                  &ptype_base[ntohs(pt->type) & PTYPE_HASH_MASK];
 }
 
 /**
  *  dev_add_pack - add packet handler
  *  @pt: packet type declaration
  *
  *  Add a protocol handler to the networking stack. The passed &packet_type
  *  is linked into kernel lists and may not be freed until it has been
  *  removed from the kernel lists.
  *
  *  This call does not sleep therefore it can not
  *  guarantee all CPU's that are in middle of receiving packets
  *  will see the new packet type (until the next received packet).
  */
 
 void dev_add_pack(struct packet_type *pt)
 {
     struct list_head *head = ptype_head(pt);
 
     spin_lock(&ptype_lock);
     list_add_rcu(&pt->list, head);
     spin_unlock(&ptype_lock);
 }
 EXPORT_SYMBOL(dev_add_pack);
 
 /**
  *  __dev_remove_pack    - remove packet handler
  *  @pt: packet type declaration
  *
  *  Remove a protocol handler that was previously added to the kernel
  *  protocol handlers by dev_add_pack(). The passed &packet_type is removed
  *  from the kernel lists and can be freed or reused once this function
  *  returns.
  *
  *      The packet type might still be in use by receivers
  *  and must not be freed until after all the CPU's have gone
  *  through a quiescent state.
  */
 void __dev_remove_pack(struct packet_type *pt)
 {
     struct list_head *head = ptype_head(pt);
     struct packet_type *pt1;
 
     spin_lock(&ptype_lock);
 
     list_for_each_entry(pt1, head, list) {
         if (pt == pt1) {
             list_del_rcu(&pt->list);
             goto out;
         }
     }
 
     pr_warn("dev_remove_pack: %p not found\n", pt);
 out:
     spin_unlock(&ptype_lock);
 }
 EXPORT_SYMBOL(__dev_remove_pack);
 
 /**
  *  dev_remove_pack  - remove packet handler
  *  @pt: packet type declaration
  *
  *  Remove a protocol handler that was previously added to the kernel
  *  protocol handlers by dev_add_pack(). The passed &packet_type is removed
  *  from the kernel lists and can be freed or reused once this function
  *  returns.
  *
  *  This call sleeps to guarantee that no CPU is looking at the packet
  *  type after return.
  */
 void dev_remove_pack(struct packet_type *pt)
 {
     __dev_remove_pack(pt);
 
     synchronize_net();
 }
 EXPORT_SYMBOL(dev_remove_pack);
 
 
 /*******************************************************************************
  *
  *              Device Interface Subroutines
  *
  *******************************************************************************/
 
 /**
  *  dev_get_iflink  - get 'iflink' value of a interface
  *  @dev: targeted interface
  *
  *  Indicates the ifindex the interface is linked to.
  *  Physical interfaces have the same 'ifindex' and 'iflink' values.
  */
 
 int dev_get_iflink(const struct net_device *dev)
 {
     if (dev->netdev_ops && dev->netdev_ops->ndo_get_iflink)
         return dev->netdev_ops->ndo_get_iflink(dev);
 
     return dev->ifindex;
 }
 EXPORT_SYMBOL(dev_get_iflink);
 
 /**
  *  dev_fill_metadata_dst - Retrieve tunnel egress information.
  *  @dev: targeted interface
  *  @skb: The packet.
  *
  *  For better visibility of tunnel traffic OVS needs to retrieve
  *  egress tunnel information for a packet. Following API allows
  *  user to get this info.
  */
 int dev_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb)
 {
     struct ip_tunnel_info *info;
 
     if (!dev->netdev_ops  || !dev->netdev_ops->ndo_fill_metadata_dst)
         return -EINVAL;
 
     info = skb_tunnel_info_unclone(skb);
     if (!info)
         return -ENOMEM;
     if (unlikely(!(info->mode & IP_TUNNEL_INFO_TX)))
         return -EINVAL;
 
     return dev->netdev_ops->ndo_fill_metadata_dst(dev, skb);
 }
 EXPORT_SYMBOL_GPL(dev_fill_metadata_dst);
 
 static struct net_device_path *dev_fwd_path(struct net_device_path_stack *stack)
 {
     int k = stack->num_paths++;
 
     if (WARN_ON_ONCE(k >= NET_DEVICE_PATH_STACK_MAX))
         return NULL;
 
     return &stack->path[k];
 }
 
 int dev_fill_forward_path(const struct net_device *dev, const u8 *daddr,
               struct net_device_path_stack *stack)
 {
     const struct net_device *last_dev;
     struct net_device_path_ctx ctx = {
         .dev    = dev,
     };
     struct net_device_path *path;
     int ret = 0;
 
     memcpy(ctx.daddr, daddr, sizeof(ctx.daddr));
     stack->num_paths = 0;
     while (ctx.dev && ctx.dev->netdev_ops->ndo_fill_forward_path) {
         last_dev = ctx.dev;
         path = dev_fwd_path(stack);
         if (!path)
             return -1;
 
         memset(path, 0, sizeof(struct net_device_path));
         ret = ctx.dev->netdev_ops->ndo_fill_forward_path(&ctx, path);
         if (ret < 0)
             return -1;
 
         if (WARN_ON_ONCE(last_dev == ctx.dev))
             return -1;
     }
 
     if (!ctx.dev)
         return ret;
 
     path = dev_fwd_path(stack);
     if (!path)
         return -1;
     path->type = DEV_PATH_ETHERNET;
     path->dev = ctx.dev;
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(dev_fill_forward_path);
 
 /**
  *  __dev_get_by_name   - find a device by its name
  *  @net: the applicable net namespace
  *  @name: name to find
  *
  *  Find an interface by name. Must be called under RTNL semaphore
  *  or @dev_base_lock. If the name is found a pointer to the device
  *  is returned. If the name is not found then %NULL is returned. The
  *  reference counters are not incremented so the caller must be
  *  careful with locks.
  */
 
 struct net_device *__dev_get_by_name(struct net *net, const char *name)
 {
     struct netdev_name_node *node_name;
 
     node_name = netdev_name_node_lookup(net, name);
     return node_name ? node_name->dev : NULL;
 }
 EXPORT_SYMBOL(__dev_get_by_name);
 
 /**
  * dev_get_by_name_rcu  - find a device by its name
  * @net: the applicable net namespace
  * @name: name to find
  *
  * Find an interface by name.
  * If the name is found a pointer to the device is returned.
  * If the name is not found then %NULL is returned.
  * The reference counters are not incremented so the caller must be
  * careful with locks. The caller must hold RCU lock.
  */
 
 struct net_device *dev_get_by_name_rcu(struct net *net, const char *name)
 {
     struct netdev_name_node *node_name;
 
     node_name = netdev_name_node_lookup_rcu(net, name);
     return node_name ? node_name->dev : NULL;
 }
 EXPORT_SYMBOL(dev_get_by_name_rcu);
 
 /**
  *  dev_get_by_name     - find a device by its name
  *  @net: the applicable net namespace
  *  @name: name to find
  *
  *  Find an interface by name. This can be called from any
  *  context and does its own locking. The returned handle has
  *  the usage count incremented and the caller must use dev_put() to
  *  release it when it is no longer needed. %NULL is returned if no
  *  matching device is found.
  */
 
 struct net_device *dev_get_by_name(struct net *net, const char *name)
 {
     struct net_device *dev;
 
     rcu_read_lock();
     dev = dev_get_by_name_rcu(net, name);
     dev_hold(dev);
     rcu_read_unlock();
     return dev;
 }
 EXPORT_SYMBOL(dev_get_by_name);
 
 /**
  *  __dev_get_by_index - find a device by its ifindex
  *  @net: the applicable net namespace
  *  @ifindex: index of device
  *
  *  Search for an interface by index. Returns %NULL if the device
  *  is not found or a pointer to the device. The device has not
  *  had its reference counter increased so the caller must be careful
  *  about locking. The caller must hold either the RTNL semaphore
  *  or @dev_base_lock.
  */
 
 struct net_device *__dev_get_by_index(struct net *net, int ifindex)
 {
     struct net_device *dev;
     struct hlist_head *head = dev_index_hash(net, ifindex);
 
     hlist_for_each_entry(dev, head, index_hlist)
         if (dev->ifindex == ifindex)
             return dev;
 
     return NULL;
 }
 EXPORT_SYMBOL(__dev_get_by_index);
 
 /**
  *  dev_get_by_index_rcu - find a device by its ifindex
  *  @net: the applicable net namespace
  *  @ifindex: index of device
  *
  *  Search for an interface by index. Returns %NULL if the device
  *  is not found or a pointer to the device. The device has not
  *  had its reference counter increased so the caller must be careful
  *  about locking. The caller must hold RCU lock.
  */
 
 struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex)
 {
     struct net_device *dev;
     struct hlist_head *head = dev_index_hash(net, ifindex);
 
     hlist_for_each_entry_rcu(dev, head, index_hlist)
         if (dev->ifindex == ifindex)
             return dev;
 
     return NULL;
 }
 EXPORT_SYMBOL(dev_get_by_index_rcu);
 
 
 /**
  *  dev_get_by_index - find a device by its ifindex
  *  @net: the applicable net namespace
  *  @ifindex: index of device
  *
  *  Search for an interface by index. Returns NULL if the device
  *  is not found or a pointer to the device. The device returned has
  *  had a reference added and the pointer is safe until the user calls
  *  dev_put to indicate they have finished with it.
  */
 
 struct net_device *dev_get_by_index(struct net *net, int ifindex)
 {
     struct net_device *dev;
 
     rcu_read_lock();
     dev = dev_get_by_index_rcu(net, ifindex);
     dev_hold(dev);
     rcu_read_unlock();
     return dev;
 }
 EXPORT_SYMBOL(dev_get_by_index);
 
 /**
  *  dev_get_by_napi_id - find a device by napi_id
  *  @napi_id: ID of the NAPI struct
  *
  *  Search for an interface by NAPI ID. Returns %NULL if the device
  *  is not found or a pointer to the device. The device has not had
  *  its reference counter increased so the caller must be careful
  *  about locking. The caller must hold RCU lock.
  */
 
 struct net_device *dev_get_by_napi_id(unsigned int napi_id)
 {
     struct napi_struct *napi;
 
     WARN_ON_ONCE(!rcu_read_lock_held());
 
     if (napi_id < MIN_NAPI_ID)
         return NULL;
 
     napi = napi_by_id(napi_id);
 
     return napi ? napi->dev : NULL;
 }
 EXPORT_SYMBOL(dev_get_by_napi_id);
 
 /**
  *  netdev_get_name - get a netdevice name, knowing its ifindex.
  *  @net: network namespace
  *  @name: a pointer to the buffer where the name will be stored.
  *  @ifindex: the ifindex of the interface to get the name from.
  */
 int netdev_get_name(struct net *net, char *name, int ifindex)
 {
     struct net_device *dev;
     int ret;
 
     down_read(&devnet_rename_sem);
     rcu_read_lock();
 
     dev = dev_get_by_index_rcu(net, ifindex);
     if (!dev) {
         ret = -ENODEV;
         goto out;
     }
 
     strcpy(name, dev->name);
 
     ret = 0;
 out:
     rcu_read_unlock();
     up_read(&devnet_rename_sem);
     return ret;
 }
 
 /**
  *  dev_getbyhwaddr_rcu - find a device by its hardware address
  *  @net: the applicable net namespace
  *  @type: media type of device
  *  @ha: hardware address
  *
  *  Search for an interface by MAC address. Returns NULL if the device
  *  is not found or a pointer to the device.
  *  The caller must hold RCU or RTNL.
  *  The returned device has not had its ref count increased
  *  and the caller must therefore be careful about locking
  *
  */
 
 struct net_device *dev_getbyhwaddr_rcu(struct net *net, unsigned short type,
                        const char *ha)
 {
     struct net_device *dev;
 
     for_each_netdev_rcu(net, dev)
         if (dev->type == type &&
             !memcmp(dev->dev_addr, ha, dev->addr_len))
             return dev;
 
     return NULL;
 }
 EXPORT_SYMBOL(dev_getbyhwaddr_rcu);
 
 struct net_device *dev_getfirstbyhwtype(struct net *net, unsigned short type)
 {
     struct net_device *dev, *ret = NULL;
 
     rcu_read_lock();
     for_each_netdev_rcu(net, dev)
         if (dev->type == type) {
             dev_hold(dev);
             ret = dev;
             break;
         }
     rcu_read_unlock();
     return ret;
 }
 EXPORT_SYMBOL(dev_getfirstbyhwtype);
 
 /**
  *  __dev_get_by_flags - find any device with given flags
  *  @net: the applicable net namespace
  *  @if_flags: IFF_* values
  *  @mask: bitmask of bits in if_flags to check
  *
  *  Search for any interface with the given flags. Returns NULL if a device
  *  is not found or a pointer to the device. Must be called inside
  *  rtnl_lock(), and result refcount is unchanged.
  */
 
 struct net_device *__dev_get_by_flags(struct net *net, unsigned short if_flags,
                       unsigned short mask)
 {
     struct net_device *dev, *ret;
 
     ASSERT_RTNL();
 
     ret = NULL;
     for_each_netdev(net, dev) {
         if (((dev->flags ^ if_flags) & mask) == 0) {
             ret = dev;
             break;
         }
     }
     return ret;
 }
 EXPORT_SYMBOL(__dev_get_by_flags);
 
 /**
  *  dev_valid_name - check if name is okay for network device
  *  @name: name string
  *
  *  Network device names need to be valid file names to
  *  allow sysfs to work.  We also disallow any kind of
  *  whitespace.
  */
 bool dev_valid_name(const char *name)
 {
     if (*name == '\0')
         return false;
     if (strnlen(name, IFNAMSIZ) == IFNAMSIZ)
         return false;
     if (!strcmp(name, ".") || !strcmp(name, ".."))
         return false;
 
     while (*name) {
         if (*name == '/' || *name == ':' || isspace(*name))
             return false;
         name++;
     }
     return true;
 }
 EXPORT_SYMBOL(dev_valid_name);
 
 /**
  *  __dev_alloc_name - allocate a name for a device
  *  @net: network namespace to allocate the device name in
  *  @name: name format string
  *  @buf:  scratch buffer and result name string
  *
  *  Passed a format string - eg "lt%d" it will try and find a suitable
  *  id. It scans list of devices to build up a free map, then chooses
  *  the first empty slot. The caller must hold the dev_base or rtnl lock
  *  while allocating the name and adding the device in order to avoid
  *  duplicates.
  *  Limited to bits_per_byte * page size devices (ie 32K on most platforms).
  *  Returns the number of the unit assigned or a negative errno code.
  */
 
 static int __dev_alloc_name(struct net *net, const char *name, char *buf)
 {
     int i = 0;
     const char *p;
     const int max_netdevices = 8*PAGE_SIZE;
     unsigned long *inuse;
     struct net_device *d;
 
     if (!dev_valid_name(name))
         return -EINVAL;
 
     p = strchr(name, '%');
     if (p) {
         /*
          * Verify the string as this thing may have come from
          * the user.  There must be either one "%d" and no other "%"
          * characters.
          */
         if (p[1] != 'd' || strchr(p + 2, '%'))
             return -EINVAL;
 
         /* Use one page as a bit array of possible slots */
         inuse = (unsigned long *) get_zeroed_page(GFP_ATOMIC);
         if (!inuse)
             return -ENOMEM;
 
         for_each_netdev(net, d) {
             struct netdev_name_node *name_node;
             list_for_each_entry(name_node, &d->name_node->list, list) {
                 if (!sscanf(name_node->name, name, &i))
                     continue;
                 if (i < 0 || i >= max_netdevices)
                     continue;
 
                 /*  avoid cases where sscanf is not exact inverse of printf */
                 snprintf(buf, IFNAMSIZ, name, i);
                 if (!strncmp(buf, name_node->name, IFNAMSIZ))
                     __set_bit(i, inuse);
             }
             if (!sscanf(d->name, name, &i))
                 continue;
             if (i < 0 || i >= max_netdevices)
                 continue;
 
             /*  avoid cases where sscanf is not exact inverse of printf */
             snprintf(buf, IFNAMSIZ, name, i);
             if (!strncmp(buf, d->name, IFNAMSIZ))
                 __set_bit(i, inuse);
         }
 
         i = find_first_zero_bit(inuse, max_netdevices);
         free_page((unsigned long) inuse);
     }
 
     snprintf(buf, IFNAMSIZ, name, i);
     if (!netdev_name_in_use(net, buf))
         return i;
 
     /* It is possible to run out of possible slots
      * when the name is long and there isn't enough space left
      * for the digits, or if all bits are used.
      */
     return -ENFILE;
 }
 
 static int dev_alloc_name_ns(struct net *net,
                  struct net_device *dev,
                  const char *name)
 {
     char buf[IFNAMSIZ];
     int ret;
 
     BUG_ON(!net);
     ret = __dev_alloc_name(net, name, buf);
     if (ret >= 0)
         strlcpy(dev->name, buf, IFNAMSIZ);
     return ret;
 }
 
 /**
  *  dev_alloc_name - allocate a name for a device
  *  @dev: device
  *  @name: name format string
  *
  *  Passed a format string - eg "lt%d" it will try and find a suitable
  *  id. It scans list of devices to build up a free map, then chooses
  *  the first empty slot. The caller must hold the dev_base or rtnl lock
  *  while allocating the name and adding the device in order to avoid
  *  duplicates.
  *  Limited to bits_per_byte * page size devices (ie 32K on most platforms).
  *  Returns the number of the unit assigned or a negative errno code.
  */
 
 int dev_alloc_name(struct net_device *dev, const char *name)
 {
     return dev_alloc_name_ns(dev_net(dev), dev, name);
 }
 EXPORT_SYMBOL(dev_alloc_name);
 
 static int dev_get_valid_name(struct net *net, struct net_device *dev,
                   const char *name)
 {
     BUG_ON(!net);
 
     if (!dev_valid_name(name))
         return -EINVAL;
 
     if (strchr(name, '%'))
         return dev_alloc_name_ns(net, dev, name);
     else if (netdev_name_in_use(net, name))
         return -EEXIST;
     else if (dev->name != name)
         strlcpy(dev->name, name, IFNAMSIZ);
 
     return 0;
 }
 
 /**
  *  dev_change_name - change name of a device
  *  @dev: device
  *  @newname: name (or format string) must be at least IFNAMSIZ
  *
  *  Change name of a device, can pass format strings "eth%d".
  *  for wildcarding.
  */
 int dev_change_name(struct net_device *dev, const char *newname)
 {
     unsigned char old_assign_type;
     char oldname[IFNAMSIZ];
     int err = 0;
     int ret;
     struct net *net;
 
     ASSERT_RTNL();
     BUG_ON(!dev_net(dev));
 
     net = dev_net(dev);
 
     /* Some auto-enslaved devices e.g. failover slaves are
      * special, as userspace might rename the device after
      * the interface had been brought up and running since
      * the point kernel initiated auto-enslavement. Allow
      * live name change even when these slave devices are
      * up and running.
      *
      * Typically, users of these auto-enslaving devices
      * don't actually care about slave name change, as
      * they are supposed to operate on master interface
      * directly.
      */
     if (dev->flags & IFF_UP &&
         likely(!(dev->priv_flags & IFF_LIVE_RENAME_OK)))
         return -EBUSY;
 
     down_write(&devnet_rename_sem);
 
     if (strncmp(newname, dev->name, IFNAMSIZ) == 0) {
         up_write(&devnet_rename_sem);
         return 0;
     }
 
     memcpy(oldname, dev->name, IFNAMSIZ);
 
     err = dev_get_valid_name(net, dev, newname);
     if (err < 0) {
         up_write(&devnet_rename_sem);
         return err;
     }
 
     if (oldname[0] && !strchr(oldname, '%'))
         netdev_info(dev, "renamed from %s\n", oldname);
 
     old_assign_type = dev->name_assign_type;
     dev->name_assign_type = NET_NAME_RENAMED;
 
 rollback:
     ret = device_rename(&dev->dev, dev->name);
     if (ret) {
         memcpy(dev->name, oldname, IFNAMSIZ);
         dev->name_assign_type = old_assign_type;
         up_write(&devnet_rename_sem);
         return ret;
     }
 
     up_write(&devnet_rename_sem);
 
     netdev_adjacent_rename_links(dev, oldname);
 
     write_lock(&dev_base_lock);
     netdev_name_node_del(dev->name_node);
     write_unlock(&dev_base_lock);
 
     synchronize_rcu();
 
     write_lock(&dev_base_lock);
     netdev_name_node_add(net, dev->name_node);
     write_unlock(&dev_base_lock);
 
     ret = call_netdevice_notifiers(NETDEV_CHANGENAME, dev);
     ret = notifier_to_errno(ret);
 
     if (ret) {
         /* err >= 0 after dev_alloc_name() or stores the first errno */
         if (err >= 0) {
             err = ret;
             down_write(&devnet_rename_sem);
             memcpy(dev->name, oldname, IFNAMSIZ);
             memcpy(oldname, newname, IFNAMSIZ);
             dev->name_assign_type = old_assign_type;
             old_assign_type = NET_NAME_RENAMED;
             goto rollback;
         } else {
             netdev_err(dev, "name change rollback failed: %d\n",
                    ret);
         }
     }
 
     return err;
 }
 
 /**
  *  dev_set_alias - change ifalias of a device
  *  @dev: device
  *  @alias: name up to IFALIASZ
  *  @len: limit of bytes to copy from info
  *
  *  Set ifalias for a device,
  */
 int dev_set_alias(struct net_device *dev, const char *alias, size_t len)
 {
     struct dev_ifalias *new_alias = NULL;
 
     if (len >= IFALIASZ)
         return -EINVAL;
 
     if (len) {
         new_alias = kmalloc(sizeof(*new_alias) + len + 1, GFP_KERNEL);
         if (!new_alias)
             return -ENOMEM;
 
         memcpy(new_alias->ifalias, alias, len);
         new_alias->ifalias[len] = 0;
     }
 
     mutex_lock(&ifalias_mutex);
     new_alias = rcu_replace_pointer(dev->ifalias, new_alias,
                     mutex_is_locked(&ifalias_mutex));
     mutex_unlock(&ifalias_mutex);
 
     if (new_alias)
         kfree_rcu(new_alias, rcuhead);
 
     return len;
 }
 EXPORT_SYMBOL(dev_set_alias);
 
 /**
  *  dev_get_alias - get ifalias of a device
  *  @dev: device
  *  @name: buffer to store name of ifalias
  *  @len: size of buffer
  *
  *  get ifalias for a device.  Caller must make sure dev cannot go
  *  away,  e.g. rcu read lock or own a reference count to device.
  */
 int dev_get_alias(const struct net_device *dev, char *name, size_t len)
 {
     const struct dev_ifalias *alias;
     int ret = 0;
 
     rcu_read_lock();
     alias = rcu_dereference(dev->ifalias);
     if (alias)
         ret = snprintf(name, len, "%s", alias->ifalias);
     rcu_read_unlock();
 
     return ret;
 }
 
 /**
  *  netdev_features_change - device changes features
  *  @dev: device to cause notification
  *
  *  Called to indicate a device has changed features.
  */
 void netdev_features_change(struct net_device *dev)
 {
     call_netdevice_notifiers(NETDEV_FEAT_CHANGE, dev);
 }
 EXPORT_SYMBOL(netdev_features_change);
 
 /**
  *  netdev_state_change - device changes state
  *  @dev: device to cause notification
  *
  *  Called to indicate a device has changed state. This function calls
  *  the notifier chains for netdev_chain and sends a NEWLINK message
  *  to the routing socket.
  */
 void netdev_state_change(struct net_device *dev)
 {
     if (dev->flags & IFF_UP) {
         struct netdev_notifier_change_info change_info = {
             .info.dev = dev,
         };
 
         call_netdevice_notifiers_info(NETDEV_CHANGE,
                           &change_info.info);
         rtmsg_ifinfo(RTM_NEWLINK, dev, 0, GFP_KERNEL);
     }
 }
 EXPORT_SYMBOL(netdev_state_change);
 
 /**
  * __netdev_notify_peers - notify network peers about existence of @dev,
  * to be called when rtnl lock is already held.
  * @dev: network device
  *
  * Generate traffic such that interested network peers are aware of
  * @dev, such as by generating a gratuitous ARP. This may be used when
  * a device wants to inform the rest of the network about some sort of
  * reconfiguration such as a failover event or virtual machine
  * migration.
  */
 void __netdev_notify_peers(struct net_device *dev)
 {
     ASSERT_RTNL();
     call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev);
     call_netdevice_notifiers(NETDEV_RESEND_IGMP, dev);
 }
 EXPORT_SYMBOL(__netdev_notify_peers);
 
 /**
  * netdev_notify_peers - notify network peers about existence of @dev
  * @dev: network device
  *
  * Generate traffic such that interested network peers are aware of
  * @dev, such as by generating a gratuitous ARP. This may be used when
  * a device wants to inform the rest of the network about some sort of
  * reconfiguration such as a failover event or virtual machine
  * migration.
  */
 void netdev_notify_peers(struct net_device *dev)
 {
     rtnl_lock();
     __netdev_notify_peers(dev);
     rtnl_unlock();
 }
 EXPORT_SYMBOL(netdev_notify_peers);
 
 static int napi_threaded_poll(void *data);
 
 static int napi_kthread_create(struct napi_struct *n)
 {
     int err = 0;
 
     /* Create and wake up the kthread once to put it in
      * TASK_INTERRUPTIBLE mode to avoid the blocked task
      * warning and work with loadavg.
      */
     n->thread = kthread_run(napi_threaded_poll, n, "napi/%s-%d",
                 n->dev->name, n->napi_id);
     if (IS_ERR(n->thread)) {
         err = PTR_ERR(n->thread);
         pr_err("kthread_run failed with err %d\n", err);
         n->thread = NULL;
     }
 
     return err;
 }
 
 static int __dev_open(struct net_device *dev, struct netlink_ext_ack *extack)
 {
     const struct net_device_ops *ops = dev->netdev_ops;
     int ret;
 
     ASSERT_RTNL();
     dev_addr_check(dev);
 
     if (!netif_device_present(dev)) {
         /* may be detached because parent is runtime-suspended */
         if (dev->dev.parent)
             pm_runtime_resume(dev->dev.parent);
         if (!netif_device_present(dev))
             return -ENODEV;
     }
 
     /* Block netpoll from trying to do any rx path servicing.
      * If we don't do this there is a chance ndo_poll_controller
      * or ndo_poll may be running while we open the device
      */
     netpoll_poll_disable(dev);
 
     ret = call_netdevice_notifiers_extack(NETDEV_PRE_UP, dev, extack);
     ret = notifier_to_errno(ret);
     if (ret)
         return ret;
 
     set_bit(__LINK_STATE_START, &dev->state);
 
     if (ops->ndo_validate_addr)
         ret = ops->ndo_validate_addr(dev);
 
     if (!ret && ops->ndo_open)
         ret = ops->ndo_open(dev);
 
     netpoll_poll_enable(dev);
 
     if (ret)
         clear_bit(__LINK_STATE_START, &dev->state);
     else {
         dev->flags |= IFF_UP;
         dev_set_rx_mode(dev);
         dev_activate(dev);
         add_device_randomness(dev->dev_addr, dev->addr_len);
     }
 
     return ret;
 }
 
 /**
  *  dev_open    - prepare an interface for use.
  *  @dev: device to open
  *  @extack: netlink extended ack
  *
  *  Takes a device from down to up state. The device's private open
  *  function is invoked and then the multicast lists are loaded. Finally
  *  the device is moved into the up state and a %NETDEV_UP message is
  *  sent to the netdev notifier chain.
  *
  *  Calling this function on an active interface is a nop. On a failure
  *  a negative errno code is returned.
  */
 int dev_open(struct net_device *dev, struct netlink_ext_ack *extack)
 {
     int ret;
 
     if (dev->flags & IFF_UP)
         return 0;
 
     ret = __dev_open(dev, extack);
     if (ret < 0)
         return ret;
 
     rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING, GFP_KERNEL);
     call_netdevice_notifiers(NETDEV_UP, dev);
 
     return ret;
 }
 EXPORT_SYMBOL(dev_open);
 
 static void __dev_close_many(struct list_head *head)
 {
     struct net_device *dev;
 
     ASSERT_RTNL();
     might_sleep();
 
     list_for_each_entry(dev, head, close_list) {
         /* Temporarily disable netpoll until the interface is down */
         netpoll_poll_disable(dev);
 
         call_netdevice_notifiers(NETDEV_GOING_DOWN, dev);
 
         clear_bit(__LINK_STATE_START, &dev->state);
 
         /* Synchronize to scheduled poll. We cannot touch poll list, it
          * can be even on different cpu. So just clear netif_running().
          *
          * dev->stop() will invoke napi_disable() on all of it's
          * napi_struct instances on this device.
          */
         smp_mb__after_atomic(); /* Commit netif_running(). */
     }
 
     dev_deactivate_many(head);
 
     list_for_each_entry(dev, head, close_list) {
         const struct net_device_ops *ops = dev->netdev_ops;
 
         /*
          *  Call the device specific close. This cannot fail.
          *  Only if device is UP
          *
          *  We allow it to be called even after a DETACH hot-plug
          *  event.
          */
         if (ops->ndo_stop)
             ops->ndo_stop(dev);
 
         dev->flags &= ~IFF_UP;
         netpoll_poll_enable(dev);
     }
 }
 
 static void __dev_close(struct net_device *dev)
 {
     LIST_HEAD(single);
 
     list_add(&dev->close_list, &single);
     __dev_close_many(&single);
     list_del(&single);
 }
 
 void dev_close_many(struct list_head *head, bool unlink)
 {
     struct net_device *dev, *tmp;
 
     /* Remove the devices that don't need to be closed */
     list_for_each_entry_safe(dev, tmp, head, close_list)
         if (!(dev->flags & IFF_UP))
             list_del_init(&dev->close_list);
 
     __dev_close_many(head);
 
     list_for_each_entry_safe(dev, tmp, head, close_list) {
         rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING, GFP_KERNEL);
         call_netdevice_notifiers(NETDEV_DOWN, dev);
         if (unlink)
             list_del_init(&dev->close_list);
     }
 }
 EXPORT_SYMBOL(dev_close_many);
 
 /**
  *  dev_close - shutdown an interface.
  *  @dev: device to shutdown
  *
  *  This function moves an active device into down state. A
  *  %NETDEV_GOING_DOWN is sent to the netdev notifier chain. The device
  *  is then deactivated and finally a %NETDEV_DOWN is sent to the notifier
  *  chain.
  */
 void dev_close(struct net_device *dev)
 {
     if (dev->flags & IFF_UP) {
         LIST_HEAD(single);
 
         list_add(&dev->close_list, &single);
         dev_close_many(&single, true);
         list_del(&single);
     }
 }
 EXPORT_SYMBOL(dev_close);
 
 
 /**
  *  dev_disable_lro - disable Large Receive Offload on a device
  *  @dev: device
  *
  *  Disable Large Receive Offload (LRO) on a net device.  Must be
  *  called under RTNL.  This is needed if received packets may be
  *  forwarded to another interface.
  */
 void dev_disable_lro(struct net_device *dev)
 {
     struct net_device *lower_dev;
     struct list_head *iter;
 
     dev->wanted_features &= ~NETIF_F_LRO;
     netdev_update_features(dev);
 
     if (unlikely(dev->features & NETIF_F_LRO))
         netdev_WARN(dev, "failed to disable LRO!\n");
 
     netdev_for_each_lower_dev(dev, lower_dev, iter)
         dev_disable_lro(lower_dev);
 }
 EXPORT_SYMBOL(dev_disable_lro);
 
 /**
  *  dev_disable_gro_hw - disable HW Generic Receive Offload on a device
  *  @dev: device
  *
  *  Disable HW Generic Receive Offload (GRO_HW) on a net device.  Must be
  *  called under RTNL.  This is needed if Generic XDP is installed on
  *  the device.
  */
 static void dev_disable_gro_hw(struct net_device *dev)
 {
     dev->wanted_features &= ~NETIF_F_GRO_HW;
     netdev_update_features(dev);
 
     if (unlikely(dev->features & NETIF_F_GRO_HW))
         netdev_WARN(dev, "failed to disable GRO_HW!\n");
 }
 
 const char *netdev_cmd_to_name(enum netdev_cmd cmd)
 {
 #define N(val)                      \
     case NETDEV_##val:              \
         return "NETDEV_" __stringify(val);
     switch (cmd) {
     N(UP) N(DOWN) N(REBOOT) N(CHANGE) N(REGISTER) N(UNREGISTER)
     N(CHANGEMTU) N(CHANGEADDR) N(GOING_DOWN) N(CHANGENAME) N(FEAT_CHANGE)
     N(BONDING_FAILOVER) N(PRE_UP) N(PRE_TYPE_CHANGE) N(POST_TYPE_CHANGE)
     N(POST_INIT) N(RELEASE) N(NOTIFY_PEERS) N(JOIN) N(CHANGEUPPER)
     N(RESEND_IGMP) N(PRECHANGEMTU) N(CHANGEINFODATA) N(BONDING_INFO)
     N(PRECHANGEUPPER) N(CHANGELOWERSTATE) N(UDP_TUNNEL_PUSH_INFO)
     N(UDP_TUNNEL_DROP_INFO) N(CHANGE_TX_QUEUE_LEN)
     N(CVLAN_FILTER_PUSH_INFO) N(CVLAN_FILTER_DROP_INFO)
     N(SVLAN_FILTER_PUSH_INFO) N(SVLAN_FILTER_DROP_INFO)
     N(PRE_CHANGEADDR) N(OFFLOAD_XSTATS_ENABLE) N(OFFLOAD_XSTATS_DISABLE)
     N(OFFLOAD_XSTATS_REPORT_USED) N(OFFLOAD_XSTATS_REPORT_DELTA)
     }
 #undef N
     return "UNKNOWN_NETDEV_EVENT";
 }
 EXPORT_SYMBOL_GPL(netdev_cmd_to_name);
 
 static int call_netdevice_notifier(struct notifier_block *nb, unsigned long val,
                    struct net_device *dev)
 {
     struct netdev_notifier_info info = {
         .dev = dev,
     };
 
     return nb->notifier_call(nb, val, &info);
 }
 
 static int call_netdevice_register_notifiers(struct notifier_block *nb,
                          struct net_device *dev)
 {
     int err;
 
     err = call_netdevice_notifier(nb, NETDEV_REGISTER, dev);
     err = notifier_to_errno(err);
     if (err)
         return err;
 
     if (!(dev->flags & IFF_UP))
         return 0;
 
     call_netdevice_notifier(nb, NETDEV_UP, dev);
     return 0;
 }
 
 static void call_netdevice_unregister_notifiers(struct notifier_block *nb,
                         struct net_device *dev)
 {
     if (dev->flags & IFF_UP) {
         call_netdevice_notifier(nb, NETDEV_GOING_DOWN,
                     dev);
         call_netdevice_notifier(nb, NETDEV_DOWN, dev);
     }
     call_netdevice_notifier(nb, NETDEV_UNREGISTER, dev);
 }
 
 static int call_netdevice_register_net_notifiers(struct notifier_block *nb,
                          struct net *net)
 {
     struct net_device *dev;
     int err;
 
     for_each_netdev(net, dev) {
         err = call_netdevice_register_notifiers(nb, dev);
         if (err)
             goto rollback;
     }
     return 0;
 
 rollback:
     for_each_netdev_continue_reverse(net, dev)
         call_netdevice_unregister_notifiers(nb, dev);
     return err;
 }
 
 static void call_netdevice_unregister_net_notifiers(struct notifier_block *nb,
                             struct net *net)
 {
     struct net_device *dev;
 
     for_each_netdev(net, dev)
         call_netdevice_unregister_notifiers(nb, dev);
 }
 
 static int dev_boot_phase = 1;
 
 /**
  * register_netdevice_notifier - register a network notifier block
  * @nb: notifier
  *
  * Register a notifier to be called when network device events occur.
  * The notifier passed is linked into the kernel structures and must
  * not be reused until it has been unregistered. A negative errno code
  * is returned on a failure.
  *
  * When registered all registration and up events are replayed
  * to the new notifier to allow device to have a race free
  * view of the network device list.
  */
 
 int register_netdevice_notifier(struct notifier_block *nb)
 {
     struct net *net;
     int err;
 
     /* Close race with setup_net() and cleanup_net() */
     down_write(&pernet_ops_rwsem);
     rtnl_lock();
     err = raw_notifier_chain_register(&netdev_chain, nb);
     if (err)
         goto unlock;
     if (dev_boot_phase)
         goto unlock;
     for_each_net(net) {
         err = call_netdevice_register_net_notifiers(nb, net);
         if (err)
             goto rollback;
     }
 
 unlock:
     rtnl_unlock();
     up_write(&pernet_ops_rwsem);
     return err;
 
 rollback:
     for_each_net_continue_reverse(net)
         call_netdevice_unregister_net_notifiers(nb, net);
 
     raw_notifier_chain_unregister(&netdev_chain, nb);
     goto unlock;
 }
 EXPORT_SYMBOL(register_netdevice_notifier);
 
 /**
  * unregister_netdevice_notifier - unregister a network notifier block
  * @nb: notifier
  *
  * Unregister a notifier previously registered by
  * register_netdevice_notifier(). The notifier is unlinked into the
  * kernel structures and may then be reused. A negative errno code
  * is returned on a failure.
  *
  * After unregistering unregister and down device events are synthesized
  * for all devices on the device list to the removed notifier to remove
  * the need for special case cleanup code.
  */
 
 int unregister_netdevice_notifier(struct notifier_block *nb)
 {
     struct net *net;
     int err;
 
     /* Close race with setup_net() and cleanup_net() */
     down_write(&pernet_ops_rwsem);
     rtnl_lock();
     err = raw_notifier_chain_unregister(&netdev_chain, nb);
     if (err)
         goto unlock;
 
     for_each_net(net)
         call_netdevice_unregister_net_notifiers(nb, net);
 
 unlock:
     rtnl_unlock();
     up_write(&pernet_ops_rwsem);
     return err;
 }
 EXPORT_SYMBOL(unregister_netdevice_notifier);
 
 static int __register_netdevice_notifier_net(struct net *net,
                          struct notifier_block *nb,
                          bool ignore_call_fail)
 {
     int err;
 
     err = raw_notifier_chain_register(&net->netdev_chain, nb);
     if (err)
         return err;
     if (dev_boot_phase)
         return 0;
 
     err = call_netdevice_register_net_notifiers(nb, net);
     if (err && !ignore_call_fail)
         goto chain_unregister;
 
     return 0;
 
 chain_unregister:
     raw_notifier_chain_unregister(&net->netdev_chain, nb);
     return err;
 }
 
 static int __unregister_netdevice_notifier_net(struct net *net,
                            struct notifier_block *nb)
 {
     int err;
 
     err = raw_notifier_chain_unregister(&net->netdev_chain, nb);
     if (err)
         return err;
 
     call_netdevice_unregister_net_notifiers(nb, net);
     return 0;
 }
 
 /**
  * register_netdevice_notifier_net - register a per-netns network notifier block
  * @net: network namespace
  * @nb: notifier
  *
  * Register a notifier to be called when network device events occur.
  * The notifier passed is linked into the kernel structures and must
  * not be reused until it has been unregistered. A negative errno code
  * is returned on a failure.
  *
  * When registered all registration and up events are replayed
  * to the new notifier to allow device to have a race free
  * view of the network device list.
  */
 
 int register_netdevice_notifier_net(struct net *net, struct notifier_block *nb)
 {
     int err;
 
     rtnl_lock();
     err = __register_netdevice_notifier_net(net, nb, false);
     rtnl_unlock();
     return err;
 }
 EXPORT_SYMBOL(register_netdevice_notifier_net);
 
 /**
  * unregister_netdevice_notifier_net - unregister a per-netns
  *                                     network notifier block
  * @net: network namespace
  * @nb: notifier
  *
  * Unregister a notifier previously registered by
  * register_netdevice_notifier(). The notifier is unlinked into the
  * kernel structures and may then be reused. A negative errno code
  * is returned on a failure.
  *
  * After unregistering unregister and down device events are synthesized
  * for all devices on the device list to the removed notifier to remove
  * the need for special case cleanup code.
  */
 
 int unregister_netdevice_notifier_net(struct net *net,
                       struct notifier_block *nb)
 {
     int err;
 
     rtnl_lock();
     err = __unregister_netdevice_notifier_net(net, nb);
     rtnl_unlock();
     return err;
 }
 EXPORT_SYMBOL(unregister_netdevice_notifier_net);
 
 int register_netdevice_notifier_dev_net(struct net_device *dev,
                     struct notifier_block *nb,
                     struct netdev_net_notifier *nn)
 {
     int err;
 
     rtnl_lock();
     err = __register_netdevice_notifier_net(dev_net(dev), nb, false);
     if (!err) {
         nn->nb = nb;
         list_add(&nn->list, &dev->net_notifier_list);
     }
     rtnl_unlock();
     return err;
 }
 EXPORT_SYMBOL(register_netdevice_notifier_dev_net);
 
 int unregister_netdevice_notifier_dev_net(struct net_device *dev,
                       struct notifier_block *nb,
                       struct netdev_net_notifier *nn)
 {
     int err;
 
     rtnl_lock();
     list_del(&nn->list);
     err = __unregister_netdevice_notifier_net(dev_net(dev), nb);
     rtnl_unlock();
     return err;
 }
 EXPORT_SYMBOL(unregister_netdevice_notifier_dev_net);
 
 static void move_netdevice_notifiers_dev_net(struct net_device *dev,
                          struct net *net)
 {
     struct netdev_net_notifier *nn;
 
     list_for_each_entry(nn, &dev->net_notifier_list, list) {
         __unregister_netdevice_notifier_net(dev_net(dev), nn->nb);
         __register_netdevice_notifier_net(net, nn->nb, true);
     }
 }
 
 /**
  *  call_netdevice_notifiers_info - call all network notifier blocks
  *  @val: value passed unmodified to notifier function
  *  @info: notifier information data
  *
  *  Call all network notifier blocks.  Parameters and return value
  *  are as for raw_notifier_call_chain().
  */
 
 static int call_netdevice_notifiers_info(unsigned long val,
                      struct netdev_notifier_info *info)
 {
     struct net *net = dev_net(info->dev);
     int ret;
 
     ASSERT_RTNL();
 
     /* Run per-netns notifier block chain first, then run the global one.
      * Hopefully, one day, the global one is going to be removed after
      * all notifier block registrators get converted to be per-netns.
      */
     ret = raw_notifier_call_chain(&net->netdev_chain, val, info);
     if (ret & NOTIFY_STOP_MASK)
         return ret;
     return raw_notifier_call_chain(&netdev_chain, val, info);
 }
 
 /**
  *  call_netdevice_notifiers_info_robust - call per-netns notifier blocks
  *                                         for and rollback on error
  *  @val_up: value passed unmodified to notifier function
  *  @val_down: value passed unmodified to the notifier function when
  *             recovering from an error on @val_up
  *  @info: notifier information data
  *
  *  Call all per-netns network notifier blocks, but not notifier blocks on
  *  the global notifier chain. Parameters and return value are as for
  *  raw_notifier_call_chain_robust().
  */
 
 static int
 call_netdevice_notifiers_info_robust(unsigned long val_up,
                      unsigned long val_down,
                      struct netdev_notifier_info *info)
 {
     struct net *net = dev_net(info->dev);
 
     ASSERT_RTNL();
 
     return raw_notifier_call_chain_robust(&net->netdev_chain,
                           val_up, val_down, info);
 }
 
 static int call_netdevice_notifiers_extack(unsigned long val,
                        struct net_device *dev,
                        struct netlink_ext_ack *extack)
 {
     struct netdev_notifier_info info = {
         .dev = dev,
         .extack = extack,
     };
 
     return call_netdevice_notifiers_info(val, &info);
 }
 
 /**
  *  call_netdevice_notifiers - call all network notifier blocks
  *      @val: value passed unmodified to notifier function
  *      @dev: net_device pointer passed unmodified to notifier function
  *
  *  Call all network notifier blocks.  Parameters and return value
  *  are as for raw_notifier_call_chain().
  */
 
 int call_netdevice_notifiers(unsigned long val, struct net_device *dev)
 {
     return call_netdevice_notifiers_extack(val, dev, NULL);
 }
 EXPORT_SYMBOL(call_netdevice_notifiers);
 
 /**
  *  call_netdevice_notifiers_mtu - call all network notifier blocks
  *  @val: value passed unmodified to notifier function
  *  @dev: net_device pointer passed unmodified to notifier function
  *  @arg: additional u32 argument passed to the notifier function
  *
  *  Call all network notifier blocks.  Parameters and return value
  *  are as for raw_notifier_call_chain().
  */
 static int call_netdevice_notifiers_mtu(unsigned long val,
                     struct net_device *dev, u32 arg)
 {
     struct netdev_notifier_info_ext info = {
         .info.dev = dev,
         .ext.mtu = arg,
     };
 
     BUILD_BUG_ON(offsetof(struct netdev_notifier_info_ext, info) != 0);
 
     return call_netdevice_notifiers_info(val, &info.info);
 }
 
 #ifdef CONFIG_NET_INGRESS
 static DEFINE_STATIC_KEY_FALSE(ingress_needed_key);
 
 void net_inc_ingress_queue(void)
 {
     static_branch_inc(&ingress_needed_key);
 }
 EXPORT_SYMBOL_GPL(net_inc_ingress_queue);
 
 void net_dec_ingress_queue(void)
 {
     static_branch_dec(&ingress_needed_key);
 }
 EXPORT_SYMBOL_GPL(net_dec_ingress_queue);
 #endif
 
 #ifdef CONFIG_NET_EGRESS
 static DEFINE_STATIC_KEY_FALSE(egress_needed_key);
 
 void net_inc_egress_queue(void)
 {
     static_branch_inc(&egress_needed_key);
 }
 EXPORT_SYMBOL_GPL(net_inc_egress_queue);
 
 void net_dec_egress_queue(void)
 {
     static_branch_dec(&egress_needed_key);
 }
 EXPORT_SYMBOL_GPL(net_dec_egress_queue);
 #endif
 
 DEFINE_STATIC_KEY_FALSE(netstamp_needed_key);
 EXPORT_SYMBOL(netstamp_needed_key);
 #ifdef CONFIG_JUMP_LABEL
 static atomic_t netstamp_needed_deferred;
 static atomic_t netstamp_wanted;
 static void netstamp_clear(struct work_struct *work)
 {
     int deferred = atomic_xchg(&netstamp_needed_deferred, 0);
     int wanted;
 
     wanted = atomic_add_return(deferred, &netstamp_wanted);
     if (wanted > 0)
         static_branch_enable(&netstamp_needed_key);
     else
         static_branch_disable(&netstamp_needed_key);
 }
 static DECLARE_WORK(netstamp_work, netstamp_clear);
 #endif
 
 void net_enable_timestamp(void)
 {
 #ifdef CONFIG_JUMP_LABEL
     int wanted;
 
     while (1) {
         wanted = atomic_read(&netstamp_wanted);
         if (wanted <= 0)
             break;
         if (atomic_cmpxchg(&netstamp_wanted, wanted, wanted + 1) == wanted)
             return;
     }
     atomic_inc(&netstamp_needed_deferred);
     schedule_work(&netstamp_work);
 #else
     static_branch_inc(&netstamp_needed_key);
 #endif
 }
 EXPORT_SYMBOL(net_enable_timestamp);
 
 void net_disable_timestamp(void)
 {
 #ifdef CONFIG_JUMP_LABEL
     int wanted;
 
     while (1) {
         wanted = atomic_read(&netstamp_wanted);
         if (wanted <= 1)
             break;
         if (atomic_cmpxchg(&netstamp_wanted, wanted, wanted - 1) == wanted)
             return;
     }
     atomic_dec(&netstamp_needed_deferred);
     schedule_work(&netstamp_work);
 #else
     static_branch_dec(&netstamp_needed_key);
 #endif
 }
 EXPORT_SYMBOL(net_disable_timestamp);
 
 static inline void net_timestamp_set(struct sk_buff *skb)
 {
     skb->tstamp = 0;
     skb->mono_delivery_time = 0;
     if (static_branch_unlikely(&netstamp_needed_key))
         skb->tstamp = ktime_get_real();
 }
 
 #define net_timestamp_check(COND, SKB)              \
     if (static_branch_unlikely(&netstamp_needed_key)) { \
         if ((COND) && !(SKB)->tstamp)           \
             (SKB)->tstamp = ktime_get_real();   \
     }                           \
 
 bool is_skb_forwardable(const struct net_device *dev, const struct sk_buff *skb)
 {
     return __is_skb_forwardable(dev, skb, true);
 }
 EXPORT_SYMBOL_GPL(is_skb_forwardable);
 
 static int __dev_forward_skb2(struct net_device *dev, struct sk_buff *skb,
                   bool check_mtu)
 {
     int ret = ____dev_forward_skb(dev, skb, check_mtu);
 
     if (likely(!ret)) {
         skb->protocol = eth_type_trans(skb, dev);
         skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);
     }
 
     return ret;
 }
 
 int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
 {
     return __dev_forward_skb2(dev, skb, true);
 }
 EXPORT_SYMBOL_GPL(__dev_forward_skb);
 
 /**
  * dev_forward_skb - loopback an skb to another netif
  *
  * @dev: destination network device
  * @skb: buffer to forward
  *
  * return values:
  *  NET_RX_SUCCESS  (no congestion)
  *  NET_RX_DROP     (packet was dropped, but freed)
  *
  * dev_forward_skb can be used for injecting an skb from the
  * start_xmit function of one device into the receive queue
  * of another device.
  *
  * The receiving device may be in another namespace, so
  * we have to clear all information in the skb that could
  * impact namespace isolation.
  */
 int dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
 {
     return __dev_forward_skb(dev, skb) ?: netif_rx_internal(skb);
 }
 EXPORT_SYMBOL_GPL(dev_forward_skb);
 
 int dev_forward_skb_nomtu(struct net_device *dev, struct sk_buff *skb)
 {
     return __dev_forward_skb2(dev, skb, false) ?: netif_rx_internal(skb);
 }
 
 static inline int deliver_skb(struct sk_buff *skb,
                   struct packet_type *pt_prev,
                   struct net_device *orig_dev)
 {
     if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC)))
         return -ENOMEM;
     refcount_inc(&skb->users);
     return pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
 }
 
 static inline void deliver_ptype_list_skb(struct sk_buff *skb,
                       struct packet_type **pt,
                       struct net_device *orig_dev,
                       __be16 type,
                       struct list_head *ptype_list)
 {
     struct packet_type *ptype, *pt_prev = *pt;
 
     list_for_each_entry_rcu(ptype, ptype_list, list) {
         if (ptype->type != type)
             continue;
         if (pt_prev)
             deliver_skb(skb, pt_prev, orig_dev);
         pt_prev = ptype;
     }
     *pt = pt_prev;
 }
 
 static inline bool skb_loop_sk(struct packet_type *ptype, struct sk_buff *skb)
 {
     if (!ptype->af_packet_priv || !skb->sk)
         return false;
 
     if (ptype->id_match)
         return ptype->id_match(ptype, skb->sk);
     else if ((struct sock *)ptype->af_packet_priv == skb->sk)
         return true;
 
     return false;
 }
 
 /**
  * dev_nit_active - return true if any network interface taps are in use
  *
  * @dev: network device to check for the presence of taps
  */
 bool dev_nit_active(struct net_device *dev)
 {
     return !list_empty(&ptype_all) || !list_empty(&dev->ptype_all);
 }
 EXPORT_SYMBOL_GPL(dev_nit_active);
 
 /*
  *  Support routine. Sends outgoing frames to any network
  *  taps currently in use.
  */
 
 void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
 {
     struct packet_type *ptype;
     struct sk_buff *skb2 = NULL;
     struct packet_type *pt_prev = NULL;
     struct list_head *ptype_list = &ptype_all;
 
     rcu_read_lock();
 again:
     list_for_each_entry_rcu(ptype, ptype_list, list) {
         if (ptype->ignore_outgoing)
             continue;
 
         /* Never send packets back to the socket
          * they originated from - MvS (miquels@drinkel.ow.org)
          */
         if (skb_loop_sk(ptype, skb))
             continue;
 
         if (pt_prev) {
             deliver_skb(skb2, pt_prev, skb->dev);
             pt_prev = ptype;
             continue;
         }
 
         /* need to clone skb, done only once */
         skb2 = skb_clone(skb, GFP_ATOMIC);
         if (!skb2)
             goto out_unlock;
 
         net_timestamp_set(skb2);
 
         /* skb->nh should be correctly
          * set by sender, so that the second statement is
          * just protection against buggy protocols.
          */
         skb_reset_mac_header(skb2);
 
         if (skb_network_header(skb2) < skb2->data ||
             skb_network_header(skb2) > skb_tail_pointer(skb2)) {
             net_crit_ratelimited("protocol %04x is buggy, dev %s\n",
                          ntohs(skb2->protocol),
                          dev->name);
             skb_reset_network_header(skb2);
         }
 
         skb2->transport_header = skb2->network_header;
         skb2->pkt_type = PACKET_OUTGOING;
         pt_prev = ptype;
     }
 
     if (ptype_list == &ptype_all) {
         ptype_list = &dev->ptype_all;
         goto again;
     }
 out_unlock:
     if (pt_prev) {
         if (!skb_orphan_frags_rx(skb2, GFP_ATOMIC))
             pt_prev->func(skb2, skb->dev, pt_prev, skb->dev);
         else
             kfree_skb(skb2);
     }
     rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(dev_queue_xmit_nit);
 
 /**
  * netif_setup_tc - Handle tc mappings on real_num_tx_queues change
  * @dev: Network device
  * @txq: number of queues available
  *
  * If real_num_tx_queues is changed the tc mappings may no longer be
  * valid. To resolve this verify the tc mapping remains valid and if
  * not NULL the mapping. With no priorities mapping to this
  * offset/count pair it will no longer be used. In the worst case TC0
  * is invalid nothing can be done so disable priority mappings. If is
  * expected that drivers will fix this mapping if they can before
  * calling netif_set_real_num_tx_queues.
  */
 static void netif_setup_tc(struct net_device *dev, unsigned int txq)
 {
     int i;
     struct netdev_tc_txq *tc = &dev->tc_to_txq[0];
 
     /* If TC0 is invalidated disable TC mapping */
     if (tc->offset + tc->count > txq) {
         netdev_warn(dev, "Number of in use tx queues changed invalidating tc mappings. Priority traffic classification disabled!\n");
         dev->num_tc = 0;
         return;
     }
 
     /* Invalidated prio to tc mappings set to TC0 */
     for (i = 1; i < TC_BITMASK + 1; i++) {
         int q = netdev_get_prio_tc_map(dev, i);
 
         tc = &dev->tc_to_txq[q];
         if (tc->offset + tc->count > txq) {
             netdev_warn(dev, "Number of in use tx queues changed. Priority %i to tc mapping %i is no longer valid. Setting map to 0\n",
                     i, q);
             netdev_set_prio_tc_map(dev, i, 0);
         }
     }
 }
 
 int netdev_txq_to_tc(struct net_device *dev, unsigned int txq)
 {
     if (dev->num_tc) {
         struct netdev_tc_txq *tc = &dev->tc_to_txq[0];
         int i;
 
         /* walk through the TCs and see if it falls into any of them */
         for (i = 0; i < TC_MAX_QUEUE; i++, tc++) {
             if ((txq - tc->offset) < tc->count)
                 return i;
         }
 
         /* didn't find it, just return -1 to indicate no match */
         return -1;
     }
 
     return 0;
 }
 EXPORT_SYMBOL(netdev_txq_to_tc);
 
 #ifdef CONFIG_XPS
 static struct static_key xps_needed __read_mostly;
 static struct static_key xps_rxqs_needed __read_mostly;
 static DEFINE_MUTEX(xps_map_mutex);
 #define xmap_dereference(P)     \
     rcu_dereference_protected((P), lockdep_is_held(&xps_map_mutex))
 
 static bool remove_xps_queue(struct xps_dev_maps *dev_maps,
                  struct xps_dev_maps *old_maps, int tci, u16 index)
 {
     struct xps_map *map = NULL;
     int pos;
 
     if (dev_maps)
         map = xmap_dereference(dev_maps->attr_map[tci]);
     if (!map)
         return false;
 
     for (pos = map->len; pos--;) {
         if (map->queues[pos] != index)
             continue;
 
         if (map->len > 1) {
             map->queues[pos] = map->queues[--map->len];
             break;
         }
 
         if (old_maps)
             RCU_INIT_POINTER(old_maps->attr_map[tci], NULL);
         RCU_INIT_POINTER(dev_maps->attr_map[tci], NULL);
         kfree_rcu(map, rcu);
         return false;
     }
 
     return true;
 }
 
 static bool remove_xps_queue_cpu(struct net_device *dev,
                  struct xps_dev_maps *dev_maps,
                  int cpu, u16 offset, u16 count)
 {
     int num_tc = dev_maps->num_tc;
     bool active = false;
     int tci;
 
     for (tci = cpu * num_tc; num_tc--; tci++) {
         int i, j;
 
         for (i = count, j = offset; i--; j++) {
             if (!remove_xps_queue(dev_maps, NULL, tci, j))
                 break;
         }
 
         active |= i < 0;
     }
 
     return active;
 }
 
 static void reset_xps_maps(struct net_device *dev,
                struct xps_dev_maps *dev_maps,
                enum xps_map_type type)
 {
     static_key_slow_dec_cpuslocked(&xps_needed);
     if (type == XPS_RXQS)
         static_key_slow_dec_cpuslocked(&xps_rxqs_needed);
 
     RCU_INIT_POINTER(dev->xps_maps[type], NULL);
 
     kfree_rcu(dev_maps, rcu);
 }
 
 static void clean_xps_maps(struct net_device *dev, enum xps_map_type type,
                u16 offset, u16 count)
 {
     struct xps_dev_maps *dev_maps;
     bool active = false;
     int i, j;
 
     dev_maps = xmap_dereference(dev->xps_maps[type]);
     if (!dev_maps)
         return;
 
     for (j = 0; j < dev_maps->nr_ids; j++)
         active |= remove_xps_queue_cpu(dev, dev_maps, j, offset, count);
     if (!active)
         reset_xps_maps(dev, dev_maps, type);
 
     if (type == XPS_CPUS) {
         for (i = offset + (count - 1); count--; i--)
             netdev_queue_numa_node_write(
                 netdev_get_tx_queue(dev, i), NUMA_NO_NODE);
     }
 }
 
 static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
                    u16 count)
 {
     if (!static_key_false(&xps_needed))
         return;
 
     cpus_read_lock();
     mutex_lock(&xps_map_mutex);
 
     if (static_key_false(&xps_rxqs_needed))
         clean_xps_maps(dev, XPS_RXQS, offset, count);
 
     clean_xps_maps(dev, XPS_CPUS, offset, count);
 
     mutex_unlock(&xps_map_mutex);
     cpus_read_unlock();
 }
 
 static void netif_reset_xps_queues_gt(struct net_device *dev, u16 index)
 {
     netif_reset_xps_queues(dev, index, dev->num_tx_queues - index);
 }
 
 static struct xps_map *expand_xps_map(struct xps_map *map, int attr_index,
                       u16 index, bool is_rxqs_map)
 {
     struct xps_map *new_map;
     int alloc_len = XPS_MIN_MAP_ALLOC;
     int i, pos;
 
     for (pos = 0; map && pos < map->len; pos++) {
         if (map->queues[pos] != index)
             continue;
         return map;
     }
 
     /* Need to add tx-queue to this CPU's/rx-queue's existing map */
     if (map) {
         if (pos < map->alloc_len)
             return map;
 
         alloc_len = map->alloc_len * 2;
     }
 
     /* Need to allocate new map to store tx-queue on this CPU's/rx-queue's
      *  map
      */
     if (is_rxqs_map)
         new_map = kzalloc(XPS_MAP_SIZE(alloc_len), GFP_KERNEL);
     else
         new_map = kzalloc_node(XPS_MAP_SIZE(alloc_len), GFP_KERNEL,
                        cpu_to_node(attr_index));
     if (!new_map)
         return NULL;
 
     for (i = 0; i < pos; i++)
         new_map->queues[i] = map->queues[i];
     new_map->alloc_len = alloc_len;
     new_map->len = pos;
 
     return new_map;
 }
 
 /* Copy xps maps at a given index */
 static void xps_copy_dev_maps(struct xps_dev_maps *dev_maps,
                   struct xps_dev_maps *new_dev_maps, int index,
                   int tc, bool skip_tc)
 {
     int i, tci = index * dev_maps->num_tc;
     struct xps_map *map;
 
     /* copy maps belonging to foreign traffic classes */
     for (i = 0; i < dev_maps->num_tc; i++, tci++) {
         if (i == tc && skip_tc)
             continue;
 
         /* fill in the new device map from the old device map */
         map = xmap_dereference(dev_maps->attr_map[tci]);
         RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
     }
 }
 
 /* Must be called under cpus_read_lock */
 int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
               u16 index, enum xps_map_type type)
 {
     struct xps_dev_maps *dev_maps, *new_dev_maps = NULL, *old_dev_maps = NULL;
     const unsigned long *online_mask = NULL;
     bool active = false, copy = false;
     int i, j, tci, numa_node_id = -2;
     int maps_sz, num_tc = 1, tc = 0;
     struct xps_map *map, *new_map;
     unsigned int nr_ids;
 
     if (dev->num_tc) {
         /* Do not allow XPS on subordinate device directly */
         num_tc = dev->num_tc;
         if (num_tc < 0)
             return -EINVAL;
 
         /* If queue belongs to subordinate dev use its map */
         dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
 
         tc = netdev_txq_to_tc(dev, index);
         if (tc < 0)
             return -EINVAL;
     }
 
     mutex_lock(&xps_map_mutex);
 
     dev_maps = xmap_dereference(dev->xps_maps[type]);
     if (type == XPS_RXQS) {
         maps_sz = XPS_RXQ_DEV_MAPS_SIZE(num_tc, dev->num_rx_queues);
         nr_ids = dev->num_rx_queues;
     } else {
         maps_sz = XPS_CPU_DEV_MAPS_SIZE(num_tc);
         if (num_possible_cpus() > 1)
             online_mask = cpumask_bits(cpu_online_mask);
         nr_ids = nr_cpu_ids;
     }
 
     if (maps_sz < L1_CACHE_BYTES)
         maps_sz = L1_CACHE_BYTES;
 
     /* The old dev_maps could be larger or smaller than the one we're
      * setting up now, as dev->num_tc or nr_ids could have been updated in
      * between. We could try to be smart, but let's be safe instead and only
      * copy foreign traffic classes if the two map sizes match.
      */
     if (dev_maps &&
         dev_maps->num_tc == num_tc && dev_maps->nr_ids == nr_ids)
         copy = true;
 
     /* allocate memory for queue storage */
     for (j = -1; j = netif_attrmask_next_and(j, online_mask, mask, nr_ids),
          j < nr_ids;) {
         if (!new_dev_maps) {
             new_dev_maps = kzalloc(maps_sz, GFP_KERNEL);
             if (!new_dev_maps) {
                 mutex_unlock(&xps_map_mutex);
                 return -ENOMEM;
             }
 
             new_dev_maps->nr_ids = nr_ids;
             new_dev_maps->num_tc = num_tc;
         }
 
         tci = j * num_tc + tc;
         map = copy ? xmap_dereference(dev_maps->attr_map[tci]) : NULL;
 
         map = expand_xps_map(map, j, index, type == XPS_RXQS);
         if (!map)
             goto error;
 
         RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
     }
 
     if (!new_dev_maps)
         goto out_no_new_maps;
 
     if (!dev_maps) {
         /* Increment static keys at most once per type */
         static_key_slow_inc_cpuslocked(&xps_needed);
         if (type == XPS_RXQS)
             static_key_slow_inc_cpuslocked(&xps_rxqs_needed);
     }
 
     for (j = 0; j < nr_ids; j++) {
         bool skip_tc = false;
 
         tci = j * num_tc + tc;
         if (netif_attr_test_mask(j, mask, nr_ids) &&
             netif_attr_test_online(j, online_mask, nr_ids)) {
             /* add tx-queue to CPU/rx-queue maps */
             int pos = 0;
 
             skip_tc = true;
 
             map = xmap_dereference(new_dev_maps->attr_map[tci]);
             while ((pos < map->len) && (map->queues[pos] != index))
                 pos++;
 
             if (pos == map->len)
                 map->queues[map->len++] = index;
 #ifdef CONFIG_NUMA
             if (type == XPS_CPUS) {
                 if (numa_node_id == -2)
                     numa_node_id = cpu_to_node(j);
                 else if (numa_node_id != cpu_to_node(j))
                     numa_node_id = -1;
             }
 #endif
         }
 
         if (copy)
             xps_copy_dev_maps(dev_maps, new_dev_maps, j, tc,
                       skip_tc);
     }
 
     rcu_assign_pointer(dev->xps_maps[type], new_dev_maps);
 
     /* Cleanup old maps */
     if (!dev_maps)
         goto out_no_old_maps;
 
     for (j = 0; j < dev_maps->nr_ids; j++) {
         for (i = num_tc, tci = j * dev_maps->num_tc; i--; tci++) {
             map = xmap_dereference(dev_maps->attr_map[tci]);
             if (!map)
                 continue;
 
             if (copy) {
                 new_map = xmap_dereference(new_dev_maps->attr_map[tci]);
                 if (map == new_map)
                     continue;
             }
 
             RCU_INIT_POINTER(dev_maps->attr_map[tci], NULL);
             kfree_rcu(map, rcu);
         }
     }
 
     old_dev_maps = dev_maps;
 
 out_no_old_maps:
     dev_maps = new_dev_maps;
     active = true;
 
 out_no_new_maps:
     if (type == XPS_CPUS)
         /* update Tx queue numa node */
         netdev_queue_numa_node_write(netdev_get_tx_queue(dev, index),
                          (numa_node_id >= 0) ?
                          numa_node_id : NUMA_NO_NODE);
 
     if (!dev_maps)
         goto out_no_maps;
 
     /* removes tx-queue from unused CPUs/rx-queues */
     for (j = 0; j < dev_maps->nr_ids; j++) {
         tci = j * dev_maps->num_tc;
 
         for (i = 0; i < dev_maps->num_tc; i++, tci++) {
             if (i == tc &&
                 netif_attr_test_mask(j, mask, dev_maps->nr_ids) &&
                 netif_attr_test_online(j, online_mask, dev_maps->nr_ids))
                 continue;
 
             active |= remove_xps_queue(dev_maps,
                            copy ? old_dev_maps : NULL,
                            tci, index);
         }
     }
 
     if (old_dev_maps)
         kfree_rcu(old_dev_maps, rcu);
 
     /* free map if not active */
     if (!active)
         reset_xps_maps(dev, dev_maps, type);
 
 out_no_maps:
     mutex_unlock(&xps_map_mutex);
 
     return 0;
 error:
     /* remove any maps that we added */
     for (j = 0; j < nr_ids; j++) {
         for (i = num_tc, tci = j * num_tc; i--; tci++) {
             new_map = xmap_dereference(new_dev_maps->attr_map[tci]);
             map = copy ?
                   xmap_dereference(dev_maps->attr_map[tci]) :
                   NULL;
             if (new_map && new_map != map)
                 kfree(new_map);
         }
     }
 
     mutex_unlock(&xps_map_mutex);
 
     kfree(new_dev_maps);
     return -ENOMEM;
 }
 EXPORT_SYMBOL_GPL(__netif_set_xps_queue);
 
 int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,
             u16 index)
 {
     int ret;
 
     cpus_read_lock();
     ret =  __netif_set_xps_queue(dev, cpumask_bits(mask), index, XPS_CPUS);
     cpus_read_unlock();
 
     return ret;
 }
 EXPORT_SYMBOL(netif_set_xps_queue);
 
 #endif
 static void netdev_unbind_all_sb_channels(struct net_device *dev)
 {
     struct netdev_queue *txq = &dev->_tx[dev->num_tx_queues];
 
     /* Unbind any subordinate channels */
     while (txq-- != &dev->_tx[0]) {
         if (txq->sb_dev)
             netdev_unbind_sb_channel(dev, txq->sb_dev);
     }
 }
 
 void netdev_reset_tc(struct net_device *dev)
 {
 #ifdef CONFIG_XPS
     netif_reset_xps_queues_gt(dev, 0);
 #endif
     netdev_unbind_all_sb_channels(dev);
 
     /* Reset TC configuration of device */
     dev->num_tc = 0;
     memset(dev->tc_to_txq, 0, sizeof(dev->tc_to_txq));
     memset(dev->prio_tc_map, 0, sizeof(dev->prio_tc_map));
 }
 EXPORT_SYMBOL(netdev_reset_tc);
 
 int netdev_set_tc_queue(struct net_device *dev, u8 tc, u16 count, u16 offset)
 {
     if (tc >= dev->num_tc)
         return -EINVAL;
 
 #ifdef CONFIG_XPS
     netif_reset_xps_queues(dev, offset, count);
 #endif
     dev->tc_to_txq[tc].count = count;
     dev->tc_to_txq[tc].offset = offset;
     return 0;
 }
 EXPORT_SYMBOL(netdev_set_tc_queue);
 
 int netdev_set_num_tc(struct net_device *dev, u8 num_tc)
 {
     if (num_tc > TC_MAX_QUEUE)
         return -EINVAL;
 
 #ifdef CONFIG_XPS
     netif_reset_xps_queues_gt(dev, 0);
 #endif
     netdev_unbind_all_sb_channels(dev);
 
     dev->num_tc = num_tc;
     return 0;
 }
 EXPORT_SYMBOL(netdev_set_num_tc);
 
 void netdev_unbind_sb_channel(struct net_device *dev,
                   struct net_device *sb_dev)
 {
     struct netdev_queue *txq = &dev->_tx[dev->num_tx_queues];
 
 #ifdef CONFIG_XPS
     netif_reset_xps_queues_gt(sb_dev, 0);
 #endif
     memset(sb_dev->tc_to_txq, 0, sizeof(sb_dev->tc_to_txq));
     memset(sb_dev->prio_tc_map, 0, sizeof(sb_dev->prio_tc_map));
 
     while (txq-- != &dev->_tx[0]) {
         if (txq->sb_dev == sb_dev)
             txq->sb_dev = NULL;
     }
 }
 EXPORT_SYMBOL(netdev_unbind_sb_channel);
 
 int netdev_bind_sb_channel_queue(struct net_device *dev,
                  struct net_device *sb_dev,
                  u8 tc, u16 count, u16 offset)
 {
     /* Make certain the sb_dev and dev are already configured */
     if (sb_dev->num_tc >= 0 || tc >= dev->num_tc)
         return -EINVAL;
 
     /* We cannot hand out queues we don't have */
     if ((offset + count) > dev->real_num_tx_queues)
         return -EINVAL;
 
     /* Record the mapping */
     sb_dev->tc_to_txq[tc].count = count;
     sb_dev->tc_to_txq[tc].offset = offset;
 
     /* Provide a way for Tx queue to find the tc_to_txq map or
      * XPS map for itself.
      */
     while (count--)
         netdev_get_tx_queue(dev, count + offset)->sb_dev = sb_dev;
 
     return 0;
 }
 EXPORT_SYMBOL(netdev_bind_sb_channel_queue);
 
 int netdev_set_sb_channel(struct net_device *dev, u16 channel)
 {
     /* Do not use a multiqueue device to represent a subordinate channel */
     if (netif_is_multiqueue(dev))
         return -ENODEV;
 
     /* We allow channels 1 - 32767 to be used for subordinate channels.
      * Channel 0 is meant to be "native" mode and used only to represent
      * the main root device. We allow writing 0 to reset the device back
      * to normal mode after being used as a subordinate channel.
      */
     if (channel > S16_MAX)
         return -EINVAL;
 
     dev->num_tc = -channel;
 
     return 0;
 }
 EXPORT_SYMBOL(netdev_set_sb_channel);
 
 /*
  * Routine to help set real_num_tx_queues. To avoid skbs mapped to queues
  * greater than real_num_tx_queues stale skbs on the qdisc must be flushed.
  */
 int netif_set_real_num_tx_queues(struct net_device *dev, unsigned int txq)
 {
     bool disabling;
     int rc;
 
     disabling = txq < dev->real_num_tx_queues;
 
     if (txq < 1 || txq > dev->num_tx_queues)
         return -EINVAL;
 
     if (dev->reg_state == NETREG_REGISTERED ||
         dev->reg_state == NETREG_UNREGISTERING) {
         ASSERT_RTNL();
 
         rc = netdev_queue_update_kobjects(dev, dev->real_num_tx_queues,
                           txq);
         if (rc)
             return rc;
 
         if (dev->num_tc)
             netif_setup_tc(dev, txq);
 
         dev_qdisc_change_real_num_tx(dev, txq);
 
         dev->real_num_tx_queues = txq;
 
         if (disabling) {
             synchronize_net();
             qdisc_reset_all_tx_gt(dev, txq);
 #ifdef CONFIG_XPS
             netif_reset_xps_queues_gt(dev, txq);
 #endif
         }
     } else {
         dev->real_num_tx_queues = txq;
     }
 
     return 0;
 }
 EXPORT_SYMBOL(netif_set_real_num_tx_queues);
 
 #ifdef CONFIG_SYSFS
 /**
  *  netif_set_real_num_rx_queues - set actual number of RX queues used
  *  @dev: Network device
  *  @rxq: Actual number of RX queues
  *
  *  This must be called either with the rtnl_lock held or before
  *  registration of the net device.  Returns 0 on success, or a
  *  negative error code.  If called before registration, it always
  *  succeeds.
  */
 int netif_set_real_num_rx_queues(struct net_device *dev, unsigned int rxq)
 {
     int rc;
 
     if (rxq < 1 || rxq > dev->num_rx_queues)
         return -EINVAL;
 
     if (dev->reg_state == NETREG_REGISTERED) {
         ASSERT_RTNL();
 
         rc = net_rx_queue_update_kobjects(dev, dev->real_num_rx_queues,
                           rxq);
         if (rc)
             return rc;
     }
 
     dev->real_num_rx_queues = rxq;
     return 0;
 }
 EXPORT_SYMBOL(netif_set_real_num_rx_queues);
 #endif
 
 /**
  *  netif_set_real_num_queues - set actual number of RX and TX queues used
  *  @dev: Network device
  *  @txq: Actual number of TX queues
  *  @rxq: Actual number of RX queues
  *
  *  Set the real number of both TX and RX queues.
  *  Does nothing if the number of queues is already correct.
  */
 int netif_set_real_num_queues(struct net_device *dev,
                   unsigned int txq, unsigned int rxq)
 {
     unsigned int old_rxq = dev->real_num_rx_queues;
     int err;
 
     if (txq < 1 || txq > dev->num_tx_queues ||
         rxq < 1 || rxq > dev->num_rx_queues)
         return -EINVAL;
 
     /* Start from increases, so the error path only does decreases -
      * decreases can't fail.
      */
     if (rxq > dev->real_num_rx_queues) {
         err = netif_set_real_num_rx_queues(dev, rxq);
         if (err)
             return err;
     }
     if (txq > dev->real_num_tx_queues) {
         err = netif_set_real_num_tx_queues(dev, txq);
         if (err)
             goto undo_rx;
     }
     if (rxq < dev->real_num_rx_queues)
         WARN_ON(netif_set_real_num_rx_queues(dev, rxq));
     if (txq < dev->real_num_tx_queues)
         WARN_ON(netif_set_real_num_tx_queues(dev, txq));
 
     return 0;
 undo_rx:
     WARN_ON(netif_set_real_num_rx_queues(dev, old_rxq));
     return err;
 }
 EXPORT_SYMBOL(netif_set_real_num_queues);
 
 /**
  * netif_set_tso_max_size() - set the max size of TSO frames supported
  * @dev:    netdev to update
  * @size:   max skb->len of a TSO frame
  *
  * Set the limit on the size of TSO super-frames the device can handle.
  * Unless explicitly set the stack will assume the value of
  * %GSO_LEGACY_MAX_SIZE.
  */
 void netif_set_tso_max_size(struct net_device *dev, unsigned int size)
 {
     dev->tso_max_size = min(GSO_MAX_SIZE, size);
     if (size < READ_ONCE(dev->gso_max_size))
         netif_set_gso_max_size(dev, size);
 }
 EXPORT_SYMBOL(netif_set_tso_max_size);
 
 /**
  * netif_set_tso_max_segs() - set the max number of segs supported for TSO
  * @dev:    netdev to update
  * @segs:   max number of TCP segments
  *
  * Set the limit on the number of TCP segments the device can generate from
  * a single TSO super-frame.
  * Unless explicitly set the stack will assume the value of %GSO_MAX_SEGS.
  */
 void netif_set_tso_max_segs(struct net_device *dev, unsigned int segs)
 {
     dev->tso_max_segs = segs;
     if (segs < READ_ONCE(dev->gso_max_segs))
         netif_set_gso_max_segs(dev, segs);
 }
 EXPORT_SYMBOL(netif_set_tso_max_segs);
 
 /**
  * netif_inherit_tso_max() - copy all TSO limits from a lower device to an upper
  * @to:     netdev to update
  * @from:   netdev from which to copy the limits
  */
 void netif_inherit_tso_max(struct net_device *to, const struct net_device *from)
 {
     netif_set_tso_max_size(to, from->tso_max_size);
     netif_set_tso_max_segs(to, from->tso_max_segs);
 }
 EXPORT_SYMBOL(netif_inherit_tso_max);
 
 /**
  * netif_get_num_default_rss_queues - default number of RSS queues
  *
  * Default value is the number of physical cores if there are only 1 or 2, or
  * divided by 2 if there are more.
  */
 int netif_get_num_default_rss_queues(void)
 {
     cpumask_var_t cpus;
     int cpu, count = 0;
 
     if (unlikely(is_kdump_kernel() || !zalloc_cpumask_var(&cpus, GFP_KERNEL)))
         return 1;
 
     cpumask_copy(cpus, cpu_online_mask);
     for_each_cpu(cpu, cpus) {
         ++count;
         cpumask_andnot(cpus, cpus, topology_sibling_cpumask(cpu));
     }
     free_cpumask_var(cpus);
 
     return count > 2 ? DIV_ROUND_UP(count, 2) : count;
 }
 EXPORT_SYMBOL(netif_get_num_default_rss_queues);
 
 static void __netif_reschedule(struct Qdisc *q)
 {
     struct softnet_data *sd;
     unsigned long flags;
 
     local_irq_save(flags);
     sd = this_cpu_ptr(&softnet_data);
     q->next_sched = NULL;
     *sd->output_queue_tailp = q;
     sd->output_queue_tailp = &q->next_sched;
     raise_softirq_irqoff(NET_TX_SOFTIRQ);
     local_irq_restore(flags);
 }
 
 void __netif_schedule(struct Qdisc *q)
 {
     if (!test_and_set_bit(__QDISC_STATE_SCHED, &q->state))
         __netif_reschedule(q);
 }
 EXPORT_SYMBOL(__netif_schedule);
 
 struct dev_kfree_skb_cb {
     enum skb_free_reason reason;
 };
 
 static struct dev_kfree_skb_cb *get_kfree_skb_cb(const struct sk_buff *skb)
 {
     return (struct dev_kfree_skb_cb *)skb->cb;
 }
 
 void netif_schedule_queue(struct netdev_queue *txq)
 {
     rcu_read_lock();
     if (!netif_xmit_stopped(txq)) {
         struct Qdisc *q = rcu_dereference(txq->qdisc);
 
         __netif_schedule(q);
     }
     rcu_read_unlock();
 }
 EXPORT_SYMBOL(netif_schedule_queue);
 
 void netif_tx_wake_queue(struct netdev_queue *dev_queue)
 {
     if (test_and_clear_bit(__QUEUE_STATE_DRV_XOFF, &dev_queue->state)) {
         struct Qdisc *q;
 
         rcu_read_lock();
         q = rcu_dereference(dev_queue->qdisc);
         __netif_schedule(q);
         rcu_read_unlock();
     }
 }
 EXPORT_SYMBOL(netif_tx_wake_queue);
 
 void __dev_kfree_skb_irq(struct sk_buff *skb, enum skb_free_reason reason)
 {
     unsigned long flags;
 
     if (unlikely(!skb))
         return;
 
     if (likely(refcount_read(&skb->users) == 1)) {
         smp_rmb();
         refcount_set(&skb->users, 0);
     } else if (likely(!refcount_dec_and_test(&skb->users))) {
         return;
     }
     get_kfree_skb_cb(skb)->reason = reason;
     local_irq_save(flags);
     skb->next = __this_cpu_read(softnet_data.completion_queue);
     __this_cpu_write(softnet_data.completion_queue, skb);
     raise_softirq_irqoff(NET_TX_SOFTIRQ);
     local_irq_restore(flags);
 }
 EXPORT_SYMBOL(__dev_kfree_skb_irq);
 
 void __dev_kfree_skb_any(struct sk_buff *skb, enum skb_free_reason reason)
 {
     if (in_hardirq() || irqs_disabled())
         __dev_kfree_skb_irq(skb, reason);
     else
         dev_kfree_skb(skb);
 }
 EXPORT_SYMBOL(__dev_kfree_skb_any);
 
 
 /**
  * netif_device_detach - mark device as removed
  * @dev: network device
  *
  * Mark device as removed from system and therefore no longer available.
  */
 void netif_device_detach(struct net_device *dev)
 {
     if (test_and_clear_bit(__LINK_STATE_PRESENT, &dev->state) &&
         netif_running(dev)) {
         netif_tx_stop_all_queues(dev);
     }
 }
 EXPORT_SYMBOL(netif_device_detach);
 
 /**
  * netif_device_attach - mark device as attached
  * @dev: network device
  *
  * Mark device as attached from system and restart if needed.
  */
 void netif_device_attach(struct net_device *dev)
 {
     if (!test_and_set_bit(__LINK_STATE_PRESENT, &dev->state) &&
         netif_running(dev)) {
         netif_tx_wake_all_queues(dev);
         __netdev_watchdog_up(dev);
     }
 }
 EXPORT_SYMBOL(netif_device_attach);
 
 /*
  * Returns a Tx hash based on the given packet descriptor a Tx queues' number
  * to be used as a distribution range.
  */
 static u16 skb_tx_hash(const struct net_device *dev,
                const struct net_device *sb_dev,
                struct sk_buff *skb)
 {
     u32 hash;
     u16 qoffset = 0;
     u16 qcount = dev->real_num_tx_queues;
 
     if (dev->num_tc) {
         u8 tc = netdev_get_prio_tc_map(dev, skb->priority);
 
         qoffset = sb_dev->tc_to_txq[tc].offset;
         qcount = sb_dev->tc_to_txq[tc].count;
         if (unlikely(!qcount)) {
             net_warn_ratelimited("%s: invalid qcount, qoffset %u for tc %u\n",
                          sb_dev->name, qoffset, tc);
             qoffset = 0;
             qcount = dev->real_num_tx_queues;
         }
     }
 
     if (skb_rx_queue_recorded(skb)) {
         hash = skb_get_rx_queue(skb);
         if (hash >= qoffset)
             hash -= qoffset;
         while (unlikely(hash >= qcount))
             hash -= qcount;
         return hash + qoffset;
     }
 
     return (u16) reciprocal_scale(skb_get_hash(skb), qcount) + qoffset;
 }
 
 static void skb_warn_bad_offload(const struct sk_buff *skb)
 {
     static const netdev_features_t null_features;
     struct net_device *dev = skb->dev;
     const char *name = "";
 
     if (!net_ratelimit())
         return;
 
     if (dev) {
         if (dev->dev.parent)
             name = dev_driver_string(dev->dev.parent);
         else
             name = netdev_name(dev);
     }
     skb_dump(KERN_WARNING, skb, false);
     WARN(1, "%s: caps=(%pNF, %pNF)\n",
          name, dev ? &dev->features : &null_features,
          skb->sk ? &skb->sk->sk_route_caps : &null_features);
 }
 
 /*
  * Invalidate hardware checksum when packet is to be mangled, and
  * complete checksum manually on outgoing path.
  */
 int skb_checksum_help(struct sk_buff *skb)
 {
     __wsum csum;
     int ret = 0, offset;
 
     if (skb->ip_summed == CHECKSUM_COMPLETE)
         goto out_set_summed;
 
     if (unlikely(skb_is_gso(skb))) {
         skb_warn_bad_offload(skb);
         return -EINVAL;
     }
 
     /* Before computing a checksum, we should make sure no frag could
      * be modified by an external entity : checksum could be wrong.
      */
     if (skb_has_shared_frag(skb)) {
         ret = __skb_linearize(skb);
         if (ret)
             goto out;
     }
 
     offset = skb_checksum_start_offset(skb);
     ret = -EINVAL;
     if (WARN_ON_ONCE(offset >= skb_headlen(skb))) {
         DO_ONCE_LITE(skb_dump, KERN_ERR, skb, false);
         goto out;
     }
     csum = skb_checksum(skb, offset, skb->len - offset, 0);
 
     offset += skb->csum_offset;
     if (WARN_ON_ONCE(offset + sizeof(__sum16) > skb_headlen(skb))) {
         DO_ONCE_LITE(skb_dump, KERN_ERR, skb, false);
         goto out;
     }
     ret = skb_ensure_writable(skb, offset + sizeof(__sum16));
     if (ret)
         goto out;
 
     *(__sum16 *)(skb->data + offset) = csum_fold(csum) ?: CSUM_MANGLED_0;
 out_set_summed:
     skb->ip_summed = CHECKSUM_NONE;
 out:
     return ret;
 }
 EXPORT_SYMBOL(skb_checksum_help);
 
 int skb_crc32c_csum_help(struct sk_buff *skb)
 {
     __le32 crc32c_csum;
     int ret = 0, offset, start;
 
     if (skb->ip_summed != CHECKSUM_PARTIAL)
         goto out;
 
     if (unlikely(skb_is_gso(skb)))
         goto out;
 
     /* Before computing a checksum, we should make sure no frag could
      * be modified by an external entity : checksum could be wrong.
      */
     if (unlikely(skb_has_shared_frag(skb))) {
         ret = __skb_linearize(skb);
         if (ret)
             goto out;
     }
     start = skb_checksum_start_offset(skb);
     offset = start + offsetof(struct sctphdr, checksum);
     if (WARN_ON_ONCE(offset >= skb_headlen(skb))) {
         ret = -EINVAL;
         goto out;
     }
 
     ret = skb_ensure_writable(skb, offset + sizeof(__le32));
     if (ret)
         goto out;
 
     crc32c_csum = cpu_to_le32(~__skb_checksum(skb, start,
                           skb->len - start, ~(__u32)0,
                           crc32c_csum_stub));
     *(__le32 *)(skb->data + offset) = crc32c_csum;
     skb->ip_summed = CHECKSUM_NONE;
     skb->csum_not_inet = 0;
 out:
     return ret;
 }
 
 __be16 skb_network_protocol(struct sk_buff *skb, int *depth)
 {
     __be16 type = skb->protocol;
 
     /* Tunnel gso handlers can set protocol to ethernet. */
     if (type == htons(ETH_P_TEB)) {
         struct ethhdr *eth;
 
         if (unlikely(!pskb_may_pull(skb, sizeof(struct ethhdr))))
             return 0;
 
         eth = (struct ethhdr *)skb->data;
         type = eth->h_proto;
     }
 
     return __vlan_get_protocol(skb, type, depth);
 }
 
 /* openvswitch calls this on rx path, so we need a different check.
  */
 static inline bool skb_needs_check(struct sk_buff *skb, bool tx_path)
 {
     if (tx_path)
         return skb->ip_summed != CHECKSUM_PARTIAL &&
                skb->ip_summed != CHECKSUM_UNNECESSARY;
 
     return skb->ip_summed == CHECKSUM_NONE;
 }
 
 /**
  *  __skb_gso_segment - Perform segmentation on skb.
  *  @skb: buffer to segment
  *  @features: features for the output path (see dev->features)
  *  @tx_path: whether it is called in TX path
  *
  *  This function segments the given skb and returns a list of segments.
  *
  *  It may return NULL if the skb requires no segmentation.  This is
  *  only possible when GSO is used for verifying header integrity.
  *
  *  Segmentation preserves SKB_GSO_CB_OFFSET bytes of previous skb cb.
  */
 struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
                   netdev_features_t features, bool tx_path)
 {
     struct sk_buff *segs;
 
     if (unlikely(skb_needs_check(skb, tx_path))) {
         int err;
 
         /* We're going to init ->check field in TCP or UDP header */
         err = skb_cow_head(skb, 0);
         if (err < 0)
             return ERR_PTR(err);
     }
 
     /* Only report GSO partial support if it will enable us to
      * support segmentation on this frame without needing additional
      * work.
      */
     if (features & NETIF_F_GSO_PARTIAL) {
         netdev_features_t partial_features = NETIF_F_GSO_ROBUST;
         struct net_device *dev = skb->dev;
 
         partial_features |= dev->features & dev->gso_partial_features;
         if (!skb_gso_ok(skb, features | partial_features))
             features &= ~NETIF_F_GSO_PARTIAL;
     }
 
     BUILD_BUG_ON(SKB_GSO_CB_OFFSET +
              sizeof(*SKB_GSO_CB(skb)) > sizeof(skb->cb));
 
     SKB_GSO_CB(skb)->mac_offset = skb_headroom(skb);
     SKB_GSO_CB(skb)->encap_level = 0;
 
     skb_reset_mac_header(skb);
     skb_reset_mac_len(skb);
 
     segs = skb_mac_gso_segment(skb, features);
 
     if (segs != skb && unlikely(skb_needs_check(skb, tx_path) && !IS_ERR(segs)))
         skb_warn_bad_offload(skb);
 
     return segs;
 }
 EXPORT_SYMBOL(__skb_gso_segment);
 
 /* Take action when hardware reception checksum errors are detected. */
 #ifdef CONFIG_BUG
 static void do_netdev_rx_csum_fault(struct net_device *dev, struct sk_buff *skb)
 {
     netdev_err(dev, "hw csum failure\n");
     skb_dump(KERN_ERR, skb, true);
     dump_stack();
 }
 
 void netdev_rx_csum_fault(struct net_device *dev, struct sk_buff *skb)
 {
     DO_ONCE_LITE(do_netdev_rx_csum_fault, dev, skb);
 }
 EXPORT_SYMBOL(netdev_rx_csum_fault);
 #endif
 
 /* XXX: check that highmem exists at all on the given machine. */
 static int illegal_highdma(struct net_device *dev, struct sk_buff *skb)
 {
 #ifdef CONFIG_HIGHMEM
     int i;
 
     if (!(dev->features & NETIF_F_HIGHDMA)) {
         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
             skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 
             if (PageHighMem(skb_frag_page(frag)))
                 return 1;
         }
     }
 #endif
     return 0;
 }
 
 /* If MPLS offload request, verify we are testing hardware MPLS features
  * instead of standard features for the netdev.
  */
 #if IS_ENABLED(CONFIG_NET_MPLS_GSO)
 static netdev_features_t net_mpls_features(struct sk_buff *skb,
                        netdev_features_t features,
                        __be16 type)
 {
     if (eth_p_mpls(type))
         features &= skb->dev->mpls_features;
 
     return features;
 }
 #else
 static netdev_features_t net_mpls_features(struct sk_buff *skb,
                        netdev_features_t features,
                        __be16 type)
 {
     return features;
 }
 #endif
 
 static netdev_features_t harmonize_features(struct sk_buff *skb,
     netdev_features_t features)
 {
     __be16 type;
 
     type = skb_network_protocol(skb, NULL);
     features = net_mpls_features(skb, features, type);
 
     if (skb->ip_summed != CHECKSUM_NONE &&
         !can_checksum_protocol(features, type)) {
         features &= ~(NETIF_F_CSUM_MASK | NETIF_F_GSO_MASK);
     }
     if (illegal_highdma(skb->dev, skb))
         features &= ~NETIF_F_SG;
 
     return features;
 }
 
 netdev_features_t passthru_features_check(struct sk_buff *skb,
                       struct net_device *dev,
                       netdev_features_t features)
 {
     return features;
 }
 EXPORT_SYMBOL(passthru_features_check);
 
 static netdev_features_t dflt_features_check(struct sk_buff *skb,
                          struct net_device *dev,
                          netdev_features_t features)
 {
     return vlan_features_check(skb, features);
 }
 
 static netdev_features_t gso_features_check(const struct sk_buff *skb,
                         struct net_device *dev,
                         netdev_features_t features)
 {
     u16 gso_segs = skb_shinfo(skb)->gso_segs;
 
     if (gso_segs > READ_ONCE(dev->gso_max_segs))
         return features & ~NETIF_F_GSO_MASK;
 
     if (!skb_shinfo(skb)->gso_type) {
         skb_warn_bad_offload(skb);
         return features & ~NETIF_F_GSO_MASK;
     }
 
     /* Support for GSO partial features requires software
      * intervention before we can actually process the packets
      * so we need to strip support for any partial features now
      * and we can pull them back in after we have partially
      * segmented the frame.
      */
     if (!(skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL))
         features &= ~dev->gso_partial_features;
 
     /* Make sure to clear the IPv4 ID mangling feature if the
      * IPv4 header has the potential to be fragmented.
      */
     if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4) {
         struct iphdr *iph = skb->encapsulation ?
                     inner_ip_hdr(skb) : ip_hdr(skb);
 
         if (!(iph->frag_off & htons(IP_DF)))
             features &= ~NETIF_F_TSO_MANGLEID;
     }
 
     return features;
 }
 
 netdev_features_t netif_skb_features(struct sk_buff *skb)
 {
     struct net_device *dev = skb->dev;
     netdev_features_t features = dev->features;
 
     if (skb_is_gso(skb))
         features = gso_features_check(skb, dev, features);
 
     /* If encapsulation offload request, verify we are testing
      * hardware encapsulation features instead of standard
      * features for the netdev
      */
     if (skb->encapsulation)
         features &= dev->hw_enc_features;
 
     if (skb_vlan_tagged(skb))
         features = netdev_intersect_features(features,
                              dev->vlan_features |
                              NETIF_F_HW_VLAN_CTAG_TX |
                              NETIF_F_HW_VLAN_STAG_TX);
 
     if (dev->netdev_ops->ndo_features_check)
         features &= dev->netdev_ops->ndo_features_check(skb, dev,
                                 features);
     else
         features &= dflt_features_check(skb, dev, features);
 
     return harmonize_features(skb, features);
 }
 EXPORT_SYMBOL(netif_skb_features);
 
 static int xmit_one(struct sk_buff *skb, struct net_device *dev,
             struct netdev_queue *txq, bool more)
 {
     unsigned int len;
     int rc;
 
     if (dev_nit_active(dev))
         dev_queue_xmit_nit(skb, dev);
 
     len = skb->len;
     trace_net_dev_start_xmit(skb, dev);
     rc = netdev_start_xmit(skb, dev, txq, more);
     trace_net_dev_xmit(skb, rc, dev, len);
 
     return rc;
 }
 
 struct sk_buff *dev_hard_start_xmit(struct sk_buff *first, struct net_device *dev,
                     struct netdev_queue *txq, int *ret)
 {
     struct sk_buff *skb = first;
     int rc = NETDEV_TX_OK;
 
     while (skb) {
         struct sk_buff *next = skb->next;
 
         skb_mark_not_on_list(skb);
         rc = xmit_one(skb, dev, txq, next != NULL);
         if (unlikely(!dev_xmit_complete(rc))) {
             skb->next = next;
             goto out;
         }
 
         skb = next;
         if (netif_tx_queue_stopped(txq) && skb) {
             rc = NETDEV_TX_BUSY;
             break;
         }
     }
 
 out:
     *ret = rc;
     return skb;
 }
 
 static struct sk_buff *validate_xmit_vlan(struct sk_buff *skb,
                       netdev_features_t features)
 {
     if (skb_vlan_tag_present(skb) &&
         !vlan_hw_offload_capable(features, skb->vlan_proto))
         skb = __vlan_hwaccel_push_inside(skb);
     return skb;
 }
 
 int skb_csum_hwoffload_help(struct sk_buff *skb,
                 const netdev_features_t features)
 {
     if (unlikely(skb_csum_is_sctp(skb)))
         return !!(features & NETIF_F_SCTP_CRC) ? 0 :
             skb_crc32c_csum_help(skb);
 
     if (features & NETIF_F_HW_CSUM)
         return 0;
 
     if (features & (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM)) {
         switch (skb->csum_offset) {
         case offsetof(struct tcphdr, check):
         case offsetof(struct udphdr, check):
             return 0;
         }
     }
 
     return skb_checksum_help(skb);
 }
 EXPORT_SYMBOL(skb_csum_hwoffload_help);
 
 static struct sk_buff *validate_xmit_skb(struct sk_buff *skb, struct net_device *dev, bool *again)
 {
     netdev_features_t features;
 
     features = netif_skb_features(skb);
     skb = validate_xmit_vlan(skb, features);
     if (unlikely(!skb))
         goto out_null;
 
     skb = sk_validate_xmit_skb(skb, dev);
     if (unlikely(!skb))
         goto out_null;
 
     if (netif_needs_gso(skb, features)) {
         struct sk_buff *segs;
 
         segs = skb_gso_segment(skb, features);
         if (IS_ERR(segs)) {
             goto out_kfree_skb;
         } else if (segs) {
             consume_skb(skb);
             skb = segs;
         }
     } else {
         if (skb_needs_linearize(skb, features) &&
             __skb_linearize(skb))
             goto out_kfree_skb;
 
         /* If packet is not checksummed and device does not
          * support checksumming for this protocol, complete
          * checksumming here.
          */
         if (skb->ip_summed == CHECKSUM_PARTIAL) {
             if (skb->encapsulation)
                 skb_set_inner_transport_header(skb,
                                    skb_checksum_start_offset(skb));
             else
                 skb_set_transport_header(skb,
                              skb_checksum_start_offset(skb));
             if (skb_csum_hwoffload_help(skb, features))
                 goto out_kfree_skb;
         }
     }
 
     skb = validate_xmit_xfrm(skb, features, again);
 
     return skb;
 
 out_kfree_skb:
     kfree_skb(skb);
 out_null:
     dev_core_stats_tx_dropped_inc(dev);
     return NULL;
 }
 
 struct sk_buff *validate_xmit_skb_list(struct sk_buff *skb, struct net_device *dev, bool *again)
 {
     struct sk_buff *next, *head = NULL, *tail;
 
     for (; skb != NULL; skb = next) {
         next = skb->next;
         skb_mark_not_on_list(skb);
 
         /* in case skb wont be segmented, point to itself */
         skb->prev = skb;
 
         skb = validate_xmit_skb(skb, dev, again);
         if (!skb)
             continue;
 
         if (!head)
             head = skb;
         else
             tail->next = skb;
         /* If skb was segmented, skb->prev points to
          * the last segment. If not, it still contains skb.
          */
         tail = skb->prev;
     }
     return head;
 }
 EXPORT_SYMBOL_GPL(validate_xmit_skb_list);
 
 static void qdisc_pkt_len_init(struct sk_buff *skb)
 {
     const struct skb_shared_info *shinfo = skb_shinfo(skb);
 
     qdisc_skb_cb(skb)->pkt_len = skb->len;
 
     /* To get more precise estimation of bytes sent on wire,
      * we add to pkt_len the headers size of all segments
      */
     if (shinfo->gso_size && skb_transport_header_was_set(skb)) {
         unsigned int hdr_len;
         u16 gso_segs = shinfo->gso_segs;
 
         /* mac layer + network layer */
         hdr_len = skb_transport_header(skb) - skb_mac_header(skb);
 
         /* + transport layer */
         if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) {
             const struct tcphdr *th;
             struct tcphdr _tcphdr;
 
             th = skb_header_pointer(skb, skb_transport_offset(skb),
                         sizeof(_tcphdr), &_tcphdr);
             if (likely(th))
                 hdr_len += __tcp_hdrlen(th);
         } else {
             struct udphdr _udphdr;
 
             if (skb_header_pointer(skb, skb_transport_offset(skb),
                            sizeof(_udphdr), &_udphdr))
                 hdr_len += sizeof(struct udphdr);
         }
 
         if (shinfo->gso_type & SKB_GSO_DODGY)
             gso_segs = DIV_ROUND_UP(skb->len - hdr_len,
                         shinfo->gso_size);
 
         qdisc_skb_cb(skb)->pkt_len += (gso_segs - 1) * hdr_len;
     }
 }
 
 static int dev_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *q,
                  struct sk_buff **to_free,
                  struct netdev_queue *txq)
 {
     int rc;
 
     rc = q->enqueue(skb, q, to_free) & NET_XMIT_MASK;
     if (rc == NET_XMIT_SUCCESS)
         trace_qdisc_enqueue(q, txq, skb);
     return rc;
 }
 
 static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
                  struct net_device *dev,
                  struct netdev_queue *txq)
 {
     spinlock_t *root_lock = qdisc_lock(q);
     struct sk_buff *to_free = NULL;
     bool contended;
     int rc;
 
     qdisc_calculate_pkt_len(skb, q);
 
     if (q->flags & TCQ_F_NOLOCK) {
         if (q->flags & TCQ_F_CAN_BYPASS && nolock_qdisc_is_empty(q) &&
             qdisc_run_begin(q)) {
             /* Retest nolock_qdisc_is_empty() within the protection
              * of q->seqlock to protect from racing with requeuing.
              */
             if (unlikely(!nolock_qdisc_is_empty(q))) {
                 rc = dev_qdisc_enqueue(skb, q, &to_free, txq);
                 __qdisc_run(q);
                 qdisc_run_end(q);
 
                 goto no_lock_out;
             }
 
             qdisc_bstats_cpu_update(q, skb);
             if (sch_direct_xmit(skb, q, dev, txq, NULL, true) &&
                 !nolock_qdisc_is_empty(q))
                 __qdisc_run(q);
 
             qdisc_run_end(q);
             return NET_XMIT_SUCCESS;
         }
 
         rc = dev_qdisc_enqueue(skb, q, &to_free, txq);
         qdisc_run(q);
 
 no_lock_out:
         if (unlikely(to_free))
             kfree_skb_list_reason(to_free,
                           SKB_DROP_REASON_QDISC_DROP);
         return rc;
     }
 
     /*
      * Heuristic to force contended enqueues to serialize on a
      * separate lock before trying to get qdisc main lock.
      * This permits qdisc->running owner to get the lock more
      * often and dequeue packets faster.
      * On PREEMPT_RT it is possible to preempt the qdisc owner during xmit
      * and then other tasks will only enqueue packets. The packets will be
      * sent after the qdisc owner is scheduled again. To prevent this
      * scenario the task always serialize on the lock.
      */
     contended = qdisc_is_running(q) || IS_ENABLED(CONFIG_PREEMPT_RT);
     if (unlikely(contended))
         spin_lock(&q->busylock);
 
     spin_lock(root_lock);
     if (unlikely(test_bit(__QDISC_STATE_DEACTIVATED, &q->state))) {
         __qdisc_drop(skb, &to_free);
         rc = NET_XMIT_DROP;
     } else if ((q->flags & TCQ_F_CAN_BYPASS) && !qdisc_qlen(q) &&
            qdisc_run_begin(q)) {
         /*
          * This is a work-conserving queue; there are no old skbs
          * waiting to be sent out; and the qdisc is not running -
          * xmit the skb directly.
          */
 
         qdisc_bstats_update(q, skb);
 
         if (sch_direct_xmit(skb, q, dev, txq, root_lock, true)) {
             if (unlikely(contended)) {
                 spin_unlock(&q->busylock);
                 contended = false;
             }
             __qdisc_run(q);
         }
 
         qdisc_run_end(q);
         rc = NET_XMIT_SUCCESS;
     } else {
         rc = dev_qdisc_enqueue(skb, q, &to_free, txq);
         if (qdisc_run_begin(q)) {
             if (unlikely(contended)) {
                 spin_unlock(&q->busylock);
                 contended = false;
             }
             __qdisc_run(q);
             qdisc_run_end(q);
         }
     }
     spin_unlock(root_lock);
     if (unlikely(to_free))
         kfree_skb_list_reason(to_free, SKB_DROP_REASON_QDISC_DROP);
     if (unlikely(contended))
         spin_unlock(&q->busylock);
     return rc;
 }
 
 #if IS_ENABLED(CONFIG_CGROUP_NET_PRIO)
 static void skb_update_prio(struct sk_buff *skb)
 {
     const struct netprio_map *map;
     const struct sock *sk;
     unsigned int prioidx;
 
     if (skb->priority)
         return;
     map = rcu_dereference_bh(skb->dev->priomap);
     if (!map)
         return;
     sk = skb_to_full_sk(skb);
     if (!sk)
         return;
 
     prioidx = sock_cgroup_prioidx(&sk->sk_cgrp_data);
 
     if (prioidx < map->priomap_len)
         skb->priority = map->priomap[prioidx];
 }
 #else
 #define skb_update_prio(skb)
 #endif
 
 /**
  *  dev_loopback_xmit - loop back @skb
  *  @net: network namespace this loopback is happening in
  *  @sk:  sk needed to be a netfilter okfn
  *  @skb: buffer to transmit
  */
 int dev_loopback_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
     skb_reset_mac_header(skb);
     __skb_pull(skb, skb_network_offset(skb));
     skb->pkt_type = PACKET_LOOPBACK;
     if (skb->ip_summed == CHECKSUM_NONE)
         skb->ip_summed = CHECKSUM_UNNECESSARY;
     DEBUG_NET_WARN_ON_ONCE(!skb_dst(skb));
     skb_dst_force(skb);
     netif_rx(skb);
     return 0;
 }
 EXPORT_SYMBOL(dev_loopback_xmit);
 
 #ifdef CONFIG_NET_EGRESS
 static struct sk_buff *
 sch_handle_egress(struct sk_buff *skb, int *ret, struct net_device *dev)
 {
 #ifdef CONFIG_NET_CLS_ACT
     struct mini_Qdisc *miniq = rcu_dereference_bh(dev->miniq_egress);
     struct tcf_result cl_res;
 
     if (!miniq)
         return skb;
 
     /* qdisc_skb_cb(skb)->pkt_len was already set by the caller. */
     tc_skb_cb(skb)->mru = 0;
     tc_skb_cb(skb)->post_ct = false;
     mini_qdisc_bstats_cpu_update(miniq, skb);
 
     switch (tcf_classify(skb, miniq->block, miniq->filter_list, &cl_res, false)) {
     case TC_ACT_OK:
     case TC_ACT_RECLASSIFY:
         skb->tc_index = TC_H_MIN(cl_res.classid);
         break;
     case TC_ACT_SHOT:
         mini_qdisc_qstats_cpu_drop(miniq);
         *ret = NET_XMIT_DROP;
         kfree_skb_reason(skb, SKB_DROP_REASON_TC_EGRESS);
         return NULL;
     case TC_ACT_STOLEN:
     case TC_ACT_QUEUED:
     case TC_ACT_TRAP:
         *ret = NET_XMIT_SUCCESS;
         consume_skb(skb);
         return NULL;
     case TC_ACT_REDIRECT:
         /* No need to push/pop skb's mac_header here on egress! */
         skb_do_redirect(skb);
         *ret = NET_XMIT_SUCCESS;
         return NULL;
     default:
         break;
     }
 #endif /* CONFIG_NET_CLS_ACT */
 
     return skb;
 }
 
 static struct netdev_queue *
 netdev_tx_queue_mapping(struct net_device *dev, struct sk_buff *skb)
 {
     int qm = skb_get_queue_mapping(skb);
 
     return netdev_get_tx_queue(dev, netdev_cap_txqueue(dev, qm));
 }
 
 static bool netdev_xmit_txqueue_skipped(void)
 {
     return __this_cpu_read(softnet_data.xmit.skip_txqueue);
 }
 
 void netdev_xmit_skip_txqueue(bool skip)
 {
     __this_cpu_write(softnet_data.xmit.skip_txqueue, skip);
 }
 EXPORT_SYMBOL_GPL(netdev_xmit_skip_txqueue);
 #endif /* CONFIG_NET_EGRESS */
 
 #ifdef CONFIG_XPS
 static int __get_xps_queue_idx(struct net_device *dev, struct sk_buff *skb,
                    struct xps_dev_maps *dev_maps, unsigned int tci)
 {
     int tc = netdev_get_prio_tc_map(dev, skb->priority);
     struct xps_map *map;
     int queue_index = -1;
 
     if (tc >= dev_maps->num_tc || tci >= dev_maps->nr_ids)
         return queue_index;
 
     tci *= dev_maps->num_tc;
     tci += tc;
 
     map = rcu_dereference(dev_maps->attr_map[tci]);
     if (map) {
         if (map->len == 1)
             queue_index = map->queues[0];
         else
             queue_index = map->queues[reciprocal_scale(
                         skb_get_hash(skb), map->len)];
         if (unlikely(queue_index >= dev->real_num_tx_queues))
             queue_index = -1;
     }
     return queue_index;
 }
 #endif
 
 static int get_xps_queue(struct net_device *dev, struct net_device *sb_dev,
              struct sk_buff *skb)
 {
 #ifdef CONFIG_XPS
     struct xps_dev_maps *dev_maps;
     struct sock *sk = skb->sk;
     int queue_index = -1;
 
     if (!static_key_false(&xps_needed))
         return -1;
 
     rcu_read_lock();
     if (!static_key_false(&xps_rxqs_needed))
         goto get_cpus_map;
 
     dev_maps = rcu_dereference(sb_dev->xps_maps[XPS_RXQS]);
     if (dev_maps) {
         int tci = sk_rx_queue_get(sk);
 
         if (tci >= 0)
             queue_index = __get_xps_queue_idx(dev, skb, dev_maps,
                               tci);
     }
 
 get_cpus_map:
     if (queue_index < 0) {
         dev_maps = rcu_dereference(sb_dev->xps_maps[XPS_CPUS]);
         if (dev_maps) {
             unsigned int tci = skb->sender_cpu - 1;
 
             queue_index = __get_xps_queue_idx(dev, skb, dev_maps,
                               tci);
         }
     }
     rcu_read_unlock();
 
     return queue_index;
 #else
     return -1;
 #endif
 }
 
 u16 dev_pick_tx_zero(struct net_device *dev, struct sk_buff *skb,
              struct net_device *sb_dev)
 {
     return 0;
 }
 EXPORT_SYMBOL(dev_pick_tx_zero);
 
 u16 dev_pick_tx_cpu_id(struct net_device *dev, struct sk_buff *skb,
                struct net_device *sb_dev)
 {
     return (u16)raw_smp_processor_id() % dev->real_num_tx_queues;
 }
 EXPORT_SYMBOL(dev_pick_tx_cpu_id);
 
 u16 netdev_pick_tx(struct net_device *dev, struct sk_buff *skb,
              struct net_device *sb_dev)
 {
     struct sock *sk = skb->sk;
     int queue_index = sk_tx_queue_get(sk);
 
     sb_dev = sb_dev ? : dev;
 
     if (queue_index < 0 || skb->ooo_okay ||
         queue_index >= dev->real_num_tx_queues) {
         int new_index = get_xps_queue(dev, sb_dev, skb);
 
         if (new_index < 0)
             new_index = skb_tx_hash(dev, sb_dev, skb);
 
         if (queue_index != new_index && sk &&
             sk_fullsock(sk) &&
             rcu_access_pointer(sk->sk_dst_cache))
             sk_tx_queue_set(sk, new_index);
 
         queue_index = new_index;
     }
 
     return queue_index;
 }
 EXPORT_SYMBOL(netdev_pick_tx);
 
 struct netdev_queue *netdev_core_pick_tx(struct net_device *dev,
                      struct sk_buff *skb,
                      struct net_device *sb_dev)
 {
     int queue_index = 0;
 
 #ifdef CONFIG_XPS
     u32 sender_cpu = skb->sender_cpu - 1;
 
     if (sender_cpu >= (u32)NR_CPUS)
         skb->sender_cpu = raw_smp_processor_id() + 1;
 #endif
 
     if (dev->real_num_tx_queues != 1) {
         const struct net_device_ops *ops = dev->netdev_ops;
 
         if (ops->ndo_select_queue)
             queue_index = ops->ndo_select_queue(dev, skb, sb_dev);
         else
             queue_index = netdev_pick_tx(dev, skb, sb_dev);
 
         queue_index = netdev_cap_txqueue(dev, queue_index);
     }
 
     skb_set_queue_mapping(skb, queue_index);
     return netdev_get_tx_queue(dev, queue_index);
 }
 
 /**
  * __dev_queue_xmit() - transmit a buffer
  * @skb:    buffer to transmit
  * @sb_dev: suboordinate device used for L2 forwarding offload
  *
  * Queue a buffer for transmission to a network device. The caller must
  * have set the device and priority and built the buffer before calling
  * this function. The function can be called from an interrupt.
  *
  * When calling this method, interrupts MUST be enabled. This is because
  * the BH enable code must have IRQs enabled so that it will not deadlock.
  *
  * Regardless of the return value, the skb is consumed, so it is currently
  * difficult to retry a send to this method. (You can bump the ref count
  * before sending to hold a reference for retry if you are careful.)
  *
  * Return:
  * * 0              - buffer successfully transmitted
  * * positive qdisc return code - NET_XMIT_DROP etc.
  * * negative errno     - other errors
  */
 int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev)
 {
     struct net_device *dev = skb->dev;
     struct netdev_queue *txq = NULL;
     struct Qdisc *q;
     int rc = -ENOMEM;
     bool again = false;
 
     skb_reset_mac_header(skb);
     skb_assert_len(skb);
 
     if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP))
         __skb_tstamp_tx(skb, NULL, NULL, skb->sk, SCM_TSTAMP_SCHED);
 
     /* Disable soft irqs for various locks below. Also
      * stops preemption for RCU.
      */
     rcu_read_lock_bh();
 
     skb_update_prio(skb);
 
     qdisc_pkt_len_init(skb);
 #ifdef CONFIG_NET_CLS_ACT
     skb->tc_at_ingress = 0;
 #endif
 #ifdef CONFIG_NET_EGRESS
     if (static_branch_unlikely(&egress_needed_key)) {
         if (nf_hook_egress_active()) {
             skb = nf_hook_egress(skb, &rc, dev);
             if (!skb)
                 goto out;
         }
 
         netdev_xmit_skip_txqueue(false);
 
         nf_skip_egress(skb, true);
         skb = sch_handle_egress(skb, &rc, dev);
         if (!skb)
             goto out;
         nf_skip_egress(skb, false);
 
         if (netdev_xmit_txqueue_skipped())
             txq = netdev_tx_queue_mapping(dev, skb);
     }
 #endif
     /* If device/qdisc don't need skb->dst, release it right now while
      * its hot in this cpu cache.
      */
     if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
         skb_dst_drop(skb);
     else
         skb_dst_force(skb);
 
     if (!txq)
         txq = netdev_core_pick_tx(dev, skb, sb_dev);
 
     q = rcu_dereference_bh(txq->qdisc);
 
     trace_net_dev_queue(skb);
     if (q->enqueue) {
         rc = __dev_xmit_skb(skb, q, dev, txq);
         goto out;
     }
 
     /* The device has no queue. Common case for software devices:
      * loopback, all the sorts of tunnels...
 
      * Really, it is unlikely that netif_tx_lock protection is necessary
      * here.  (f.e. loopback and IP tunnels are clean ignoring statistics
      * counters.)
      * However, it is possible, that they rely on protection
      * made by us here.
 
      * Check this and shot the lock. It is not prone from deadlocks.
      *Either shot noqueue qdisc, it is even simpler 8)
      */
     if (dev->flags & IFF_UP) {
         int cpu = smp_processor_id(); /* ok because BHs are off */
 
         /* Other cpus might concurrently change txq->xmit_lock_owner
          * to -1 or to their cpu id, but not to our id.
          */
         if (READ_ONCE(txq->xmit_lock_owner) != cpu) {
             if (dev_xmit_recursion())
                 goto recursion_alert;
 
             skb = validate_xmit_skb(skb, dev, &again);
             if (!skb)
                 goto out;
 
             HARD_TX_LOCK(dev, txq, cpu);
 
             if (!netif_xmit_stopped(txq)) {
                 dev_xmit_recursion_inc();
                 skb = dev_hard_start_xmit(skb, dev, txq, &rc);
                 dev_xmit_recursion_dec();
                 if (dev_xmit_complete(rc)) {
                     HARD_TX_UNLOCK(dev, txq);
                     goto out;
                 }
             }
             HARD_TX_UNLOCK(dev, txq);
             net_crit_ratelimited("Virtual device %s asks to queue packet!\n",
                          dev->name);
         } else {
             /* Recursion is detected! It is possible,
              * unfortunately
              */
 recursion_alert:
             net_crit_ratelimited("Dead loop on virtual device %s, fix it urgently!\n",
                          dev->name);
         }
     }
 
     rc = -ENETDOWN;
     rcu_read_unlock_bh();
 
     dev_core_stats_tx_dropped_inc(dev);
     kfree_skb_list(skb);
     return rc;
 out:
     rcu_read_unlock_bh();
     return rc;
 }
 EXPORT_SYMBOL(__dev_queue_xmit);
 
 int __dev_direct_xmit(struct sk_buff *skb, u16 queue_id)
 {
     struct net_device *dev = skb->dev;
     struct sk_buff *orig_skb = skb;
     struct netdev_queue *txq;
     int ret = NETDEV_TX_BUSY;
     bool again = false;
 
     if (unlikely(!netif_running(dev) ||
              !netif_carrier_ok(dev)))
         goto drop;
 
     skb = validate_xmit_skb_list(skb, dev, &again);
     if (skb != orig_skb)
         goto drop;
 
     skb_set_queue_mapping(skb, queue_id);
     txq = skb_get_tx_queue(dev, skb);
 
     local_bh_disable();
 
     dev_xmit_recursion_inc();
     HARD_TX_LOCK(dev, txq, smp_processor_id());
     if (!netif_xmit_frozen_or_drv_stopped(txq))
         ret = netdev_start_xmit(skb, dev, txq, false);
     HARD_TX_UNLOCK(dev, txq);
     dev_xmit_recursion_dec();
 
     local_bh_enable();
     return ret;
 drop:
     dev_core_stats_tx_dropped_inc(dev);
     kfree_skb_list(skb);
     return NET_XMIT_DROP;
 }
 EXPORT_SYMBOL(__dev_direct_xmit);
 
 /*************************************************************************
  *          Receiver routines
  *************************************************************************/
 
 int netdev_max_backlog __read_mostly = 1000;
 EXPORT_SYMBOL(netdev_max_backlog);
 
 int netdev_tstamp_prequeue __read_mostly = 1;
 unsigned int sysctl_skb_defer_max __read_mostly = 64;
 int netdev_budget __read_mostly = 300;
 /* Must be at least 2 jiffes to guarantee 1 jiffy timeout */
 unsigned int __read_mostly netdev_budget_usecs = 2 * USEC_PER_SEC / HZ;
 int weight_p __read_mostly = 64;           /* old backlog weight */
 int dev_weight_rx_bias __read_mostly = 1;  /* bias for backlog weight */
 int dev_weight_tx_bias __read_mostly = 1;  /* bias for output_queue quota */
 int dev_rx_weight __read_mostly = 64;
 int dev_tx_weight __read_mostly = 64;
 
 /* Called with irq disabled */
 static inline void ____napi_schedule(struct softnet_data *sd,
                      struct napi_struct *napi)
 {
     struct task_struct *thread;
 
     lockdep_assert_irqs_disabled();
 
     if (test_bit(NAPI_STATE_THREADED, &napi->state)) {
         /* Paired with smp_mb__before_atomic() in
          * napi_enable()/dev_set_threaded().
          * Use READ_ONCE() to guarantee a complete
          * read on napi->thread. Only call
          * wake_up_process() when it's not NULL.
          */
         thread = READ_ONCE(napi->thread);
         if (thread) {
             /* Avoid doing set_bit() if the thread is in
              * INTERRUPTIBLE state, cause napi_thread_wait()
              * makes sure to proceed with napi polling
              * if the thread is explicitly woken from here.
              */
             if (READ_ONCE(thread->__state) != TASK_INTERRUPTIBLE)
                 set_bit(NAPI_STATE_SCHED_THREADED, &napi->state);
             wake_up_process(thread);
             return;
         }
     }
 
     list_add_tail(&napi->poll_list, &sd->poll_list);
     __raise_softirq_irqoff(NET_RX_SOFTIRQ);
 }
 
 #ifdef CONFIG_RPS
 
 /* One global table that all flow-based protocols share. */
 struct rps_sock_flow_table __rcu *rps_sock_flow_table __read_mostly;
 EXPORT_SYMBOL(rps_sock_flow_table);
 u32 rps_cpu_mask __read_mostly;
 EXPORT_SYMBOL(rps_cpu_mask);
 
 struct static_key_false rps_needed __read_mostly;
 EXPORT_SYMBOL(rps_needed);
 struct static_key_false rfs_needed __read_mostly;
 EXPORT_SYMBOL(rfs_needed);
 
 static struct rps_dev_flow *
 set_rps_cpu(struct net_device *dev, struct sk_buff *skb,
         struct rps_dev_flow *rflow, u16 next_cpu)
 {
     if (next_cpu < nr_cpu_ids) {
 #ifdef CONFIG_RFS_ACCEL
         struct netdev_rx_queue *rxqueue;
         struct rps_dev_flow_table *flow_table;
         struct rps_dev_flow *old_rflow;
         u32 flow_id;
         u16 rxq_index;
         int rc;
 
         /* Should we steer this flow to a different hardware queue? */
         if (!skb_rx_queue_recorded(skb) || !dev->rx_cpu_rmap ||
             !(dev->features & NETIF_F_NTUPLE))
             goto out;
         rxq_index = cpu_rmap_lookup_index(dev->rx_cpu_rmap, next_cpu);
         if (rxq_index == skb_get_rx_queue(skb))
             goto out;
 
         rxqueue = dev->_rx + rxq_index;
         flow_table = rcu_dereference(rxqueue->rps_flow_table);
         if (!flow_table)
             goto out;
         flow_id = skb_get_hash(skb) & flow_table->mask;
         rc = dev->netdev_ops->ndo_rx_flow_steer(dev, skb,
                             rxq_index, flow_id);
         if (rc < 0)
             goto out;
         old_rflow = rflow;
         rflow = &flow_table->flows[flow_id];
         rflow->filter = rc;
         if (old_rflow->filter == rflow->filter)
             old_rflow->filter = RPS_NO_FILTER;
     out:
 #endif
         rflow->last_qtail =
             per_cpu(softnet_data, next_cpu).input_queue_head;
     }
 
     rflow->cpu = next_cpu;
     return rflow;
 }
 
 /*
  * get_rps_cpu is called from netif_receive_skb and returns the target
  * CPU from the RPS map of the receiving queue for a given skb.
  * rcu_read_lock must be held on entry.
  */
 static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
                struct rps_dev_flow **rflowp)
 {
     const struct rps_sock_flow_table *sock_flow_table;
     struct netdev_rx_queue *rxqueue = dev->_rx;
     struct rps_dev_flow_table *flow_table;
     struct rps_map *map;
     int cpu = -1;
     u32 tcpu;
     u32 hash;
 
     if (skb_rx_queue_recorded(skb)) {
         u16 index = skb_get_rx_queue(skb);
 
         if (unlikely(index >= dev->real_num_rx_queues)) {
             WARN_ONCE(dev->real_num_rx_queues > 1,
                   "%s received packet on queue %u, but number "
                   "of RX queues is %u\n",
                   dev->name, index, dev->real_num_rx_queues);
             goto done;
         }
         rxqueue += index;
     }
 
     /* Avoid computing hash if RFS/RPS is not active for this rxqueue */
 
     flow_table = rcu_dereference(rxqueue->rps_flow_table);
     map = rcu_dereference(rxqueue->rps_map);
     if (!flow_table && !map)
         goto done;
 
     skb_reset_network_header(skb);
     hash = skb_get_hash(skb);
     if (!hash)
         goto done;
 
     sock_flow_table = rcu_dereference(rps_sock_flow_table);
     if (flow_table && sock_flow_table) {
         struct rps_dev_flow *rflow;
         u32 next_cpu;
         u32 ident;
 
         /* First check into global flow table if there is a match */
         ident = sock_flow_table->ents[hash & sock_flow_table->mask];
         if ((ident ^ hash) & ~rps_cpu_mask)
             goto try_rps;
 
         next_cpu = ident & rps_cpu_mask;
 
         /* OK, now we know there is a match,
          * we can look at the local (per receive queue) flow table
          */
         rflow = &flow_table->flows[hash & flow_table->mask];
         tcpu = rflow->cpu;
 
         /*
          * If the desired CPU (where last recvmsg was done) is
          * different from current CPU (one in the rx-queue flow
          * table entry), switch if one of the following holds:
          *   - Current CPU is unset (>= nr_cpu_ids).
          *   - Current CPU is offline.
          *   - The current CPU's queue tail has advanced beyond the
          *     last packet that was enqueued using this table entry.
          *     This guarantees that all previous packets for the flow
          *     have been dequeued, thus preserving in order delivery.
          */
         if (unlikely(tcpu != next_cpu) &&
             (tcpu >= nr_cpu_ids || !cpu_online(tcpu) ||
              ((int)(per_cpu(softnet_data, tcpu).input_queue_head -
               rflow->last_qtail)) >= 0)) {
             tcpu = next_cpu;
             rflow = set_rps_cpu(dev, skb, rflow, next_cpu);
         }
 
         if (tcpu < nr_cpu_ids && cpu_online(tcpu)) {
             *rflowp = rflow;
             cpu = tcpu;
             goto done;
         }
     }
 
 try_rps:
 
     if (map) {
         tcpu = map->cpus[reciprocal_scale(hash, map->len)];
         if (cpu_online(tcpu)) {
             cpu = tcpu;
             goto done;
         }
     }
 
 done:
     return cpu;
 }
 
 #ifdef CONFIG_RFS_ACCEL
 
 /**
  * rps_may_expire_flow - check whether an RFS hardware filter may be removed
  * @dev: Device on which the filter was set
  * @rxq_index: RX queue index
  * @flow_id: Flow ID passed to ndo_rx_flow_steer()
  * @filter_id: Filter ID returned by ndo_rx_flow_steer()
  *
  * Drivers that implement ndo_rx_flow_steer() should periodically call
  * this function for each installed filter and remove the filters for
  * which it returns %true.
  */
 bool rps_may_expire_flow(struct net_device *dev, u16 rxq_index,
              u32 flow_id, u16 filter_id)
 {
     struct netdev_rx_queue *rxqueue = dev->_rx + rxq_index;
     struct rps_dev_flow_table *flow_table;
     struct rps_dev_flow *rflow;
     bool expire = true;
     unsigned int cpu;
 
     rcu_read_lock();
     flow_table = rcu_dereference(rxqueue->rps_flow_table);
     if (flow_table && flow_id <= flow_table->mask) {
         rflow = &flow_table->flows[flow_id];
         cpu = READ_ONCE(rflow->cpu);
         if (rflow->filter == filter_id && cpu < nr_cpu_ids &&
             ((int)(per_cpu(softnet_data, cpu).input_queue_head -
                rflow->last_qtail) <
              (int)(10 * flow_table->mask)))
             expire = false;
     }
     rcu_read_unlock();
     return expire;
 }
 EXPORT_SYMBOL(rps_may_expire_flow);
 
 #endif /* CONFIG_RFS_ACCEL */
 
 /* Called from hardirq (IPI) context */
 static void rps_trigger_softirq(void *data)
 {
     struct softnet_data *sd = data;
 
     ____napi_schedule(sd, &sd->backlog);
     sd->received_rps++;
 }
 
 #endif /* CONFIG_RPS */
 
 /* Called from hardirq (IPI) context */
 static void trigger_rx_softirq(void *data)
 {
     struct softnet_data *sd = data;
 
     __raise_softirq_irqoff(NET_RX_SOFTIRQ);
     smp_store_release(&sd->defer_ipi_scheduled, 0);
 }
 
 /*
  * Check if this softnet_data structure is another cpu one
  * If yes, queue it to our IPI list and return 1
  * If no, return 0
  */
 static int napi_schedule_rps(struct softnet_data *sd)
 {
     struct softnet_data *mysd = this_cpu_ptr(&softnet_data);
 
 #ifdef CONFIG_RPS
     if (sd != mysd) {
         sd->rps_ipi_next = mysd->rps_ipi_list;
         mysd->rps_ipi_list = sd;
 
         __raise_softirq_irqoff(NET_RX_SOFTIRQ);
         return 1;
     }
 #endif /* CONFIG_RPS */
     __napi_schedule_irqoff(&mysd->backlog);
     return 0;
 }
 
 #ifdef CONFIG_NET_FLOW_LIMIT
 int netdev_flow_limit_table_len __read_mostly = (1 << 12);
 #endif
 
 static bool skb_flow_limit(struct sk_buff *skb, unsigned int qlen)
 {
 #ifdef CONFIG_NET_FLOW_LIMIT
     struct sd_flow_limit *fl;
     struct softnet_data *sd;
     unsigned int old_flow, new_flow;
 
     if (qlen < (READ_ONCE(netdev_max_backlog) >> 1))
         return false;
 
     sd = this_cpu_ptr(&softnet_data);
 
     rcu_read_lock();
     fl = rcu_dereference(sd->flow_limit);
     if (fl) {
         new_flow = skb_get_hash(skb) & (fl->num_buckets - 1);
         old_flow = fl->history[fl->history_head];
         fl->history[fl->history_head] = new_flow;
 
         fl->history_head++;
         fl->history_head &= FLOW_LIMIT_HISTORY - 1;
 
         if (likely(fl->buckets[old_flow]))
             fl->buckets[old_flow]--;
 
         if (++fl->buckets[new_flow] > (FLOW_LIMIT_HISTORY >> 1)) {
             fl->count++;
             rcu_read_unlock();
             return true;
         }
     }
     rcu_read_unlock();
 #endif
     return false;
 }
 
 /*
  * enqueue_to_backlog is called to queue an skb to a per CPU backlog
  * queue (may be a remote CPU queue).
  */
 static int enqueue_to_backlog(struct sk_buff *skb, int cpu,
                   unsigned int *qtail)
 {
     enum skb_drop_reason reason;
     struct softnet_data *sd;
     unsigned long flags;
     unsigned int qlen;
 
     reason = SKB_DROP_REASON_NOT_SPECIFIED;
     sd = &per_cpu(softnet_data, cpu);
 
     rps_lock_irqsave(sd, &flags);
     if (!netif_running(skb->dev))
         goto drop;
     qlen = skb_queue_len(&sd->input_pkt_queue);
     if (qlen <= READ_ONCE(netdev_max_backlog) && !skb_flow_limit(skb, qlen)) {
         if (qlen) {
 enqueue:
             __skb_queue_tail(&sd->input_pkt_queue, skb);
             input_queue_tail_incr_save(sd, qtail);
             rps_unlock_irq_restore(sd, &flags);
             return NET_RX_SUCCESS;
         }
 
         /* Schedule NAPI for backlog device
          * We can use non atomic operation since we own the queue lock
          */
         if (!__test_and_set_bit(NAPI_STATE_SCHED, &sd->backlog.state))
             napi_schedule_rps(sd);
         goto enqueue;
     }
     reason = SKB_DROP_REASON_CPU_BACKLOG;
 
 drop:
     sd->dropped++;
     rps_unlock_irq_restore(sd, &flags);
 
     dev_core_stats_rx_dropped_inc(skb->dev);
     kfree_skb_reason(skb, reason);
     return NET_RX_DROP;
 }
 
 static struct netdev_rx_queue *netif_get_rxqueue(struct sk_buff *skb)
 {
     struct net_device *dev = skb->dev;
     struct netdev_rx_queue *rxqueue;
 
     rxqueue = dev->_rx;
 
     if (skb_rx_queue_recorded(skb)) {
         u16 index = skb_get_rx_queue(skb);
 
         if (unlikely(index >= dev->real_num_rx_queues)) {
             WARN_ONCE(dev->real_num_rx_queues > 1,
                   "%s received packet on queue %u, but number "
                   "of RX queues is %u\n",
                   dev->name, index, dev->real_num_rx_queues);
 
             return rxqueue; /* Return first rxqueue */
         }
         rxqueue += index;
     }
     return rxqueue;
 }
 
 u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
                  struct bpf_prog *xdp_prog)
 {
     void *orig_data, *orig_data_end, *hard_start;
     struct netdev_rx_queue *rxqueue;
     bool orig_bcast, orig_host;
     u32 mac_len, frame_sz;
     __be16 orig_eth_type;
     struct ethhdr *eth;
     u32 metalen, act;
     int off;
 
     /* The XDP program wants to see the packet starting at the MAC
      * header.
      */
     mac_len = skb->data - skb_mac_header(skb);
     hard_start = skb->data - skb_headroom(skb);
 
     /* SKB "head" area always have tailroom for skb_shared_info */
     frame_sz = (void *)skb_end_pointer(skb) - hard_start;
     frame_sz += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 
     rxqueue = netif_get_rxqueue(skb);
     xdp_init_buff(xdp, frame_sz, &rxqueue->xdp_rxq);
     xdp_prepare_buff(xdp, hard_start, skb_headroom(skb) - mac_len,
              skb_headlen(skb) + mac_len, true);
 
     orig_data_end = xdp->data_end;
     orig_data = xdp->data;
     eth = (struct ethhdr *)xdp->data;
     orig_host = ether_addr_equal_64bits(eth->h_dest, skb->dev->dev_addr);
     orig_bcast = is_multicast_ether_addr_64bits(eth->h_dest);
     orig_eth_type = eth->h_proto;
 
     act = bpf_prog_run_xdp(xdp_prog, xdp);
 
     /* check if bpf_xdp_adjust_head was used */
     off = xdp->data - orig_data;
     if (off) {
         if (off > 0)
             __skb_pull(skb, off);
         else if (off < 0)
             __skb_push(skb, -off);
 
         skb->mac_header += off;
         skb_reset_network_header(skb);
     }
 
     /* check if bpf_xdp_adjust_tail was used */
     off = xdp->data_end - orig_data_end;
     if (off != 0) {
         skb_set_tail_pointer(skb, xdp->data_end - xdp->data);
         skb->len += off; /* positive on grow, negative on shrink */
     }
 
     /* check if XDP changed eth hdr such SKB needs update */
     eth = (struct ethhdr *)xdp->data;
     if ((orig_eth_type != eth->h_proto) ||
         (orig_host != ether_addr_equal_64bits(eth->h_dest,
                           skb->dev->dev_addr)) ||
         (orig_bcast != is_multicast_ether_addr_64bits(eth->h_dest))) {
         __skb_push(skb, ETH_HLEN);
         skb->pkt_type = PACKET_HOST;
         skb->protocol = eth_type_trans(skb, skb->dev);
     }
 
     /* Redirect/Tx gives L2 packet, code that will reuse skb must __skb_pull
      * before calling us again on redirect path. We do not call do_redirect
      * as we leave that up to the caller.
      *
      * Caller is responsible for managing lifetime of skb (i.e. calling
      * kfree_skb in response to actions it cannot handle/XDP_DROP).
      */
     switch (act) {
     case XDP_REDIRECT:
     case XDP_TX:
         __skb_push(skb, mac_len);
         break;
     case XDP_PASS:
         metalen = xdp->data - xdp->data_meta;
         if (metalen)
             skb_metadata_set(skb, metalen);
         break;
     }
 
     return act;
 }
 
 static u32 netif_receive_generic_xdp(struct sk_buff *skb,
                      struct xdp_buff *xdp,
                      struct bpf_prog *xdp_prog)
 {
     u32 act = XDP_DROP;
 
     /* Reinjected packets coming from act_mirred or similar should
      * not get XDP generic processing.
      */
     if (skb_is_redirected(skb))
         return XDP_PASS;
 
     /* XDP packets must be linear and must have sufficient headroom
      * of XDP_PACKET_HEADROOM bytes. This is the guarantee that also
      * native XDP provides, thus we need to do it here as well.
      */
     if (skb_cloned(skb) || skb_is_nonlinear(skb) ||
         skb_headroom(skb) < XDP_PACKET_HEADROOM) {
         int hroom = XDP_PACKET_HEADROOM - skb_headroom(skb);
         int troom = skb->tail + skb->data_len - skb->end;
 
         /* In case we have to go down the path and also linearize,
          * then lets do the pskb_expand_head() work just once here.
          */
         if (pskb_expand_head(skb,
                      hroom > 0 ? ALIGN(hroom, NET_SKB_PAD) : 0,
                      troom > 0 ? troom + 128 : 0, GFP_ATOMIC))
             goto do_drop;
         if (skb_linearize(skb))
             goto do_drop;
     }
 
     act = bpf_prog_run_generic_xdp(skb, xdp, xdp_prog);
     switch (act) {
     case XDP_REDIRECT:
     case XDP_TX:
     case XDP_PASS:
         break;
     default:
         bpf_warn_invalid_xdp_action(skb->dev, xdp_prog, act);
         fallthrough;
     case XDP_ABORTED:
         trace_xdp_exception(skb->dev, xdp_prog, act);
         fallthrough;
     case XDP_DROP:
     do_drop:
         kfree_skb(skb);
         break;
     }
 
     return act;
 }
 
 /* When doing generic XDP we have to bypass the qdisc layer and the
  * network taps in order to match in-driver-XDP behavior. This also means
  * that XDP packets are able to starve other packets going through a qdisc,
  * and DDOS attacks will be more effective. In-driver-XDP use dedicated TX
  * queues, so they do not have this starvation issue.
  */
 void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog)
 {
     struct net_device *dev = skb->dev;
     struct netdev_queue *txq;
     bool free_skb = true;
     int cpu, rc;
 
     txq = netdev_core_pick_tx(dev, skb, NULL);
     cpu = smp_processor_id();
     HARD_TX_LOCK(dev, txq, cpu);
     if (!netif_xmit_frozen_or_drv_stopped(txq)) {
         rc = netdev_start_xmit(skb, dev, txq, 0);
         if (dev_xmit_complete(rc))
             free_skb = false;
     }
     HARD_TX_UNLOCK(dev, txq);
     if (free_skb) {
         trace_xdp_exception(dev, xdp_prog, XDP_TX);
         dev_core_stats_tx_dropped_inc(dev);
         kfree_skb(skb);
     }
 }
 
 static DEFINE_STATIC_KEY_FALSE(generic_xdp_needed_key);
 
 int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb)
 {
     if (xdp_prog) {
         struct xdp_buff xdp;
         u32 act;
         int err;
 
         act = netif_receive_generic_xdp(skb, &xdp, xdp_prog);
         if (act != XDP_PASS) {
             switch (act) {
             case XDP_REDIRECT:
                 err = xdp_do_generic_redirect(skb->dev, skb,
                                   &xdp, xdp_prog);
                 if (err)
                     goto out_redir;
                 break;
             case XDP_TX:
                 generic_xdp_tx(skb, xdp_prog);
                 break;
             }
             return XDP_DROP;
         }
     }
     return XDP_PASS;
 out_redir:
     kfree_skb_reason(skb, SKB_DROP_REASON_XDP);
     return XDP_DROP;
 }
 EXPORT_SYMBOL_GPL(do_xdp_generic);
 
 static int netif_rx_internal(struct sk_buff *skb)
 {
     int ret;
 
     net_timestamp_check(READ_ONCE(netdev_tstamp_prequeue), skb);
 
     trace_netif_rx(skb);
 
 #ifdef CONFIG_RPS
     if (static_branch_unlikely(&rps_needed)) {
         struct rps_dev_flow voidflow, *rflow = &voidflow;
         int cpu;
 
         rcu_read_lock();
 
         cpu = get_rps_cpu(skb->dev, skb, &rflow);
         if (cpu < 0)
             cpu = smp_processor_id();
 
         ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
 
         rcu_read_unlock();
     } else
 #endif
     {
         unsigned int qtail;
 
         ret = enqueue_to_backlog(skb, smp_processor_id(), &qtail);
     }
     return ret;
 }
 
 /**
  *  __netif_rx  -   Slightly optimized version of netif_rx
  *  @skb: buffer to post
  *
  *  This behaves as netif_rx except that it does not disable bottom halves.
  *  As a result this function may only be invoked from the interrupt context
  *  (either hard or soft interrupt).
  */
 int __netif_rx(struct sk_buff *skb)
 {
     int ret;
 
     lockdep_assert_once(hardirq_count() | softirq_count());
 
     trace_netif_rx_entry(skb);
     ret = netif_rx_internal(skb);
     trace_netif_rx_exit(ret);
     return ret;
 }
 EXPORT_SYMBOL(__netif_rx);
 
 /**
  *  netif_rx    -   post buffer to the network code
  *  @skb: buffer to post
  *
  *  This function receives a packet from a device driver and queues it for
  *  the upper (protocol) levels to process via the backlog NAPI device. It
  *  always succeeds. The buffer may be dropped during processing for
  *  congestion control or by the protocol layers.
  *  The network buffer is passed via the backlog NAPI device. Modern NIC
  *  driver should use NAPI and GRO.
  *  This function can used from interrupt and from process context. The
  *  caller from process context must not disable interrupts before invoking
  *  this function.
  *
  *  return values:
  *  NET_RX_SUCCESS  (no congestion)
  *  NET_RX_DROP     (packet was dropped)
  *
  */
 int netif_rx(struct sk_buff *skb)
 {
     bool need_bh_off = !(hardirq_count() | softirq_count());
     int ret;
 
     if (need_bh_off)
         local_bh_disable();
     trace_netif_rx_entry(skb);
     ret = netif_rx_internal(skb);
     trace_netif_rx_exit(ret);
     if (need_bh_off)
         local_bh_enable();
     return ret;
 }
 EXPORT_SYMBOL(netif_rx);
 
 static __latent_entropy void net_tx_action(struct softirq_action *h)
 {
     struct softnet_data *sd = this_cpu_ptr(&softnet_data);
 
     if (sd->completion_queue) {
         struct sk_buff *clist;
 
         local_irq_disable();
         clist = sd->completion_queue;
         sd->completion_queue = NULL;
         local_irq_enable();
 
         while (clist) {
             struct sk_buff *skb = clist;
 
             clist = clist->next;
 
             WARN_ON(refcount_read(&skb->users));
             if (likely(get_kfree_skb_cb(skb)->reason == SKB_REASON_CONSUMED))
                 trace_consume_skb(skb);
             else
                 trace_kfree_skb(skb, net_tx_action,
                         SKB_DROP_REASON_NOT_SPECIFIED);
 
             if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
                 __kfree_skb(skb);
             else
                 __kfree_skb_defer(skb);
         }
     }
 
     if (sd->output_queue) {
         struct Qdisc *head;
 
         local_irq_disable();
         head = sd->output_queue;
         sd->output_queue = NULL;
         sd->output_queue_tailp = &sd->output_queue;
         local_irq_enable();
 
         rcu_read_lock();
 
         while (head) {
             struct Qdisc *q = head;
             spinlock_t *root_lock = NULL;
 
             head = head->next_sched;
 
             /* We need to make sure head->next_sched is read
              * before clearing __QDISC_STATE_SCHED
              */
             smp_mb__before_atomic();
 
             if (!(q->flags & TCQ_F_NOLOCK)) {
                 root_lock = qdisc_lock(q);
                 spin_lock(root_lock);
             } else if (unlikely(test_bit(__QDISC_STATE_DEACTIVATED,
                              &q->state))) {
                 /* There is a synchronize_net() between
                  * STATE_DEACTIVATED flag being set and
                  * qdisc_reset()/some_qdisc_is_busy() in
                  * dev_deactivate(), so we can safely bail out
                  * early here to avoid data race between
                  * qdisc_deactivate() and some_qdisc_is_busy()
                  * for lockless qdisc.
                  */
                 clear_bit(__QDISC_STATE_SCHED, &q->state);
                 continue;
             }
 
             clear_bit(__QDISC_STATE_SCHED, &q->state);
             qdisc_run(q);
             if (root_lock)
                 spin_unlock(root_lock);
         }
 
         rcu_read_unlock();
     }
 
     xfrm_dev_backlog(sd);
 }
 
 #if IS_ENABLED(CONFIG_BRIDGE) && IS_ENABLED(CONFIG_ATM_LANE)
 /* This hook is defined here for ATM LANE */
 int (*br_fdb_test_addr_hook)(struct net_device *dev,
                  unsigned char *addr) __read_mostly;
 EXPORT_SYMBOL_GPL(br_fdb_test_addr_hook);
 #endif
 
 static inline struct sk_buff *
 sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret,
            struct net_device *orig_dev, bool *another)
 {
 #ifdef CONFIG_NET_CLS_ACT
     struct mini_Qdisc *miniq = rcu_dereference_bh(skb->dev->miniq_ingress);
     struct tcf_result cl_res;
 
     /* If there's at least one ingress present somewhere (so
      * we get here via enabled static key), remaining devices
      * that are not configured with an ingress qdisc will bail
      * out here.
      */
     if (!miniq)
         return skb;
 
     if (*pt_prev) {
         *ret = deliver_skb(skb, *pt_prev, orig_dev);
         *pt_prev = NULL;
     }
 
     qdisc_skb_cb(skb)->pkt_len = skb->len;
     tc_skb_cb(skb)->mru = 0;
     tc_skb_cb(skb)->post_ct = false;
     skb->tc_at_ingress = 1;
     mini_qdisc_bstats_cpu_update(miniq, skb);
 
     switch (tcf_classify(skb, miniq->block, miniq->filter_list, &cl_res, false)) {
     case TC_ACT_OK:
     case TC_ACT_RECLASSIFY:
         skb->tc_index = TC_H_MIN(cl_res.classid);
         break;
     case TC_ACT_SHOT:
         mini_qdisc_qstats_cpu_drop(miniq);
         kfree_skb_reason(skb, SKB_DROP_REASON_TC_INGRESS);
         return NULL;
     case TC_ACT_STOLEN:
     case TC_ACT_QUEUED:
     case TC_ACT_TRAP:
         consume_skb(skb);
         return NULL;
     case TC_ACT_REDIRECT:
         /* skb_mac_header check was done by cls/act_bpf, so
          * we can safely push the L2 header back before
          * redirecting to another netdev
          */
         __skb_push(skb, skb->mac_len);
         if (skb_do_redirect(skb) == -EAGAIN) {
             __skb_pull(skb, skb->mac_len);
             *another = true;
             break;
         }
         return NULL;
     case TC_ACT_CONSUMED:
         return NULL;
     default:
         break;
     }
 #endif /* CONFIG_NET_CLS_ACT */
     return skb;
 }
 
 /**
  *  netdev_is_rx_handler_busy - check if receive handler is registered
  *  @dev: device to check
  *
  *  Check if a receive handler is already registered for a given device.
  *  Return true if there one.
  *
  *  The caller must hold the rtnl_mutex.
  */
 bool netdev_is_rx_handler_busy(struct net_device *dev)
 {
     ASSERT_RTNL();
     return dev && rtnl_dereference(dev->rx_handler);
 }
 EXPORT_SYMBOL_GPL(netdev_is_rx_handler_busy);
 
 /**
  *  netdev_rx_handler_register - register receive handler
  *  @dev: device to register a handler for
  *  @rx_handler: receive handler to register
  *  @rx_handler_data: data pointer that is used by rx handler
  *
  *  Register a receive handler for a device. This handler will then be
  *  called from __netif_receive_skb. A negative errno code is returned
  *  on a failure.
  *
  *  The caller must hold the rtnl_mutex.
  *
  *  For a general description of rx_handler, see enum rx_handler_result.
  */
 int netdev_rx_handler_register(struct net_device *dev,
                    rx_handler_func_t *rx_handler,
                    void *rx_handler_data)
 {
     if (netdev_is_rx_handler_busy(dev))
         return -EBUSY;
 
     if (dev->priv_flags & IFF_NO_RX_HANDLER)
         return -EINVAL;
 
     /* Note: rx_handler_data must be set before rx_handler */
     rcu_assign_pointer(dev->rx_handler_data, rx_handler_data);
     rcu_assign_pointer(dev->rx_handler, rx_handler);
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(netdev_rx_handler_register);
 
 /**
  *  netdev_rx_handler_unregister - unregister receive handler
  *  @dev: device to unregister a handler from
  *
  *  Unregister a receive handler from a device.
  *
  *  The caller must hold the rtnl_mutex.
  */
 void netdev_rx_handler_unregister(struct net_device *dev)
 {
 
     ASSERT_RTNL();
     RCU_INIT_POINTER(dev->rx_handler, NULL);
     /* a reader seeing a non NULL rx_handler in a rcu_read_lock()
      * section has a guarantee to see a non NULL rx_handler_data
      * as well.
      */
     synchronize_net();
     RCU_INIT_POINTER(dev->rx_handler_data, NULL);
 }
 EXPORT_SYMBOL_GPL(netdev_rx_handler_unregister);
 
 /*
  * Limit the use of PFMEMALLOC reserves to those protocols that implement
  * the special handling of PFMEMALLOC skbs.
  */
 static bool skb_pfmemalloc_protocol(struct sk_buff *skb)
 {
     switch (skb->protocol) {
     case htons(ETH_P_ARP):
     case htons(ETH_P_IP):
     case htons(ETH_P_IPV6):
     case htons(ETH_P_8021Q):
     case htons(ETH_P_8021AD):
         return true;
     default:
         return false;
     }
 }
 
 static inline int nf_ingress(struct sk_buff *skb, struct packet_type **pt_prev,
                  int *ret, struct net_device *orig_dev)
 {
     if (nf_hook_ingress_active(skb)) {
         int ingress_retval;
 
         if (*pt_prev) {
             *ret = deliver_skb(skb, *pt_prev, orig_dev);
             *pt_prev = NULL;
         }
 
         rcu_read_lock();
         ingress_retval = nf_hook_ingress(skb);
         rcu_read_unlock();
         return ingress_retval;
     }
     return 0;
 }
 
 static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc,
                     struct packet_type **ppt_prev)
 {
     struct packet_type *ptype, *pt_prev;
     rx_handler_func_t *rx_handler;
     struct sk_buff *skb = *pskb;
     struct net_device *orig_dev;
     bool deliver_exact = false;
     int ret = NET_RX_DROP;
     __be16 type;
 
     net_timestamp_check(!READ_ONCE(netdev_tstamp_prequeue), skb);
 
     trace_netif_receive_skb(skb);
 
     orig_dev = skb->dev;
 
     skb_reset_network_header(skb);
     if (!skb_transport_header_was_set(skb))
         skb_reset_transport_header(skb);
     skb_reset_mac_len(skb);
 
     pt_prev = NULL;
 
 another_round:
     skb->skb_iif = skb->dev->ifindex;
 
     __this_cpu_inc(softnet_data.processed);
 
     if (static_branch_unlikely(&generic_xdp_needed_key)) {
         int ret2;
 
         migrate_disable();
         ret2 = do_xdp_generic(rcu_dereference(skb->dev->xdp_prog), skb);
         migrate_enable();
 
         if (ret2 != XDP_PASS) {
             ret = NET_RX_DROP;
             goto out;
         }
     }
 
     if (eth_type_vlan(skb->protocol)) {
         skb = skb_vlan_untag(skb);
         if (unlikely(!skb))
             goto out;
     }
 
     if (skb_skip_tc_classify(skb))
         goto skip_classify;
 
     if (pfmemalloc)
         goto skip_taps;
 
     list_for_each_entry_rcu(ptype, &ptype_all, list) {
         if (pt_prev)
             ret = deliver_skb(skb, pt_prev, orig_dev);
         pt_prev = ptype;
     }
 
     list_for_each_entry_rcu(ptype, &skb->dev->ptype_all, list) {
         if (pt_prev)
             ret = deliver_skb(skb, pt_prev, orig_dev);
         pt_prev = ptype;
     }
 
 skip_taps:
 #ifdef CONFIG_NET_INGRESS
     if (static_branch_unlikely(&ingress_needed_key)) {
         bool another = false;
 
         nf_skip_egress(skb, true);
         skb = sch_handle_ingress(skb, &pt_prev, &ret, orig_dev,
                      &another);
         if (another)
             goto another_round;
         if (!skb)
             goto out;
 
         nf_skip_egress(skb, false);
         if (nf_ingress(skb, &pt_prev, &ret, orig_dev) < 0)
             goto out;
     }
 #endif
     skb_reset_redirect(skb);
 skip_classify:
     if (pfmemalloc && !skb_pfmemalloc_protocol(skb))
         goto drop;
 
     if (skb_vlan_tag_present(skb)) {
         if (pt_prev) {
             ret = deliver_skb(skb, pt_prev, orig_dev);
             pt_prev = NULL;
         }
         if (vlan_do_receive(&skb))
             goto another_round;
         else if (unlikely(!skb))
             goto out;
     }
 
     rx_handler = rcu_dereference(skb->dev->rx_handler);
     if (rx_handler) {
         if (pt_prev) {
             ret = deliver_skb(skb, pt_prev, orig_dev);
             pt_prev = NULL;
         }
         switch (rx_handler(&skb)) {
         case RX_HANDLER_CONSUMED:
             ret = NET_RX_SUCCESS;
             goto out;
         case RX_HANDLER_ANOTHER:
             goto another_round;
         case RX_HANDLER_EXACT:
             deliver_exact = true;
             break;
         case RX_HANDLER_PASS:
             break;
         default:
             BUG();
         }
     }
 
     if (unlikely(skb_vlan_tag_present(skb)) && !netdev_uses_dsa(skb->dev)) {
 check_vlan_id:
         if (skb_vlan_tag_get_id(skb)) {
             /* Vlan id is non 0 and vlan_do_receive() above couldn't
              * find vlan device.
              */
             skb->pkt_type = PACKET_OTHERHOST;
         } else if (eth_type_vlan(skb->protocol)) {
             /* Outer header is 802.1P with vlan 0, inner header is
              * 802.1Q or 802.1AD and vlan_do_receive() above could
              * not find vlan dev for vlan id 0.
              */
             __vlan_hwaccel_clear_tag(skb);
             skb = skb_vlan_untag(skb);
             if (unlikely(!skb))
                 goto out;
             if (vlan_do_receive(&skb))
                 /* After stripping off 802.1P header with vlan 0
                  * vlan dev is found for inner header.
                  */
                 goto another_round;
             else if (unlikely(!skb))
                 goto out;
             else
                 /* We have stripped outer 802.1P vlan 0 header.
                  * But could not find vlan dev.
                  * check again for vlan id to set OTHERHOST.
                  */
                 goto check_vlan_id;
         }
         /* Note: we might in the future use prio bits
          * and set skb->priority like in vlan_do_receive()
          * For the time being, just ignore Priority Code Point
          */
         __vlan_hwaccel_clear_tag(skb);
     }
 
     type = skb->protocol;
 
     /* deliver only exact match when indicated */
     if (likely(!deliver_exact)) {
         deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
                        &ptype_base[ntohs(type) &
                            PTYPE_HASH_MASK]);
     }
 
     deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
                    &orig_dev->ptype_specific);
 
     if (unlikely(skb->dev != orig_dev)) {
         deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
                        &skb->dev->ptype_specific);
     }
 
     if (pt_prev) {
         if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC)))
             goto drop;
         *ppt_prev = pt_prev;
     } else {
 drop:
         if (!deliver_exact)
             dev_core_stats_rx_dropped_inc(skb->dev);
         else
             dev_core_stats_rx_nohandler_inc(skb->dev);
         kfree_skb_reason(skb, SKB_DROP_REASON_UNHANDLED_PROTO);
         /* Jamal, now you will not able to escape explaining
          * me how you were going to use this. :-)
          */
         ret = NET_RX_DROP;
     }
 
 out:
     /* The invariant here is that if *ppt_prev is not NULL
      * then skb should also be non-NULL.
      *
      * Apparently *ppt_prev assignment above holds this invariant due to
      * skb dereferencing near it.
      */
     *pskb = skb;
     return ret;
 }
 
 static int __netif_receive_skb_one_core(struct sk_buff *skb, bool pfmemalloc)
 {
     struct net_device *orig_dev = skb->dev;
     struct packet_type *pt_prev = NULL;
     int ret;
 
     ret = __netif_receive_skb_core(&skb, pfmemalloc, &pt_prev);
     if (pt_prev)
         ret = INDIRECT_CALL_INET(pt_prev->func, ipv6_rcv, ip_rcv, skb,
                      skb->dev, pt_prev, orig_dev);
     return ret;
 }
 
 /**
  *  netif_receive_skb_core - special purpose version of netif_receive_skb
  *  @skb: buffer to process
  *
  *  More direct receive version of netif_receive_skb().  It should
  *  only be used by callers that have a need to skip RPS and Generic XDP.
  *  Caller must also take care of handling if ``(page_is_)pfmemalloc``.
  *
  *  This function may only be called from softirq context and interrupts
  *  should be enabled.
  *
  *  Return values (usually ignored):
  *  NET_RX_SUCCESS: no congestion
  *  NET_RX_DROP: packet was dropped
  */
 int netif_receive_skb_core(struct sk_buff *skb)
 {
     int ret;
 
     rcu_read_lock();
     ret = __netif_receive_skb_one_core(skb, false);
     rcu_read_unlock();
 
     return ret;
 }
 EXPORT_SYMBOL(netif_receive_skb_core);
 
 static inline void __netif_receive_skb_list_ptype(struct list_head *head,
                           struct packet_type *pt_prev,
                           struct net_device *orig_dev)
 {
     struct sk_buff *skb, *next;
 
     if (!pt_prev)
         return;
     if (list_empty(head))
         return;
     if (pt_prev->list_func != NULL)
         INDIRECT_CALL_INET(pt_prev->list_func, ipv6_list_rcv,
                    ip_list_rcv, head, pt_prev, orig_dev);
     else
         list_for_each_entry_safe(skb, next, head, list) {
             skb_list_del_init(skb);
             pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
         }
 }
 
 static void __netif_receive_skb_list_core(struct list_head *head, bool pfmemalloc)
 {
     /* Fast-path assumptions:
      * - There is no RX handler.
      * - Only one packet_type matches.
      * If either of these fails, we will end up doing some per-packet
      * processing in-line, then handling the 'last ptype' for the whole
      * sublist.  This can't cause out-of-order delivery to any single ptype,
      * because the 'last ptype' must be constant across the sublist, and all
      * other ptypes are handled per-packet.
      */
     /* Current (common) ptype of sublist */
     struct packet_type *pt_curr = NULL;
     /* Current (common) orig_dev of sublist */
     struct net_device *od_curr = NULL;
     struct list_head sublist;
     struct sk_buff *skb, *next;
 
     INIT_LIST_HEAD(&sublist);
     list_for_each_entry_safe(skb, next, head, list) {
         struct net_device *orig_dev = skb->dev;
         struct packet_type *pt_prev = NULL;
 
         skb_list_del_init(skb);
         __netif_receive_skb_core(&skb, pfmemalloc, &pt_prev);
         if (!pt_prev)
             continue;
         if (pt_curr != pt_prev || od_curr != orig_dev) {
             /* dispatch old sublist */
             __netif_receive_skb_list_ptype(&sublist, pt_curr, od_curr);
             /* start new sublist */
             INIT_LIST_HEAD(&sublist);
             pt_curr = pt_prev;
             od_curr = orig_dev;
         }
         list_add_tail(&skb->list, &sublist);
     }
 
     /* dispatch final sublist */
     __netif_receive_skb_list_ptype(&sublist, pt_curr, od_curr);
 }
 
 static int __netif_receive_skb(struct sk_buff *skb)
 {
     int ret;
 
     if (sk_memalloc_socks() && skb_pfmemalloc(skb)) {
         unsigned int noreclaim_flag;
 
         /*
          * PFMEMALLOC skbs are special, they should
          * - be delivered to SOCK_MEMALLOC sockets only
          * - stay away from userspace
          * - have bounded memory usage
          *
          * Use PF_MEMALLOC as this saves us from propagating the allocation
          * context down to all allocation sites.
          */
         noreclaim_flag = memalloc_noreclaim_save();
         ret = __netif_receive_skb_one_core(skb, true);
         memalloc_noreclaim_restore(noreclaim_flag);
     } else
         ret = __netif_receive_skb_one_core(skb, false);
 
     return ret;
 }
 
 static void __netif_receive_skb_list(struct list_head *head)
 {
     unsigned long noreclaim_flag = 0;
     struct sk_buff *skb, *next;
     bool pfmemalloc = false; /* Is current sublist PF_MEMALLOC? */
 
     list_for_each_entry_safe(skb, next, head, list) {
         if ((sk_memalloc_socks() && skb_pfmemalloc(skb)) != pfmemalloc) {
             struct list_head sublist;
 
             /* Handle the previous sublist */
             list_cut_before(&sublist, head, &skb->list);
             if (!list_empty(&sublist))
                 __netif_receive_skb_list_core(&sublist, pfmemalloc);
             pfmemalloc = !pfmemalloc;
             /* See comments in __netif_receive_skb */
             if (pfmemalloc)
                 noreclaim_flag = memalloc_noreclaim_save();
             else
                 memalloc_noreclaim_restore(noreclaim_flag);
         }
     }
     /* Handle the remaining sublist */
     if (!list_empty(head))
         __netif_receive_skb_list_core(head, pfmemalloc);
     /* Restore pflags */
     if (pfmemalloc)
         memalloc_noreclaim_restore(noreclaim_flag);
 }
 
 static int generic_xdp_install(struct net_device *dev, struct netdev_bpf *xdp)
 {
     struct bpf_prog *old = rtnl_dereference(dev->xdp_prog);
     struct bpf_prog *new = xdp->prog;
     int ret = 0;
 
     switch (xdp->command) {
     case XDP_SETUP_PROG:
         rcu_assign_pointer(dev->xdp_prog, new);
         if (old)
             bpf_prog_put(old);
 
         if (old && !new) {
             static_branch_dec(&generic_xdp_needed_key);
         } else if (new && !old) {
             static_branch_inc(&generic_xdp_needed_key);
             dev_disable_lro(dev);
             dev_disable_gro_hw(dev);
         }
         break;
 
     default:
         ret = -EINVAL;
         break;
     }
 
     return ret;
 }
 
 static int netif_receive_skb_internal(struct sk_buff *skb)
 {
     int ret;
 
     net_timestamp_check(READ_ONCE(netdev_tstamp_prequeue), skb);
 
     if (skb_defer_rx_timestamp(skb))
         return NET_RX_SUCCESS;
 
     rcu_read_lock();
 #ifdef CONFIG_RPS
     if (static_branch_unlikely(&rps_needed)) {
         struct rps_dev_flow voidflow, *rflow = &voidflow;
         int cpu = get_rps_cpu(skb->dev, skb, &rflow);
 
         if (cpu >= 0) {
             ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
             rcu_read_unlock();
             return ret;
         }
     }
 #endif
     ret = __netif_receive_skb(skb);
     rcu_read_unlock();
     return ret;
 }
 
 void netif_receive_skb_list_internal(struct list_head *head)
 {
     struct sk_buff *skb, *next;
     struct list_head sublist;
 
     INIT_LIST_HEAD(&sublist);
     list_for_each_entry_safe(skb, next, head, list) {
         net_timestamp_check(READ_ONCE(netdev_tstamp_prequeue), skb);
         skb_list_del_init(skb);
         if (!skb_defer_rx_timestamp(skb))
             list_add_tail(&skb->list, &sublist);
     }
     list_splice_init(&sublist, head);
 
     rcu_read_lock();
 #ifdef CONFIG_RPS
     if (static_branch_unlikely(&rps_needed)) {
         list_for_each_entry_safe(skb, next, head, list) {
             struct rps_dev_flow voidflow, *rflow = &voidflow;
             int cpu = get_rps_cpu(skb->dev, skb, &rflow);
 
             if (cpu >= 0) {
                 /* Will be handled, remove from list */
                 skb_list_del_init(skb);
                 enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
             }
         }
     }
 #endif
     __netif_receive_skb_list(head);
     rcu_read_unlock();
 }
 
 /**
  *  netif_receive_skb - process receive buffer from network
  *  @skb: buffer to process
  *
  *  netif_receive_skb() is the main receive data processing function.
  *  It always succeeds. The buffer may be dropped during processing
  *  for congestion control or by the protocol layers.
  *
  *  This function may only be called from softirq context and interrupts
  *  should be enabled.
  *
  *  Return values (usually ignored):
  *  NET_RX_SUCCESS: no congestion
  *  NET_RX_DROP: packet was dropped
  */
 int netif_receive_skb(struct sk_buff *skb)
 {
     int ret;
 
     trace_netif_receive_skb_entry(skb);
 
     ret = netif_receive_skb_internal(skb);
     trace_netif_receive_skb_exit(ret);
 
     return ret;
 }
 EXPORT_SYMBOL(netif_receive_skb);
 
 /**
  *  netif_receive_skb_list - process many receive buffers from network
  *  @head: list of skbs to process.
  *
  *  Since return value of netif_receive_skb() is normally ignored, and
  *  wouldn't be meaningful for a list, this function returns void.
  *
  *  This function may only be called from softirq context and interrupts
  *  should be enabled.
  */
 void netif_receive_skb_list(struct list_head *head)
 {
     struct sk_buff *skb;
 
     if (list_empty(head))
         return;
     if (trace_netif_receive_skb_list_entry_enabled()) {
         list_for_each_entry(skb, head, list)
             trace_netif_receive_skb_list_entry(skb);
     }
     netif_receive_skb_list_internal(head);
     trace_netif_receive_skb_list_exit(0);
 }
 EXPORT_SYMBOL(netif_receive_skb_list);
 
 static DEFINE_PER_CPU(struct work_struct, flush_works);
 
 /* Network device is going away, flush any packets still pending */
 static void flush_backlog(struct work_struct *work)
 {
     struct sk_buff *skb, *tmp;
     struct softnet_data *sd;
 
     local_bh_disable();
     sd = this_cpu_ptr(&softnet_data);
 
     rps_lock_irq_disable(sd);
     skb_queue_walk_safe(&sd->input_pkt_queue, skb, tmp) {
         if (skb->dev->reg_state == NETREG_UNREGISTERING) {
             __skb_unlink(skb, &sd->input_pkt_queue);
             dev_kfree_skb_irq(skb);
             input_queue_head_incr(sd);
         }
     }
     rps_unlock_irq_enable(sd);
 
     skb_queue_walk_safe(&sd->process_queue, skb, tmp) {
         if (skb->dev->reg_state == NETREG_UNREGISTERING) {
             __skb_unlink(skb, &sd->process_queue);
             kfree_skb(skb);
             input_queue_head_incr(sd);
         }
     }
     local_bh_enable();
 }
 
 static bool flush_required(int cpu)
 {
 #if IS_ENABLED(CONFIG_RPS)
     struct softnet_data *sd = &per_cpu(softnet_data, cpu);
     bool do_flush;
 
     rps_lock_irq_disable(sd);
 
     /* as insertion into process_queue happens with the rps lock held,
      * process_queue access may race only with dequeue
      */
     do_flush = !skb_queue_empty(&sd->input_pkt_queue) ||
            !skb_queue_empty_lockless(&sd->process_queue);
     rps_unlock_irq_enable(sd);
 
     return do_flush;
 #endif
     /* without RPS we can't safely check input_pkt_queue: during a
      * concurrent remote skb_queue_splice() we can detect as empty both
      * input_pkt_queue and process_queue even if the latter could end-up
      * containing a lot of packets.
      */
     return true;
 }
 
 static void flush_all_backlogs(void)
 {
     static cpumask_t flush_cpus;
     unsigned int cpu;
 
     /* since we are under rtnl lock protection we can use static data
      * for the cpumask and avoid allocating on stack the possibly
      * large mask
      */
     ASSERT_RTNL();
 
     cpus_read_lock();
 
     cpumask_clear(&flush_cpus);
     for_each_online_cpu(cpu) {
         if (flush_required(cpu)) {
             queue_work_on(cpu, system_highpri_wq,
                       per_cpu_ptr(&flush_works, cpu));
             cpumask_set_cpu(cpu, &flush_cpus);
         }
     }
 
     /* we can have in flight packet[s] on the cpus we are not flushing,
      * synchronize_net() in unregister_netdevice_many() will take care of
      * them
      */
     for_each_cpu(cpu, &flush_cpus)
         flush_work(per_cpu_ptr(&flush_works, cpu));
 
     cpus_read_unlock();
 }
 
 static void net_rps_send_ipi(struct softnet_data *remsd)
 {
 #ifdef CONFIG_RPS
     while (remsd) {
         struct softnet_data *next = remsd->rps_ipi_next;
 
         if (cpu_online(remsd->cpu))
             smp_call_function_single_async(remsd->cpu, &remsd->csd);
         remsd = next;
     }
 #endif
 }
 
 /*
  * net_rps_action_and_irq_enable sends any pending IPI's for rps.
  * Note: called with local irq disabled, but exits with local irq enabled.
  */
 static void net_rps_action_and_irq_enable(struct softnet_data *sd)
 {
 #ifdef CONFIG_RPS
     struct softnet_data *remsd = sd->rps_ipi_list;
 
     if (remsd) {
         sd->rps_ipi_list = NULL;
 
         local_irq_enable();
 
         /* Send pending IPI's to kick RPS processing on remote cpus. */
         net_rps_send_ipi(remsd);
     } else
 #endif
         local_irq_enable();
 }
 
 static bool sd_has_rps_ipi_waiting(struct softnet_data *sd)
 {
 #ifdef CONFIG_RPS
     return sd->rps_ipi_list != NULL;
 #else
     return false;
 #endif
 }
 
 static int process_backlog(struct napi_struct *napi, int quota)
 {
     struct softnet_data *sd = container_of(napi, struct softnet_data, backlog);
     bool again = true;
     int work = 0;
 
     /* Check if we have pending ipi, its better to send them now,
      * not waiting net_rx_action() end.
      */
     if (sd_has_rps_ipi_waiting(sd)) {
         local_irq_disable();
         net_rps_action_and_irq_enable(sd);
     }
 
     napi->weight = READ_ONCE(dev_rx_weight);
     while (again) {
         struct sk_buff *skb;
 
         while ((skb = __skb_dequeue(&sd->process_queue))) {
             rcu_read_lock();
             __netif_receive_skb(skb);
             rcu_read_unlock();
             input_queue_head_incr(sd);
             if (++work >= quota)
                 return work;
 
         }
 
         rps_lock_irq_disable(sd);
         if (skb_queue_empty(&sd->input_pkt_queue)) {
             /*
              * Inline a custom version of __napi_complete().
              * only current cpu owns and manipulates this napi,
              * and NAPI_STATE_SCHED is the only possible flag set
              * on backlog.
              * We can use a plain write instead of clear_bit(),
              * and we dont need an smp_mb() memory barrier.
              */
             napi->state = 0;
             again = false;
         } else {
             skb_queue_splice_tail_init(&sd->input_pkt_queue,
                            &sd->process_queue);
         }
         rps_unlock_irq_enable(sd);
     }
 
     return work;
 }
 
 /**
  * __napi_schedule - schedule for receive
  * @n: entry to schedule
  *
  * The entry's receive function will be scheduled to run.
  * Consider using __napi_schedule_irqoff() if hard irqs are masked.
  */
 void __napi_schedule(struct napi_struct *n)
 {
     unsigned long flags;
 
     local_irq_save(flags);
     ____napi_schedule(this_cpu_ptr(&softnet_data), n);
     local_irq_restore(flags);
 }
 EXPORT_SYMBOL(__napi_schedule);
 
 /**
  *  napi_schedule_prep - check if napi can be scheduled
  *  @n: napi context
  *
  * Test if NAPI routine is already running, and if not mark
  * it as running.  This is used as a condition variable to
  * insure only one NAPI poll instance runs.  We also make
  * sure there is no pending NAPI disable.
  */
 bool napi_schedule_prep(struct napi_struct *n)
 {
     unsigned long val, new;
 
     do {
         val = READ_ONCE(n->state);
         if (unlikely(val & NAPIF_STATE_DISABLE))
             return false;
         new = val | NAPIF_STATE_SCHED;
 
         /* Sets STATE_MISSED bit if STATE_SCHED was already set
          * This was suggested by Alexander Duyck, as compiler
          * emits better code than :
          * if (val & NAPIF_STATE_SCHED)
          *     new |= NAPIF_STATE_MISSED;
          */
         new |= (val & NAPIF_STATE_SCHED) / NAPIF_STATE_SCHED *
                            NAPIF_STATE_MISSED;
     } while (cmpxchg(&n->state, val, new) != val);
 
     return !(val & NAPIF_STATE_SCHED);
 }
 EXPORT_SYMBOL(napi_schedule_prep);
 
 /**
  * __napi_schedule_irqoff - schedule for receive
  * @n: entry to schedule
  *
  * Variant of __napi_schedule() assuming hard irqs are masked.
  *
  * On PREEMPT_RT enabled kernels this maps to __napi_schedule()
  * because the interrupt disabled assumption might not be true
  * due to force-threaded interrupts and spinlock substitution.
  */
 void __napi_schedule_irqoff(struct napi_struct *n)
 {
     if (!IS_ENABLED(CONFIG_PREEMPT_RT))
         ____napi_schedule(this_cpu_ptr(&softnet_data), n);
     else
         __napi_schedule(n);
 }
 EXPORT_SYMBOL(__napi_schedule_irqoff);
 
 bool napi_complete_done(struct napi_struct *n, int work_done)
 {
     unsigned long flags, val, new, timeout = 0;
     bool ret = true;
 
     /*
      * 1) Don't let napi dequeue from the cpu poll list
      *    just in case its running on a different cpu.
      * 2) If we are busy polling, do nothing here, we have
      *    the guarantee we will be called later.
      */
     if (unlikely(n->state & (NAPIF_STATE_NPSVC |
                  NAPIF_STATE_IN_BUSY_POLL)))
         return false;
 
     if (work_done) {
         if (n->gro_bitmask)
             timeout = READ_ONCE(n->dev->gro_flush_timeout);
         n->defer_hard_irqs_count = READ_ONCE(n->dev->napi_defer_hard_irqs);
     }
     if (n->defer_hard_irqs_count > 0) {
         n->defer_hard_irqs_count--;
         timeout = READ_ONCE(n->dev->gro_flush_timeout);
         if (timeout)
             ret = false;
     }
     if (n->gro_bitmask) {
         /* When the NAPI instance uses a timeout and keeps postponing
          * it, we need to bound somehow the time packets are kept in
          * the GRO layer
          */
         napi_gro_flush(n, !!timeout);
     }
 
     gro_normal_list(n);
 
     if (unlikely(!list_empty(&n->poll_list))) {
         /* If n->poll_list is not empty, we need to mask irqs */
         local_irq_save(flags);
         list_del_init(&n->poll_list);
         local_irq_restore(flags);
     }
 
     do {
         val = READ_ONCE(n->state);
 
         WARN_ON_ONCE(!(val & NAPIF_STATE_SCHED));
 
         new = val & ~(NAPIF_STATE_MISSED | NAPIF_STATE_SCHED |
                   NAPIF_STATE_SCHED_THREADED |
                   NAPIF_STATE_PREFER_BUSY_POLL);
 
         /* If STATE_MISSED was set, leave STATE_SCHED set,
          * because we will call napi->poll() one more time.
          * This C code was suggested by Alexander Duyck to help gcc.
          */
         new |= (val & NAPIF_STATE_MISSED) / NAPIF_STATE_MISSED *
                             NAPIF_STATE_SCHED;
     } while (cmpxchg(&n->state, val, new) != val);
 
     if (unlikely(val & NAPIF_STATE_MISSED)) {
         __napi_schedule(n);
         return false;
     }
 
     if (timeout)
         hrtimer_start(&n->timer, ns_to_ktime(timeout),
                   HRTIMER_MODE_REL_PINNED);
     return ret;
 }
 EXPORT_SYMBOL(napi_complete_done);
 
 /* must be called under rcu_read_lock(), as we dont take a reference */
 static struct napi_struct *napi_by_id(unsigned int napi_id)
 {
     unsigned int hash = napi_id % HASH_SIZE(napi_hash);
     struct napi_struct *napi;
 
     hlist_for_each_entry_rcu(napi, &napi_hash[hash], napi_hash_node)
         if (napi->napi_id == napi_id)
             return napi;
 
     return NULL;
 }
 
 #if defined(CONFIG_NET_RX_BUSY_POLL)
 
 static void __busy_poll_stop(struct napi_struct *napi, bool skip_schedule)
 {
     if (!skip_schedule) {
         gro_normal_list(napi);
         __napi_schedule(napi);
         return;
     }
 
     if (napi->gro_bitmask) {
         /* flush too old packets
          * If HZ < 1000, flush all packets.
          */
         napi_gro_flush(napi, HZ >= 1000);
     }
 
     gro_normal_list(napi);
     clear_bit(NAPI_STATE_SCHED, &napi->state);
 }
 
 static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock, bool prefer_busy_poll,
                u16 budget)
 {
     bool skip_schedule = false;
     unsigned long timeout;
     int rc;
 
     /* Busy polling means there is a high chance device driver hard irq
      * could not grab NAPI_STATE_SCHED, and that NAPI_STATE_MISSED was
      * set in napi_schedule_prep().
      * Since we are about to call napi->poll() once more, we can safely
      * clear NAPI_STATE_MISSED.
      *
      * Note: x86 could use a single "lock and ..." instruction
      * to perform these two clear_bit()
      */
     clear_bit(NAPI_STATE_MISSED, &napi->state);
     clear_bit(NAPI_STATE_IN_BUSY_POLL, &napi->state);
 
     local_bh_disable();
 
     if (prefer_busy_poll) {
         napi->defer_hard_irqs_count = READ_ONCE(napi->dev->napi_defer_hard_irqs);
         timeout = READ_ONCE(napi->dev->gro_flush_timeout);
         if (napi->defer_hard_irqs_count && timeout) {
             hrtimer_start(&napi->timer, ns_to_ktime(timeout), HRTIMER_MODE_REL_PINNED);
             skip_schedule = true;
         }
     }
 
     /* All we really want here is to re-enable device interrupts.
      * Ideally, a new ndo_busy_poll_stop() could avoid another round.
      */
     rc = napi->poll(napi, budget);
     /* We can't gro_normal_list() here, because napi->poll() might have
      * rearmed the napi (napi_complete_done()) in which case it could
      * already be running on another CPU.
      */
     trace_napi_poll(napi, rc, budget);
     netpoll_poll_unlock(have_poll_lock);
     if (rc == budget)
         __busy_poll_stop(napi, skip_schedule);
     local_bh_enable();
 }
 
 void napi_busy_loop(unsigned int napi_id,
             bool (*loop_end)(void *, unsigned long),
             void *loop_end_arg, bool prefer_busy_poll, u16 budget)
 {
     unsigned long start_time = loop_end ? busy_loop_current_time() : 0;
     int (*napi_poll)(struct napi_struct *napi, int budget);
     void *have_poll_lock = NULL;
     struct napi_struct *napi;
 
 restart:
     napi_poll = NULL;
 
     rcu_read_lock();
 
     napi = napi_by_id(napi_id);
     if (!napi)
         goto out;
 
     preempt_disable();
     for (;;) {
         int work = 0;
 
         local_bh_disable();
         if (!napi_poll) {
             unsigned long val = READ_ONCE(napi->state);
 
             /* If multiple threads are competing for this napi,
              * we avoid dirtying napi->state as much as we can.
              */
             if (val & (NAPIF_STATE_DISABLE | NAPIF_STATE_SCHED |
                    NAPIF_STATE_IN_BUSY_POLL)) {
                 if (prefer_busy_poll)
                     set_bit(NAPI_STATE_PREFER_BUSY_POLL, &napi->state);
                 goto count;
             }
             if (cmpxchg(&napi->state, val,
                     val | NAPIF_STATE_IN_BUSY_POLL |
                       NAPIF_STATE_SCHED) != val) {
                 if (prefer_busy_poll)
                     set_bit(NAPI_STATE_PREFER_BUSY_POLL, &napi->state);
                 goto count;
             }
             have_poll_lock = netpoll_poll_lock(napi);
             napi_poll = napi->poll;
         }
         work = napi_poll(napi, budget);
         trace_napi_poll(napi, work, budget);
         gro_normal_list(napi);
 count:
         if (work > 0)
             __NET_ADD_STATS(dev_net(napi->dev),
                     LINUX_MIB_BUSYPOLLRXPACKETS, work);
         local_bh_enable();
 
         if (!loop_end || loop_end(loop_end_arg, start_time))
             break;
 
         if (unlikely(need_resched())) {
             if (napi_poll)
                 busy_poll_stop(napi, have_poll_lock, prefer_busy_poll, budget);
             preempt_enable();
             rcu_read_unlock();
             cond_resched();
             if (loop_end(loop_end_arg, start_time))
                 return;
             goto restart;
         }
         cpu_relax();
     }
     if (napi_poll)
         busy_poll_stop(napi, have_poll_lock, prefer_busy_poll, budget);
     preempt_enable();
 out:
     rcu_read_unlock();
 }
 EXPORT_SYMBOL(napi_busy_loop);
 
 #endif /* CONFIG_NET_RX_BUSY_POLL */
 
 static void napi_hash_add(struct napi_struct *napi)
 {
     if (test_bit(NAPI_STATE_NO_BUSY_POLL, &napi->state))
         return;
 
     spin_lock(&napi_hash_lock);
 
     /* 0..NR_CPUS range is reserved for sender_cpu use */
     do {
         if (unlikely(++napi_gen_id < MIN_NAPI_ID))
             napi_gen_id = MIN_NAPI_ID;
     } while (napi_by_id(napi_gen_id));
     napi->napi_id = napi_gen_id;
 
     hlist_add_head_rcu(&napi->napi_hash_node,
                &napi_hash[napi->napi_id % HASH_SIZE(napi_hash)]);
 
     spin_unlock(&napi_hash_lock);
 }
 
 /* Warning : caller is responsible to make sure rcu grace period
  * is respected before freeing memory containing @napi
  */
 static void napi_hash_del(struct napi_struct *napi)
 {
     spin_lock(&napi_hash_lock);
 
     hlist_del_init_rcu(&napi->napi_hash_node);
 
     spin_unlock(&napi_hash_lock);
 }
 
 static enum hrtimer_restart napi_watchdog(struct hrtimer *timer)
 {
     struct napi_struct *napi;
 
     napi = container_of(timer, struct napi_struct, timer);
 
     /* Note : we use a relaxed variant of napi_schedule_prep() not setting
      * NAPI_STATE_MISSED, since we do not react to a device IRQ.
      */
     if (!napi_disable_pending(napi) &&
         !test_and_set_bit(NAPI_STATE_SCHED, &napi->state)) {
         clear_bit(NAPI_STATE_PREFER_BUSY_POLL, &napi->state);
         __napi_schedule_irqoff(napi);
     }
 
     return HRTIMER_NORESTART;
 }
 
 static void init_gro_hash(struct napi_struct *napi)
 {
     int i;
 
     for (i = 0; i < GRO_HASH_BUCKETS; i++) {
         INIT_LIST_HEAD(&napi->gro_hash[i].list);
         napi->gro_hash[i].count = 0;
     }
     napi->gro_bitmask = 0;
 }
 
 int dev_set_threaded(struct net_device *dev, bool threaded)
 {
     struct napi_struct *napi;
     int err = 0;
 
     if (dev->threaded == threaded)
         return 0;
 
     if (threaded) {
         list_for_each_entry(napi, &dev->napi_list, dev_list) {
             if (!napi->thread) {
                 err = napi_kthread_create(napi);
                 if (err) {
                     threaded = false;
                     break;
                 }
             }
         }
     }
 
     dev->threaded = threaded;
 
     /* Make sure kthread is created before THREADED bit
      * is set.
      */
     smp_mb__before_atomic();
 
     /* Setting/unsetting threaded mode on a napi might not immediately
      * take effect, if the current napi instance is actively being
      * polled. In this case, the switch between threaded mode and
      * softirq mode will happen in the next round of napi_schedule().
      * This should not cause hiccups/stalls to the live traffic.
      */
     list_for_each_entry(napi, &dev->napi_list, dev_list) {
         if (threaded)
             set_bit(NAPI_STATE_THREADED, &napi->state);
         else
             clear_bit(NAPI_STATE_THREADED, &napi->state);
     }
 
     return err;
 }
 EXPORT_SYMBOL(dev_set_threaded);
 
 /* Double check that napi_get_frags() allocates skbs with
  * skb->head being backed by slab, not a page fragment.
  * This is to make sure bug fixed in 3226b158e67c
  * ("net: avoid 32 x truesize under-estimation for tiny skbs")
  * does not accidentally come back.
  */
 static void napi_get_frags_check(struct napi_struct *napi)
 {
     struct sk_buff *skb;
 
     local_bh_disable();
     skb = napi_get_frags(napi);
     WARN_ON_ONCE(skb && skb->head_frag);
     napi_free_frags(napi);
     local_bh_enable();
 }
 
 void netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi,
                int (*poll)(struct napi_struct *, int), int weight)
 {
     if (WARN_ON(test_and_set_bit(NAPI_STATE_LISTED, &napi->state)))
         return;
 
     INIT_LIST_HEAD(&napi->poll_list);
     INIT_HLIST_NODE(&napi->napi_hash_node);
     hrtimer_init(&napi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED);
     napi->timer.function = napi_watchdog;
     init_gro_hash(napi);
     napi->skb = NULL;
     INIT_LIST_HEAD(&napi->rx_list);
     napi->rx_count = 0;
     napi->poll = poll;
     if (weight > NAPI_POLL_WEIGHT)
         netdev_err_once(dev, "%s() called with weight %d\n", __func__,
                 weight);
     napi->weight = weight;
     napi->dev = dev;
 #ifdef CONFIG_NETPOLL
     napi->poll_owner = -1;
 #endif
     set_bit(NAPI_STATE_SCHED, &napi->state);
     set_bit(NAPI_STATE_NPSVC, &napi->state);
     list_add_rcu(&napi->dev_list, &dev->napi_list);
     napi_hash_add(napi);
     napi_get_frags_check(napi);
     /* Create kthread for this napi if dev->threaded is set.
      * Clear dev->threaded if kthread creation failed so that
      * threaded mode will not be enabled in napi_enable().
      */
     if (dev->threaded && napi_kthread_create(napi))
         dev->threaded = 0;
 }
 EXPORT_SYMBOL(netif_napi_add_weight);
 
 void napi_disable(struct napi_struct *n)
 {
     unsigned long val, new;
 
     might_sleep();
     set_bit(NAPI_STATE_DISABLE, &n->state);
 
     for ( ; ; ) {
         val = READ_ONCE(n->state);
         if (val & (NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC)) {
             usleep_range(20, 200);
             continue;
         }
 
         new = val | NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC;
         new &= ~(NAPIF_STATE_THREADED | NAPIF_STATE_PREFER_BUSY_POLL);
 
         if (cmpxchg(&n->state, val, new) == val)
             break;
     }
 
     hrtimer_cancel(&n->timer);
 
     clear_bit(NAPI_STATE_DISABLE, &n->state);
 }
 EXPORT_SYMBOL(napi_disable);
 
 /**
  *  napi_enable - enable NAPI scheduling
  *  @n: NAPI context
  *
  * Resume NAPI from being scheduled on this context.
  * Must be paired with napi_disable.
  */
 void napi_enable(struct napi_struct *n)
 {
     unsigned long val, new;
 
     do {
         val = READ_ONCE(n->state);
         BUG_ON(!test_bit(NAPI_STATE_SCHED, &val));
 
         new = val & ~(NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC);
         if (n->dev->threaded && n->thread)
             new |= NAPIF_STATE_THREADED;
     } while (cmpxchg(&n->state, val, new) != val);
 }
 EXPORT_SYMBOL(napi_enable);
 
 static void flush_gro_hash(struct napi_struct *napi)
 {
     int i;
 
     for (i = 0; i < GRO_HASH_BUCKETS; i++) {
         struct sk_buff *skb, *n;
 
         list_for_each_entry_safe(skb, n, &napi->gro_hash[i].list, list)
             kfree_skb(skb);
         napi->gro_hash[i].count = 0;
     }
 }
 
 /* Must be called in process context */
 void __netif_napi_del(struct napi_struct *napi)
 {
     if (!test_and_clear_bit(NAPI_STATE_LISTED, &napi->state))
         return;
 
     napi_hash_del(napi);
     list_del_rcu(&napi->dev_list);
     napi_free_frags(napi);
 
     flush_gro_hash(napi);
     napi->gro_bitmask = 0;
 
     if (napi->thread) {
         kthread_stop(napi->thread);
         napi->thread = NULL;
     }
 }
 EXPORT_SYMBOL(__netif_napi_del);
 
 static int __napi_poll(struct napi_struct *n, bool *repoll)
 {
     int work, weight;
 
     weight = n->weight;
 
     /* This NAPI_STATE_SCHED test is for avoiding a race
      * with netpoll's poll_napi().  Only the entity which
      * obtains the lock and sees NAPI_STATE_SCHED set will
      * actually make the ->poll() call.  Therefore we avoid
      * accidentally calling ->poll() when NAPI is not scheduled.
      */
     work = 0;
     if (test_bit(NAPI_STATE_SCHED, &n->state)) {
         work = n->poll(n, weight);
         trace_napi_poll(n, work, weight);
     }
 
     if (unlikely(work > weight))
         netdev_err_once(n->dev, "NAPI poll function %pS returned %d, exceeding its budget of %d.\n",
                 n->poll, work, weight);
 
     if (likely(work < weight))
         return work;
 
     /* Drivers must not modify the NAPI state if they
      * consume the entire weight.  In such cases this code
      * still "owns" the NAPI instance and therefore can
      * move the instance around on the list at-will.
      */
     if (unlikely(napi_disable_pending(n))) {
         napi_complete(n);
         return work;
     }
 
     /* The NAPI context has more processing work, but busy-polling
      * is preferred. Exit early.
      */
     if (napi_prefer_busy_poll(n)) {
         if (napi_complete_done(n, work)) {
             /* If timeout is not set, we need to make sure
              * that the NAPI is re-scheduled.
              */
             napi_schedule(n);
         }
         return work;
     }
 
     if (n->gro_bitmask) {
         /* flush too old packets
          * If HZ < 1000, flush all packets.
          */
         napi_gro_flush(n, HZ >= 1000);
     }
 
     gro_normal_list(n);
 
     /* Some drivers may have called napi_schedule
      * prior to exhausting their budget.
      */
     if (unlikely(!list_empty(&n->poll_list))) {
         pr_warn_once("%s: Budget exhausted after napi rescheduled\n",
                  n->dev ? n->dev->name : "backlog");
         return work;
     }
 
     *repoll = true;
 
     return work;
 }
 
 static int napi_poll(struct napi_struct *n, struct list_head *repoll)
 {
     bool do_repoll = false;
     void *have;
     int work;
 
     list_del_init(&n->poll_list);
 
     have = netpoll_poll_lock(n);
 
     work = __napi_poll(n, &do_repoll);
 
     if (do_repoll)
         list_add_tail(&n->poll_list, repoll);
 
     netpoll_poll_unlock(have);
 
     return work;
 }
 
 static int napi_thread_wait(struct napi_struct *napi)
 {
     bool woken = false;
 
     set_current_state(TASK_INTERRUPTIBLE);
 
     while (!kthread_should_stop()) {
         /* Testing SCHED_THREADED bit here to make sure the current
          * kthread owns this napi and could poll on this napi.
          * Testing SCHED bit is not enough because SCHED bit might be
          * set by some other busy poll thread or by napi_disable().
          */
         if (test_bit(NAPI_STATE_SCHED_THREADED, &napi->state) || woken) {
             WARN_ON(!list_empty(&napi->poll_list));
             __set_current_state(TASK_RUNNING);
             return 0;
         }
 
         schedule();
         /* woken being true indicates this thread owns this napi. */
         woken = true;
         set_current_state(TASK_INTERRUPTIBLE);
     }
     __set_current_state(TASK_RUNNING);
 
     return -1;
 }
 
 static int napi_threaded_poll(void *data)
 {
     struct napi_struct *napi = data;
     void *have;
 
     while (!napi_thread_wait(napi)) {
         for (;;) {
             bool repoll = false;
 
             local_bh_disable();
 
             have = netpoll_poll_lock(napi);
             __napi_poll(napi, &repoll);
             netpoll_poll_unlock(have);
 
             local_bh_enable();
 
             if (!repoll)
                 break;
 
             cond_resched();
         }
     }
     return 0;
 }
 
 static void skb_defer_free_flush(struct softnet_data *sd)
 {
     struct sk_buff *skb, *next;
     unsigned long flags;
 
     /* Paired with WRITE_ONCE() in skb_attempt_defer_free() */
     if (!READ_ONCE(sd->defer_list))
         return;
 
     spin_lock_irqsave(&sd->defer_lock, flags);
     skb = sd->defer_list;
     sd->defer_list = NULL;
     sd->defer_count = 0;
     spin_unlock_irqrestore(&sd->defer_lock, flags);
 
     while (skb != NULL) {
         next = skb->next;
         napi_consume_skb(skb, 1);
         skb = next;
     }
 }
 
 static __latent_entropy void net_rx_action(struct softirq_action *h)
 {
     struct softnet_data *sd = this_cpu_ptr(&softnet_data);
     unsigned long time_limit = jiffies +
         usecs_to_jiffies(READ_ONCE(netdev_budget_usecs));
     int budget = READ_ONCE(netdev_budget);
     LIST_HEAD(list);
     LIST_HEAD(repoll);
 
     local_irq_disable();
     list_splice_init(&sd->poll_list, &list);
     local_irq_enable();
 
     for (;;) {
         struct napi_struct *n;
 
         skb_defer_free_flush(sd);
 
         if (list_empty(&list)) {
             if (!sd_has_rps_ipi_waiting(sd) && list_empty(&repoll))
                 goto end;
             break;
         }
 
         n = list_first_entry(&list, struct napi_struct, poll_list);
         budget -= napi_poll(n, &repoll);
 
         /* If softirq window is exhausted then punt.
          * Allow this to run for 2 jiffies since which will allow
          * an average latency of 1.5/HZ.
          */
         if (unlikely(budget <= 0 ||
                  time_after_eq(jiffies, time_limit))) {
             sd->time_squeeze++;
             break;
         }
     }
 
     local_irq_disable();
 
     list_splice_tail_init(&sd->poll_list, &list);
     list_splice_tail(&repoll, &list);
     list_splice(&list, &sd->poll_list);
     if (!list_empty(&sd->poll_list))
         __raise_softirq_irqoff(NET_RX_SOFTIRQ);
 
     net_rps_action_and_irq_enable(sd);
 end:;
 }
 
 struct netdev_adjacent {
     struct net_device *dev;
     netdevice_tracker dev_tracker;
 
     /* upper master flag, there can only be one master device per list */
     bool master;
 
     /* lookup ignore flag */
     bool ignore;
 
     /* counter for the number of times this device was added to us */
     u16 ref_nr;
 
     /* private field for the users */
     void *private;
 
     struct list_head list;
     struct rcu_head rcu;
 };
 
 static struct netdev_adjacent *__netdev_find_adj(struct net_device *adj_dev,
                          struct list_head *adj_list)
 {
     struct netdev_adjacent *adj;
 
     list_for_each_entry(adj, adj_list, list) {
         if (adj->dev == adj_dev)
             return adj;
     }
     return NULL;
 }
 
 static int ____netdev_has_upper_dev(struct net_device *upper_dev,
                     struct netdev_nested_priv *priv)
 {
     struct net_device *dev = (struct net_device *)priv->data;
 
     return upper_dev == dev;
 }
 
 /**
  * netdev_has_upper_dev - Check if device is linked to an upper device
  * @dev: device
  * @upper_dev: upper device to check
  *
  * Find out if a device is linked to specified upper device and return true
  * in case it is. Note that this checks only immediate upper device,
  * not through a complete stack of devices. The caller must hold the RTNL lock.
  */
 bool netdev_has_upper_dev(struct net_device *dev,
               struct net_device *upper_dev)
 {
     struct netdev_nested_priv priv = {
         .data = (void *)upper_dev,
     };
 
     ASSERT_RTNL();
 
     return netdev_walk_all_upper_dev_rcu(dev, ____netdev_has_upper_dev,
                          &priv);
 }
 EXPORT_SYMBOL(netdev_has_upper_dev);
 
 /**
  * netdev_has_upper_dev_all_rcu - Check if device is linked to an upper device
  * @dev: device
  * @upper_dev: upper device to check
  *
  * Find out if a device is linked to specified upper device and return true
  * in case it is. Note that this checks the entire upper device chain.
  * The caller must hold rcu lock.
  */
 
 bool netdev_has_upper_dev_all_rcu(struct net_device *dev,
                   struct net_device *upper_dev)
 {
     struct netdev_nested_priv priv = {
         .data = (void *)upper_dev,
     };
 
     return !!netdev_walk_all_upper_dev_rcu(dev, ____netdev_has_upper_dev,
                            &priv);
 }
 EXPORT_SYMBOL(netdev_has_upper_dev_all_rcu);
 
 /**
  * netdev_has_any_upper_dev - Check if device is linked to some device
  * @dev: device
  *
  * Find out if a device is linked to an upper device and return true in case
  * it is. The caller must hold the RTNL lock.
  */
 bool netdev_has_any_upper_dev(struct net_device *dev)
 {
     ASSERT_RTNL();
 
     return !list_empty(&dev->adj_list.upper);
 }
 EXPORT_SYMBOL(netdev_has_any_upper_dev);
 
 /**
  * netdev_master_upper_dev_get - Get master upper device
  * @dev: device
  *
  * Find a master upper device and return pointer to it or NULL in case
  * it's not there. The caller must hold the RTNL lock.
  */
 struct net_device *netdev_master_upper_dev_get(struct net_device *dev)
 {
     struct netdev_adjacent *upper;
 
     ASSERT_RTNL();
 
     if (list_empty(&dev->adj_list.upper))
         return NULL;
 
     upper = list_first_entry(&dev->adj_list.upper,
                  struct netdev_adjacent, list);
     if (likely(upper->master))
         return upper->dev;
     return NULL;
 }
 EXPORT_SYMBOL(netdev_master_upper_dev_get);
 
 static struct net_device *__netdev_master_upper_dev_get(struct net_device *dev)
 {
     struct netdev_adjacent *upper;
 
     ASSERT_RTNL();
 
     if (list_empty(&dev->adj_list.upper))
         return NULL;
 
     upper = list_first_entry(&dev->adj_list.upper,
                  struct netdev_adjacent, list);
     if (likely(upper->master) && !upper->ignore)
         return upper->dev;
     return NULL;
 }
 
 /**
  * netdev_has_any_lower_dev - Check if device is linked to some device
  * @dev: device
  *
  * Find out if a device is linked to a lower device and return true in case
  * it is. The caller must hold the RTNL lock.
  */
 static bool netdev_has_any_lower_dev(struct net_device *dev)
 {
     ASSERT_RTNL();
 
     return !list_empty(&dev->adj_list.lower);
 }
 
 void *netdev_adjacent_get_private(struct list_head *adj_list)
 {
     struct netdev_adjacent *adj;
 
     adj = list_entry(adj_list, struct netdev_adjacent, list);
 
     return adj->private;
 }
 EXPORT_SYMBOL(netdev_adjacent_get_private);
 
 /**
  * netdev_upper_get_next_dev_rcu - Get the next dev from upper list
  * @dev: device
  * @iter: list_head ** of the current position
  *
  * Gets the next device from the dev's upper list, starting from iter
  * position. The caller must hold RCU read lock.
  */
 struct net_device *netdev_upper_get_next_dev_rcu(struct net_device *dev,
                          struct list_head **iter)
 {
     struct netdev_adjacent *upper;
 
     WARN_ON_ONCE(!rcu_read_lock_held() && !lockdep_rtnl_is_held());
 
     upper = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);
 
     if (&upper->list == &dev->adj_list.upper)
         return NULL;
 
     *iter = &upper->list;
 
     return upper->dev;
 }
 EXPORT_SYMBOL(netdev_upper_get_next_dev_rcu);
 
 static struct net_device *__netdev_next_upper_dev(struct net_device *dev,
                           struct list_head **iter,
                           bool *ignore)
 {
     struct netdev_adjacent *upper;
 
     upper = list_entry((*iter)->next, struct netdev_adjacent, list);
 
     if (&upper->list == &dev->adj_list.upper)
         return NULL;
 
     *iter = &upper->list;
     *ignore = upper->ignore;
 
     return upper->dev;
 }
 
 static struct net_device *netdev_next_upper_dev_rcu(struct net_device *dev,
                             struct list_head **iter)
 {
     struct netdev_adjacent *upper;
 
     WARN_ON_ONCE(!rcu_read_lock_held() && !lockdep_rtnl_is_held());
 
     upper = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);
 
     if (&upper->list == &dev->adj_list.upper)
         return NULL;
 
     *iter = &upper->list;
 
     return upper->dev;
 }
 
 static int __netdev_walk_all_upper_dev(struct net_device *dev,
                        int (*fn)(struct net_device *dev,
                      struct netdev_nested_priv *priv),
                        struct netdev_nested_priv *priv)
 {
     struct net_device *udev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
     struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
     int ret, cur = 0;
     bool ignore;
 
     now = dev;
     iter = &dev->adj_list.upper;
 
     while (1) {
         if (now != dev) {
             ret = fn(now, priv);
             if (ret)
                 return ret;
         }
 
         next = NULL;
         while (1) {
             udev = __netdev_next_upper_dev(now, &iter, &ignore);
             if (!udev)
                 break;
             if (ignore)
                 continue;
 
             next = udev;
             niter = &udev->adj_list.upper;
             dev_stack[cur] = now;
             iter_stack[cur++] = iter;
             break;
         }
 
         if (!next) {
             if (!cur)
                 return 0;
             next = dev_stack[--cur];
             niter = iter_stack[cur];
         }
 
         now = next;
         iter = niter;
     }
 
     return 0;
 }
 
 int netdev_walk_all_upper_dev_rcu(struct net_device *dev,
                   int (*fn)(struct net_device *dev,
                         struct netdev_nested_priv *priv),
                   struct netdev_nested_priv *priv)
 {
     struct net_device *udev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
     struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
     int ret, cur = 0;
 
     now = dev;
     iter = &dev->adj_list.upper;
 
     while (1) {
         if (now != dev) {
             ret = fn(now, priv);
             if (ret)
                 return ret;
         }
 
         next = NULL;
         while (1) {
             udev = netdev_next_upper_dev_rcu(now, &iter);
             if (!udev)
                 break;
 
             next = udev;
             niter = &udev->adj_list.upper;
             dev_stack[cur] = now;
             iter_stack[cur++] = iter;
             break;
         }
 
         if (!next) {
             if (!cur)
                 return 0;
             next = dev_stack[--cur];
             niter = iter_stack[cur];
         }
 
         now = next;
         iter = niter;
     }
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(netdev_walk_all_upper_dev_rcu);
 
 static bool __netdev_has_upper_dev(struct net_device *dev,
                    struct net_device *upper_dev)
 {
     struct netdev_nested_priv priv = {
         .flags = 0,
         .data = (void *)upper_dev,
     };
 
     ASSERT_RTNL();
 
     return __netdev_walk_all_upper_dev(dev, ____netdev_has_upper_dev,
                        &priv);
 }
 
 /**
  * netdev_lower_get_next_private - Get the next ->private from the
  *                 lower neighbour list
  * @dev: device
  * @iter: list_head ** of the current position
  *
  * Gets the next netdev_adjacent->private from the dev's lower neighbour
  * list, starting from iter position. The caller must hold either hold the
  * RTNL lock or its own locking that guarantees that the neighbour lower
  * list will remain unchanged.
  */
 void *netdev_lower_get_next_private(struct net_device *dev,
                     struct list_head **iter)
 {
     struct netdev_adjacent *lower;
 
     lower = list_entry(*iter, struct netdev_adjacent, list);
 
     if (&lower->list == &dev->adj_list.lower)
         return NULL;
 
     *iter = lower->list.next;
 
     return lower->private;
 }
 EXPORT_SYMBOL(netdev_lower_get_next_private);
 
 /**
  * netdev_lower_get_next_private_rcu - Get the next ->private from the
  *                     lower neighbour list, RCU
  *                     variant
  * @dev: device
  * @iter: list_head ** of the current position
  *
  * Gets the next netdev_adjacent->private from the dev's lower neighbour
  * list, starting from iter position. The caller must hold RCU read lock.
  */
 void *netdev_lower_get_next_private_rcu(struct net_device *dev,
                     struct list_head **iter)
 {
     struct netdev_adjacent *lower;
 
     WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
 
     lower = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);
 
     if (&lower->list == &dev->adj_list.lower)
         return NULL;
 
     *iter = &lower->list;
 
     return lower->private;
 }
 EXPORT_SYMBOL(netdev_lower_get_next_private_rcu);
 
 /**
  * netdev_lower_get_next - Get the next device from the lower neighbour
  *                         list
  * @dev: device
  * @iter: list_head ** of the current position
  *
  * Gets the next netdev_adjacent from the dev's lower neighbour
  * list, starting from iter position. The caller must hold RTNL lock or
  * its own locking that guarantees that the neighbour lower
  * list will remain unchanged.
  */
 void *netdev_lower_get_next(struct net_device *dev, struct list_head **iter)
 {
     struct netdev_adjacent *lower;
 
     lower = list_entry(*iter, struct netdev_adjacent, list);
 
     if (&lower->list == &dev->adj_list.lower)
         return NULL;
 
     *iter = lower->list.next;
 
     return lower->dev;
 }
 EXPORT_SYMBOL(netdev_lower_get_next);
 
 static struct net_device *netdev_next_lower_dev(struct net_device *dev,
                         struct list_head **iter)
 {
     struct netdev_adjacent *lower;
 
     lower = list_entry((*iter)->next, struct netdev_adjacent, list);
 
     if (&lower->list == &dev->adj_list.lower)
         return NULL;
 
     *iter = &lower->list;
 
     return lower->dev;
 }
 
 static struct net_device *__netdev_next_lower_dev(struct net_device *dev,
                           struct list_head **iter,
                           bool *ignore)
 {
     struct netdev_adjacent *lower;
 
     lower = list_entry((*iter)->next, struct netdev_adjacent, list);
 
     if (&lower->list == &dev->adj_list.lower)
         return NULL;
 
     *iter = &lower->list;
     *ignore = lower->ignore;
 
     return lower->dev;
 }
 
 int netdev_walk_all_lower_dev(struct net_device *dev,
                   int (*fn)(struct net_device *dev,
                     struct netdev_nested_priv *priv),
                   struct netdev_nested_priv *priv)
 {
     struct net_device *ldev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
     struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
     int ret, cur = 0;
 
     now = dev;
     iter = &dev->adj_list.lower;
 
     while (1) {
         if (now != dev) {
             ret = fn(now, priv);
             if (ret)
                 return ret;
         }
 
         next = NULL;
         while (1) {
             ldev = netdev_next_lower_dev(now, &iter);
             if (!ldev)
                 break;
 
             next = ldev;
             niter = &ldev->adj_list.lower;
             dev_stack[cur] = now;
             iter_stack[cur++] = iter;
             break;
         }
 
         if (!next) {
             if (!cur)
                 return 0;
             next = dev_stack[--cur];
             niter = iter_stack[cur];
         }
 
         now = next;
         iter = niter;
     }
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(netdev_walk_all_lower_dev);
 
 static int __netdev_walk_all_lower_dev(struct net_device *dev,
                        int (*fn)(struct net_device *dev,
                      struct netdev_nested_priv *priv),
                        struct netdev_nested_priv *priv)
 {
     struct net_device *ldev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
     struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
     int ret, cur = 0;
     bool ignore;
 
     now = dev;
     iter = &dev->adj_list.lower;
 
     while (1) {
         if (now != dev) {
             ret = fn(now, priv);
             if (ret)
                 return ret;
         }
 
         next = NULL;
         while (1) {
             ldev = __netdev_next_lower_dev(now, &iter, &ignore);
             if (!ldev)
                 break;
             if (ignore)
                 continue;
 
             next = ldev;
             niter = &ldev->adj_list.lower;
             dev_stack[cur] = now;
             iter_stack[cur++] = iter;
             break;
         }
 
         if (!next) {
             if (!cur)
                 return 0;
             next = dev_stack[--cur];
             niter = iter_stack[cur];
         }
 
         now = next;
         iter = niter;
     }
 
     return 0;
 }
 
 struct net_device *netdev_next_lower_dev_rcu(struct net_device *dev,
                          struct list_head **iter)
 {
     struct netdev_adjacent *lower;
 
     lower = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);
     if (&lower->list == &dev->adj_list.lower)
         return NULL;
 
     *iter = &lower->list;
 
     return lower->dev;
 }
 EXPORT_SYMBOL(netdev_next_lower_dev_rcu);
 
 static u8 __netdev_upper_depth(struct net_device *dev)
 {
     struct net_device *udev;
     struct list_head *iter;
     u8 max_depth = 0;
     bool ignore;
 
     for (iter = &dev->adj_list.upper,
          udev = __netdev_next_upper_dev(dev, &iter, &ignore);
          udev;
          udev = __netdev_next_upper_dev(dev, &iter, &ignore)) {
         if (ignore)
             continue;
         if (max_depth < udev->upper_level)
             max_depth = udev->upper_level;
     }
 
     return max_depth;
 }
 
 static u8 __netdev_lower_depth(struct net_device *dev)
 {
     struct net_device *ldev;
     struct list_head *iter;
     u8 max_depth = 0;
     bool ignore;
 
     for (iter = &dev->adj_list.lower,
          ldev = __netdev_next_lower_dev(dev, &iter, &ignore);
          ldev;
          ldev = __netdev_next_lower_dev(dev, &iter, &ignore)) {
         if (ignore)
             continue;
         if (max_depth < ldev->lower_level)
             max_depth = ldev->lower_level;
     }
 
     return max_depth;
 }
 
 static int __netdev_update_upper_level(struct net_device *dev,
                        struct netdev_nested_priv *__unused)
 {
     dev->upper_level = __netdev_upper_depth(dev) + 1;
     return 0;
 }
 
 #ifdef CONFIG_LOCKDEP
 static LIST_HEAD(net_unlink_list);
 
 static void net_unlink_todo(struct net_device *dev)
 {
     if (list_empty(&dev->unlink_list))
         list_add_tail(&dev->unlink_list, &net_unlink_list);
 }
 #endif
 
 static int __netdev_update_lower_level(struct net_device *dev,
                        struct netdev_nested_priv *priv)
 {
     dev->lower_level = __netdev_lower_depth(dev) + 1;
 
 #ifdef CONFIG_LOCKDEP
     if (!priv)
         return 0;
 
     if (priv->flags & NESTED_SYNC_IMM)
         dev->nested_level = dev->lower_level - 1;
     if (priv->flags & NESTED_SYNC_TODO)
         net_unlink_todo(dev);
 #endif
     return 0;
 }
 
 int netdev_walk_all_lower_dev_rcu(struct net_device *dev,
                   int (*fn)(struct net_device *dev,
                         struct netdev_nested_priv *priv),
                   struct netdev_nested_priv *priv)
 {
     struct net_device *ldev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
     struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
     int ret, cur = 0;
 
     now = dev;
     iter = &dev->adj_list.lower;
 
     while (1) {
         if (now != dev) {
             ret = fn(now, priv);
             if (ret)
                 return ret;
         }
 
         next = NULL;
         while (1) {
             ldev = netdev_next_lower_dev_rcu(now, &iter);
             if (!ldev)
                 break;
 
             next = ldev;
             niter = &ldev->adj_list.lower;
             dev_stack[cur] = now;
             iter_stack[cur++] = iter;
             break;
         }
 
         if (!next) {
             if (!cur)
                 return 0;
             next = dev_stack[--cur];
             niter = iter_stack[cur];
         }
 
         now = next;
         iter = niter;
     }
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(netdev_walk_all_lower_dev_rcu);
 
 /**
  * netdev_lower_get_first_private_rcu - Get the first ->private from the
  *                     lower neighbour list, RCU
  *                     variant
  * @dev: device
  *
  * Gets the first netdev_adjacent->private from the dev's lower neighbour
  * list. The caller must hold RCU read lock.
  */
 void *netdev_lower_get_first_private_rcu(struct net_device *dev)
 {
     struct netdev_adjacent *lower;
 
     lower = list_first_or_null_rcu(&dev->adj_list.lower,
             struct netdev_adjacent, list);
     if (lower)
         return lower->private;
     return NULL;
 }
 EXPORT_SYMBOL(netdev_lower_get_first_private_rcu);
 
 /**
  * netdev_master_upper_dev_get_rcu - Get master upper device
  * @dev: device
  *
  * Find a master upper device and return pointer to it or NULL in case
  * it's not there. The caller must hold the RCU read lock.
  */
 struct net_device *netdev_master_upper_dev_get_rcu(struct net_device *dev)
 {
     struct netdev_adjacent *upper;
 
     upper = list_first_or_null_rcu(&dev->adj_list.upper,
                        struct netdev_adjacent, list);
     if (upper && likely(upper->master))
         return upper->dev;
     return NULL;
 }
 EXPORT_SYMBOL(netdev_master_upper_dev_get_rcu);
 
 static int netdev_adjacent_sysfs_add(struct net_device *dev,
                   struct net_device *adj_dev,
                   struct list_head *dev_list)
 {
     char linkname[IFNAMSIZ+7];
 
     sprintf(linkname, dev_list == &dev->adj_list.upper ?
         "upper_%s" : "lower_%s", adj_dev->name);
     return sysfs_create_link(&(dev->dev.kobj), &(adj_dev->dev.kobj),
                  linkname);
 }
 static void netdev_adjacent_sysfs_del(struct net_device *dev,
                    char *name,
                    struct list_head *dev_list)
 {
     char linkname[IFNAMSIZ+7];
 
     sprintf(linkname, dev_list == &dev->adj_list.upper ?
         "upper_%s" : "lower_%s", name);
     sysfs_remove_link(&(dev->dev.kobj), linkname);
 }
 
 static inline bool netdev_adjacent_is_neigh_list(struct net_device *dev,
                          struct net_device *adj_dev,
                          struct list_head *dev_list)
 {
     return (dev_list == &dev->adj_list.upper ||
         dev_list == &dev->adj_list.lower) &&
         net_eq(dev_net(dev), dev_net(adj_dev));
 }
 
 static int __netdev_adjacent_dev_insert(struct net_device *dev,
                     struct net_device *adj_dev,
                     struct list_head *dev_list,
                     void *private, bool master)
 {
     struct netdev_adjacent *adj;
     int ret;
 
     adj = __netdev_find_adj(adj_dev, dev_list);
 
     if (adj) {
         adj->ref_nr += 1;
         pr_debug("Insert adjacency: dev %s adj_dev %s adj->ref_nr %d\n",
              dev->name, adj_dev->name, adj->ref_nr);
 
         return 0;
     }
 
     adj = kmalloc(sizeof(*adj), GFP_KERNEL);
     if (!adj)
         return -ENOMEM;
 
     adj->dev = adj_dev;
     adj->master = master;
     adj->ref_nr = 1;
     adj->private = private;
     adj->ignore = false;
     netdev_hold(adj_dev, &adj->dev_tracker, GFP_KERNEL);
 
     pr_debug("Insert adjacency: dev %s adj_dev %s adj->ref_nr %d; dev_hold on %s\n",
          dev->name, adj_dev->name, adj->ref_nr, adj_dev->name);
 
     if (netdev_adjacent_is_neigh_list(dev, adj_dev, dev_list)) {
         ret = netdev_adjacent_sysfs_add(dev, adj_dev, dev_list);
         if (ret)
             goto free_adj;
     }
 
     /* Ensure that master link is always the first item in list. */
     if (master) {
         ret = sysfs_create_link(&(dev->dev.kobj),
                     &(adj_dev->dev.kobj), "master");
         if (ret)
             goto remove_symlinks;
 
         list_add_rcu(&adj->list, dev_list);
     } else {
         list_add_tail_rcu(&adj->list, dev_list);
     }
 
     return 0;
 
 remove_symlinks:
     if (netdev_adjacent_is_neigh_list(dev, adj_dev, dev_list))
         netdev_adjacent_sysfs_del(dev, adj_dev->name, dev_list);
 free_adj:
     netdev_put(adj_dev, &adj->dev_tracker);
     kfree(adj);
 
     return ret;
 }
 
 static void __netdev_adjacent_dev_remove(struct net_device *dev,
                      struct net_device *adj_dev,
                      u16 ref_nr,
                      struct list_head *dev_list)
 {
     struct netdev_adjacent *adj;
 
     pr_debug("Remove adjacency: dev %s adj_dev %s ref_nr %d\n",
          dev->name, adj_dev->name, ref_nr);
 
     adj = __netdev_find_adj(adj_dev, dev_list);
 
     if (!adj) {
         pr_err("Adjacency does not exist for device %s from %s\n",
                dev->name, adj_dev->name);
         WARN_ON(1);
         return;
     }
 
     if (adj->ref_nr > ref_nr) {
         pr_debug("adjacency: %s to %s ref_nr - %d = %d\n",
              dev->name, adj_dev->name, ref_nr,
              adj->ref_nr - ref_nr);
         adj->ref_nr -= ref_nr;
         return;
     }
 
     if (adj->master)
         sysfs_remove_link(&(dev->dev.kobj), "master");
 
     if (netdev_adjacent_is_neigh_list(dev, adj_dev, dev_list))
         netdev_adjacent_sysfs_del(dev, adj_dev->name, dev_list);
 
     list_del_rcu(&adj->list);
     pr_debug("adjacency: dev_put for %s, because link removed from %s to %s\n",
          adj_dev->name, dev->name, adj_dev->name);
     netdev_put(adj_dev, &adj->dev_tracker);
     kfree_rcu(adj, rcu);
 }
 
 static int __netdev_adjacent_dev_link_lists(struct net_device *dev,
                         struct net_device *upper_dev,
                         struct list_head *up_list,
                         struct list_head *down_list,
                         void *private, bool master)
 {
     int ret;
 
     ret = __netdev_adjacent_dev_insert(dev, upper_dev, up_list,
                        private, master);
     if (ret)
         return ret;
 
     ret = __netdev_adjacent_dev_insert(upper_dev, dev, down_list,
                        private, false);
     if (ret) {
         __netdev_adjacent_dev_remove(dev, upper_dev, 1, up_list);
         return ret;
     }
 
     return 0;
 }
 
 static void __netdev_adjacent_dev_unlink_lists(struct net_device *dev,
                            struct net_device *upper_dev,
                            u16 ref_nr,
                            struct list_head *up_list,
                            struct list_head *down_list)
 {
     __netdev_adjacent_dev_remove(dev, upper_dev, ref_nr, up_list);
     __netdev_adjacent_dev_remove(upper_dev, dev, ref_nr, down_list);
 }
 
 static int __netdev_adjacent_dev_link_neighbour(struct net_device *dev,
                         struct net_device *upper_dev,
                         void *private, bool master)
 {
     return __netdev_adjacent_dev_link_lists(dev, upper_dev,
                         &dev->adj_list.upper,
                         &upper_dev->adj_list.lower,
                         private, master);
 }
 
 static void __netdev_adjacent_dev_unlink_neighbour(struct net_device *dev,
                            struct net_device *upper_dev)
 {
     __netdev_adjacent_dev_unlink_lists(dev, upper_dev, 1,
                        &dev->adj_list.upper,
                        &upper_dev->adj_list.lower);
 }
 
 static int __netdev_upper_dev_link(struct net_device *dev,
                    struct net_device *upper_dev, bool master,
                    void *upper_priv, void *upper_info,
                    struct netdev_nested_priv *priv,
                    struct netlink_ext_ack *extack)
 {
     struct netdev_notifier_changeupper_info changeupper_info = {
         .info = {
             .dev = dev,
             .extack = extack,
         },
         .upper_dev = upper_dev,
         .master = master,
         .linking = true,
         .upper_info = upper_info,
     };
     struct net_device *master_dev;
     int ret = 0;
 
     ASSERT_RTNL();
 
     if (dev == upper_dev)
         return -EBUSY;
 
     /* To prevent loops, check if dev is not upper device to upper_dev. */
     if (__netdev_has_upper_dev(upper_dev, dev))
         return -EBUSY;
 
     if ((dev->lower_level + upper_dev->upper_level) > MAX_NEST_DEV)
         return -EMLINK;
 
     if (!master) {
         if (__netdev_has_upper_dev(dev, upper_dev))
             return -EEXIST;
     } else {
         master_dev = __netdev_master_upper_dev_get(dev);
         if (master_dev)
             return master_dev == upper_dev ? -EEXIST : -EBUSY;
     }
 
     ret = call_netdevice_notifiers_info(NETDEV_PRECHANGEUPPER,
                         &changeupper_info.info);
     ret = notifier_to_errno(ret);
     if (ret)
         return ret;
 
     ret = __netdev_adjacent_dev_link_neighbour(dev, upper_dev, upper_priv,
                            master);
     if (ret)
         return ret;
 
     ret = call_netdevice_notifiers_info(NETDEV_CHANGEUPPER,
                         &changeupper_info.info);
     ret = notifier_to_errno(ret);
     if (ret)
         goto rollback;
 
     __netdev_update_upper_level(dev, NULL);
     __netdev_walk_all_lower_dev(dev, __netdev_update_upper_level, NULL);
 
     __netdev_update_lower_level(upper_dev, priv);
     __netdev_walk_all_upper_dev(upper_dev, __netdev_update_lower_level,
                     priv);
 
     return 0;
 
 rollback:
     __netdev_adjacent_dev_unlink_neighbour(dev, upper_dev);
 
     return ret;
 }
 
 /**
  * netdev_upper_dev_link - Add a link to the upper device
  * @dev: device
  * @upper_dev: new upper device
  * @extack: netlink extended ack
  *
  * Adds a link to device which is upper to this one. The caller must hold
  * the RTNL lock. On a failure a negative errno code is returned.
  * On success the reference counts are adjusted and the function
  * returns zero.
  */
 int netdev_upper_dev_link(struct net_device *dev,
               struct net_device *upper_dev,
               struct netlink_ext_ack *extack)
 {
     struct netdev_nested_priv priv = {
         .flags = NESTED_SYNC_IMM | NESTED_SYNC_TODO,
         .data = NULL,
     };
 
     return __netdev_upper_dev_link(dev, upper_dev, false,
                        NULL, NULL, &priv, extack);
 }
 EXPORT_SYMBOL(netdev_upper_dev_link);
 
 /**
  * netdev_master_upper_dev_link - Add a master link to the upper device
  * @dev: device
  * @upper_dev: new upper device
  * @upper_priv: upper device private
  * @upper_info: upper info to be passed down via notifier
  * @extack: netlink extended ack
  *
  * Adds a link to device which is upper to this one. In this case, only
  * one master upper device can be linked, although other non-master devices
  * might be linked as well. The caller must hold the RTNL lock.
  * On a failure a negative errno code is returned. On success the reference
  * counts are adjusted and the function returns zero.
  */
 int netdev_master_upper_dev_link(struct net_device *dev,
                  struct net_device *upper_dev,
                  void *upper_priv, void *upper_info,
                  struct netlink_ext_ack *extack)
 {
     struct netdev_nested_priv priv = {
         .flags = NESTED_SYNC_IMM | NESTED_SYNC_TODO,
         .data = NULL,
     };
 
     return __netdev_upper_dev_link(dev, upper_dev, true,
                        upper_priv, upper_info, &priv, extack);
 }
 EXPORT_SYMBOL(netdev_master_upper_dev_link);
 
 static void __netdev_upper_dev_unlink(struct net_device *dev,
                       struct net_device *upper_dev,
                       struct netdev_nested_priv *priv)
 {
     struct netdev_notifier_changeupper_info changeupper_info = {
         .info = {
             .dev = dev,
         },
         .upper_dev = upper_dev,
         .linking = false,
     };
 
     ASSERT_RTNL();
 
     changeupper_info.master = netdev_master_upper_dev_get(dev) == upper_dev;
 
     call_netdevice_notifiers_info(NETDEV_PRECHANGEUPPER,
                       &changeupper_info.info);
 
     __netdev_adjacent_dev_unlink_neighbour(dev, upper_dev);
 
     call_netdevice_notifiers_info(NETDEV_CHANGEUPPER,
                       &changeupper_info.info);
 
     __netdev_update_upper_level(dev, NULL);
     __netdev_walk_all_lower_dev(dev, __netdev_update_upper_level, NULL);
 
     __netdev_update_lower_level(upper_dev, priv);
     __netdev_walk_all_upper_dev(upper_dev, __netdev_update_lower_level,
                     priv);
 }
 
 /**
  * netdev_upper_dev_unlink - Removes a link to upper device
  * @dev: device
  * @upper_dev: new upper device
  *
  * Removes a link to device which is upper to this one. The caller must hold
  * the RTNL lock.
  */
 void netdev_upper_dev_unlink(struct net_device *dev,
                  struct net_device *upper_dev)
 {
     struct netdev_nested_priv priv = {
         .flags = NESTED_SYNC_TODO,
         .data = NULL,
     };
 
     __netdev_upper_dev_unlink(dev, upper_dev, &priv);
 }
 EXPORT_SYMBOL(netdev_upper_dev_unlink);
 
 static void __netdev_adjacent_dev_set(struct net_device *upper_dev,
                       struct net_device *lower_dev,
                       bool val)
 {
     struct netdev_adjacent *adj;
 
     adj = __netdev_find_adj(lower_dev, &upper_dev->adj_list.lower);
     if (adj)
         adj->ignore = val;
 
     adj = __netdev_find_adj(upper_dev, &lower_dev->adj_list.upper);
     if (adj)
         adj->ignore = val;
 }
 
 static void netdev_adjacent_dev_disable(struct net_device *upper_dev,
                     struct net_device *lower_dev)
 {
     __netdev_adjacent_dev_set(upper_dev, lower_dev, true);
 }
 
 static void netdev_adjacent_dev_enable(struct net_device *upper_dev,
                        struct net_device *lower_dev)
 {
     __netdev_adjacent_dev_set(upper_dev, lower_dev, false);
 }
 
 int netdev_adjacent_change_prepare(struct net_device *old_dev,
                    struct net_device *new_dev,
                    struct net_device *dev,
                    struct netlink_ext_ack *extack)
 {
     struct netdev_nested_priv priv = {
         .flags = 0,
         .data = NULL,
     };
     int err;
 
     if (!new_dev)
         return 0;
 
     if (old_dev && new_dev != old_dev)
         netdev_adjacent_dev_disable(dev, old_dev);
     err = __netdev_upper_dev_link(new_dev, dev, false, NULL, NULL, &priv,
                       extack);
     if (err) {
         if (old_dev && new_dev != old_dev)
             netdev_adjacent_dev_enable(dev, old_dev);
         return err;
     }
 
     return 0;
 }
 EXPORT_SYMBOL(netdev_adjacent_change_prepare);
 
 void netdev_adjacent_change_commit(struct net_device *old_dev,
                    struct net_device *new_dev,
                    struct net_device *dev)
 {
     struct netdev_nested_priv priv = {
         .flags = NESTED_SYNC_IMM | NESTED_SYNC_TODO,
         .data = NULL,
     };
 
     if (!new_dev || !old_dev)
         return;
 
     if (new_dev == old_dev)
         return;
 
     netdev_adjacent_dev_enable(dev, old_dev);
     __netdev_upper_dev_unlink(old_dev, dev, &priv);
 }
 EXPORT_SYMBOL(netdev_adjacent_change_commit);
 
 void netdev_adjacent_change_abort(struct net_device *old_dev,
                   struct net_device *new_dev,
                   struct net_device *dev)
 {
     struct netdev_nested_priv priv = {
         .flags = 0,
         .data = NULL,
     };
 
     if (!new_dev)
         return;
 
     if (old_dev && new_dev != old_dev)
         netdev_adjacent_dev_enable(dev, old_dev);
 
     __netdev_upper_dev_unlink(new_dev, dev, &priv);
 }
 EXPORT_SYMBOL(netdev_adjacent_change_abort);
 
 /**
  * netdev_bonding_info_change - Dispatch event about slave change
  * @dev: device
  * @bonding_info: info to dispatch
  *
  * Send NETDEV_BONDING_INFO to netdev notifiers with info.
  * The caller must hold the RTNL lock.
  */
 void netdev_bonding_info_change(struct net_device *dev,
                 struct netdev_bonding_info *bonding_info)
 {
     struct netdev_notifier_bonding_info info = {
         .info.dev = dev,
     };
 
     memcpy(&info.bonding_info, bonding_info,
            sizeof(struct netdev_bonding_info));
     call_netdevice_notifiers_info(NETDEV_BONDING_INFO,
                       &info.info);
 }
 EXPORT_SYMBOL(netdev_bonding_info_change);
 
 static int netdev_offload_xstats_enable_l3(struct net_device *dev,
                        struct netlink_ext_ack *extack)
 {
     struct netdev_notifier_offload_xstats_info info = {
         .info.dev = dev,
         .info.extack = extack,
         .type = NETDEV_OFFLOAD_XSTATS_TYPE_L3,
     };
     int err;
     int rc;
 
     dev->offload_xstats_l3 = kzalloc(sizeof(*dev->offload_xstats_l3),
                      GFP_KERNEL);
     if (!dev->offload_xstats_l3)
         return -ENOMEM;
 
     rc = call_netdevice_notifiers_info_robust(NETDEV_OFFLOAD_XSTATS_ENABLE,
                           NETDEV_OFFLOAD_XSTATS_DISABLE,
                           &info.info);
     err = notifier_to_errno(rc);
     if (err)
         goto free_stats;
 
     return 0;
 
 free_stats:
     kfree(dev->offload_xstats_l3);
     dev->offload_xstats_l3 = NULL;
     return err;
 }
 
 int netdev_offload_xstats_enable(struct net_device *dev,
                  enum netdev_offload_xstats_type type,
                  struct netlink_ext_ack *extack)
 {
     ASSERT_RTNL();
 
     if (netdev_offload_xstats_enabled(dev, type))
         return -EALREADY;
 
     switch (type) {
     case NETDEV_OFFLOAD_XSTATS_TYPE_L3:
         return netdev_offload_xstats_enable_l3(dev, extack);
     }
 
     WARN_ON(1);
     return -EINVAL;
 }
 EXPORT_SYMBOL(netdev_offload_xstats_enable);
 
 static void netdev_offload_xstats_disable_l3(struct net_device *dev)
 {
     struct netdev_notifier_offload_xstats_info info = {
         .info.dev = dev,
         .type = NETDEV_OFFLOAD_XSTATS_TYPE_L3,
     };
 
     call_netdevice_notifiers_info(NETDEV_OFFLOAD_XSTATS_DISABLE,
                       &info.info);
     kfree(dev->offload_xstats_l3);
     dev->offload_xstats_l3 = NULL;
 }
 
 int netdev_offload_xstats_disable(struct net_device *dev,
                   enum netdev_offload_xstats_type type)
 {
     ASSERT_RTNL();
 
     if (!netdev_offload_xstats_enabled(dev, type))
         return -EALREADY;
 
     switch (type) {
     case NETDEV_OFFLOAD_XSTATS_TYPE_L3:
         netdev_offload_xstats_disable_l3(dev);
         return 0;
     }
 
     WARN_ON(1);
     return -EINVAL;
 }
 EXPORT_SYMBOL(netdev_offload_xstats_disable);
 
 static void netdev_offload_xstats_disable_all(struct net_device *dev)
 {
     netdev_offload_xstats_disable(dev, NETDEV_OFFLOAD_XSTATS_TYPE_L3);
 }
 
 static struct rtnl_hw_stats64 *
 netdev_offload_xstats_get_ptr(const struct net_device *dev,
                   enum netdev_offload_xstats_type type)
 {
     switch (type) {
     case NETDEV_OFFLOAD_XSTATS_TYPE_L3:
         return dev->offload_xstats_l3;
     }
 
     WARN_ON(1);
     return NULL;
 }
 
 bool netdev_offload_xstats_enabled(const struct net_device *dev,
                    enum netdev_offload_xstats_type type)
 {
     ASSERT_RTNL();
 
     return netdev_offload_xstats_get_ptr(dev, type);
 }
 EXPORT_SYMBOL(netdev_offload_xstats_enabled);
 
 struct netdev_notifier_offload_xstats_ru {
     bool used;
 };
 
 struct netdev_notifier_offload_xstats_rd {
     struct rtnl_hw_stats64 stats;
     bool used;
 };
 
 static void netdev_hw_stats64_add(struct rtnl_hw_stats64 *dest,
                   const struct rtnl_hw_stats64 *src)
 {
     dest->rx_packets      += src->rx_packets;
     dest->tx_packets      += src->tx_packets;
     dest->rx_bytes        += src->rx_bytes;
     dest->tx_bytes        += src->tx_bytes;
     dest->rx_errors       += src->rx_errors;
     dest->tx_errors       += src->tx_errors;
     dest->rx_dropped      += src->rx_dropped;
     dest->tx_dropped      += src->tx_dropped;
     dest->multicast       += src->multicast;
 }
 
 static int netdev_offload_xstats_get_used(struct net_device *dev,
                       enum netdev_offload_xstats_type type,
                       bool *p_used,
                       struct netlink_ext_ack *extack)
 {
     struct netdev_notifier_offload_xstats_ru report_used = {};
     struct netdev_notifier_offload_xstats_info info = {
         .info.dev = dev,
         .info.extack = extack,
         .type = type,
         .report_used = &report_used,
     };
     int rc;
 
     WARN_ON(!netdev_offload_xstats_enabled(dev, type));
     rc = call_netdevice_notifiers_info(NETDEV_OFFLOAD_XSTATS_REPORT_USED,
                        &info.info);
     *p_used = report_used.used;
     return notifier_to_errno(rc);
 }
 
 static int netdev_offload_xstats_get_stats(struct net_device *dev,
                        enum netdev_offload_xstats_type type,
                        struct rtnl_hw_stats64 *p_stats,
                        bool *p_used,
                        struct netlink_ext_ack *extack)
 {
     struct netdev_notifier_offload_xstats_rd report_delta = {};
     struct netdev_notifier_offload_xstats_info info = {
         .info.dev = dev,
         .info.extack = extack,
         .type = type,
         .report_delta = &report_delta,
     };
     struct rtnl_hw_stats64 *stats;
     int rc;
 
     stats = netdev_offload_xstats_get_ptr(dev, type);
     if (WARN_ON(!stats))
         return -EINVAL;
 
     rc = call_netdevice_notifiers_info(NETDEV_OFFLOAD_XSTATS_REPORT_DELTA,
                        &info.info);
 
     /* Cache whatever we got, even if there was an error, otherwise the
      * successful stats retrievals would get lost.
      */
     netdev_hw_stats64_add(stats, &report_delta.stats);
 
     if (p_stats)
         *p_stats = *stats;
     *p_used = report_delta.used;
 
     return notifier_to_errno(rc);
 }
 
 int netdev_offload_xstats_get(struct net_device *dev,
                   enum netdev_offload_xstats_type type,
                   struct rtnl_hw_stats64 *p_stats, bool *p_used,
                   struct netlink_ext_ack *extack)
 {
     ASSERT_RTNL();
 
     if (p_stats)
         return netdev_offload_xstats_get_stats(dev, type, p_stats,
                                p_used, extack);
     else
         return netdev_offload_xstats_get_used(dev, type, p_used,
                               extack);
 }
 EXPORT_SYMBOL(netdev_offload_xstats_get);
 
 void
 netdev_offload_xstats_report_delta(struct netdev_notifier_offload_xstats_rd *report_delta,
                    const struct rtnl_hw_stats64 *stats)
 {
     report_delta->used = true;
     netdev_hw_stats64_add(&report_delta->stats, stats);
 }
 EXPORT_SYMBOL(netdev_offload_xstats_report_delta);
 
 void
 netdev_offload_xstats_report_used(struct netdev_notifier_offload_xstats_ru *report_used)
 {
     report_used->used = true;
 }
 EXPORT_SYMBOL(netdev_offload_xstats_report_used);
 
 void netdev_offload_xstats_push_delta(struct net_device *dev,
                       enum netdev_offload_xstats_type type,
                       const struct rtnl_hw_stats64 *p_stats)
 {
     struct rtnl_hw_stats64 *stats;
 
     ASSERT_RTNL();
 
     stats = netdev_offload_xstats_get_ptr(dev, type);
     if (WARN_ON(!stats))
         return;
 
     netdev_hw_stats64_add(stats, p_stats);
 }
 EXPORT_SYMBOL(netdev_offload_xstats_push_delta);
 
 /**
  * netdev_get_xmit_slave - Get the xmit slave of master device
  * @dev: device
  * @skb: The packet
  * @all_slaves: assume all the slaves are active
  *
  * The reference counters are not incremented so the caller must be
  * careful with locks. The caller must hold RCU lock.
  * %NULL is returned if no slave is found.
  */
 
 struct net_device *netdev_get_xmit_slave(struct net_device *dev,
                      struct sk_buff *skb,
                      bool all_slaves)
 {
     const struct net_device_ops *ops = dev->netdev_ops;
 
     if (!ops->ndo_get_xmit_slave)
         return NULL;
     return ops->ndo_get_xmit_slave(dev, skb, all_slaves);
 }
 EXPORT_SYMBOL(netdev_get_xmit_slave);
 
 static struct net_device *netdev_sk_get_lower_dev(struct net_device *dev,
                           struct sock *sk)
 {
     const struct net_device_ops *ops = dev->netdev_ops;
 
     if (!ops->ndo_sk_get_lower_dev)
         return NULL;
     return ops->ndo_sk_get_lower_dev(dev, sk);
 }
 
 /**
  * netdev_sk_get_lowest_dev - Get the lowest device in chain given device and socket
  * @dev: device
  * @sk: the socket
  *
  * %NULL is returned if no lower device is found.
  */
 
 struct net_device *netdev_sk_get_lowest_dev(struct net_device *dev,
                         struct sock *sk)
 {
     struct net_device *lower;
 
     lower = netdev_sk_get_lower_dev(dev, sk);
     while (lower) {
         dev = lower;
         lower = netdev_sk_get_lower_dev(dev, sk);
     }
 
     return dev;
 }
 EXPORT_SYMBOL(netdev_sk_get_lowest_dev);
 
 static void netdev_adjacent_add_links(struct net_device *dev)
 {
     struct netdev_adjacent *iter;
 
     struct net *net = dev_net(dev);
 
     list_for_each_entry(iter, &dev->adj_list.upper, list) {
         if (!net_eq(net, dev_net(iter->dev)))
             continue;
         netdev_adjacent_sysfs_add(iter->dev, dev,
                       &iter->dev->adj_list.lower);
         netdev_adjacent_sysfs_add(dev, iter->dev,
                       &dev->adj_list.upper);
     }
 
     list_for_each_entry(iter, &dev->adj_list.lower, list) {
         if (!net_eq(net, dev_net(iter->dev)))
             continue;
         netdev_adjacent_sysfs_add(iter->dev, dev,
                       &iter->dev->adj_list.upper);
         netdev_adjacent_sysfs_add(dev, iter->dev,
                       &dev->adj_list.lower);
     }
 }
 
 static void netdev_adjacent_del_links(struct net_device *dev)
 {
     struct netdev_adjacent *iter;
 
     struct net *net = dev_net(dev);
 
     list_for_each_entry(iter, &dev->adj_list.upper, list) {
         if (!net_eq(net, dev_net(iter->dev)))
             continue;
         netdev_adjacent_sysfs_del(iter->dev, dev->name,
                       &iter->dev->adj_list.lower);
         netdev_adjacent_sysfs_del(dev, iter->dev->name,
                       &dev->adj_list.upper);
     }
 
     list_for_each_entry(iter, &dev->adj_list.lower, list) {
         if (!net_eq(net, dev_net(iter->dev)))
             continue;
         netdev_adjacent_sysfs_del(iter->dev, dev->name,
                       &iter->dev->adj_list.upper);
         netdev_adjacent_sysfs_del(dev, iter->dev->name,
                       &dev->adj_list.lower);
     }
 }
 
 void netdev_adjacent_rename_links(struct net_device *dev, char *oldname)
 {
     struct netdev_adjacent *iter;
 
     struct net *net = dev_net(dev);
 
     list_for_each_entry(iter, &dev->adj_list.upper, list) {
         if (!net_eq(net, dev_net(iter->dev)))
             continue;
         netdev_adjacent_sysfs_del(iter->dev, oldname,
                       &iter->dev->adj_list.lower);
         netdev_adjacent_sysfs_add(iter->dev, dev,
                       &iter->dev->adj_list.lower);
     }
 
     list_for_each_entry(iter, &dev->adj_list.lower, list) {
         if (!net_eq(net, dev_net(iter->dev)))
             continue;
         netdev_adjacent_sysfs_del(iter->dev, oldname,
                       &iter->dev->adj_list.upper);
         netdev_adjacent_sysfs_add(iter->dev, dev,
                       &iter->dev->adj_list.upper);
     }
 }
 
 void *netdev_lower_dev_get_private(struct net_device *dev,
                    struct net_device *lower_dev)
 {
     struct netdev_adjacent *lower;
 
     if (!lower_dev)
         return NULL;
     lower = __netdev_find_adj(lower_dev, &dev->adj_list.lower);
     if (!lower)
         return NULL;
 
     return lower->private;
 }
 EXPORT_SYMBOL(netdev_lower_dev_get_private);
 
 
 /**
  * netdev_lower_state_changed - Dispatch event about lower device state change
  * @lower_dev: device
  * @lower_state_info: state to dispatch
  *
  * Send NETDEV_CHANGELOWERSTATE to netdev notifiers with info.
  * The caller must hold the RTNL lock.
  */
 void netdev_lower_state_changed(struct net_device *lower_dev,
                 void *lower_state_info)
 {
     struct netdev_notifier_changelowerstate_info changelowerstate_info = {
         .info.dev = lower_dev,
     };
 
     ASSERT_RTNL();
     changelowerstate_info.lower_state_info = lower_state_info;
     call_netdevice_notifiers_info(NETDEV_CHANGELOWERSTATE,
                       &changelowerstate_info.info);
 }
 EXPORT_SYMBOL(netdev_lower_state_changed);
 
 static void dev_change_rx_flags(struct net_device *dev, int flags)
 {
     const struct net_device_ops *ops = dev->netdev_ops;
 
     if (ops->ndo_change_rx_flags)
         ops->ndo_change_rx_flags(dev, flags);
 }
 
 static int __dev_set_promiscuity(struct net_device *dev, int inc, bool notify)
 {
     unsigned int old_flags = dev->flags;
     kuid_t uid;
     kgid_t gid;
 
     ASSERT_RTNL();
 
     dev->flags |= IFF_PROMISC;
     dev->promiscuity += inc;
     if (dev->promiscuity == 0) {
         /*
          * Avoid overflow.
          * If inc causes overflow, untouch promisc and return error.
          */
         if (inc < 0)
             dev->flags &= ~IFF_PROMISC;
         else {
             dev->promiscuity -= inc;
             netdev_warn(dev, "promiscuity touches roof, set promiscuity failed. promiscuity feature of device might be broken.\n");
             return -EOVERFLOW;
         }
     }
     if (dev->flags != old_flags) {
         pr_info("device %s %s promiscuous mode\n",
             dev->name,
             dev->flags & IFF_PROMISC ? "entered" : "left");
         if (audit_enabled) {
             current_uid_gid(&uid, &gid);
             audit_log(audit_context(), GFP_ATOMIC,
                   AUDIT_ANOM_PROMISCUOUS,
                   "dev=%s prom=%d old_prom=%d auid=%u uid=%u gid=%u ses=%u",
                   dev->name, (dev->flags & IFF_PROMISC),
                   (old_flags & IFF_PROMISC),
                   from_kuid(&init_user_ns, audit_get_loginuid(current)),
                   from_kuid(&init_user_ns, uid),
                   from_kgid(&init_user_ns, gid),
                   audit_get_sessionid(current));
         }
 
         dev_change_rx_flags(dev, IFF_PROMISC);
     }
     if (notify)
         __dev_notify_flags(dev, old_flags, IFF_PROMISC);
     return 0;
 }
 
 /**
  *  dev_set_promiscuity - update promiscuity count on a device
  *  @dev: device
  *  @inc: modifier
  *
  *  Add or remove promiscuity from a device. While the count in the device
  *  remains above zero the interface remains promiscuous. Once it hits zero
  *  the device reverts back to normal filtering operation. A negative inc
  *  value is used to drop promiscuity on the device.
  *  Return 0 if successful or a negative errno code on error.
  */
 int dev_set_promiscuity(struct net_device *dev, int inc)
 {
     unsigned int old_flags = dev->flags;
     int err;
 
     err = __dev_set_promiscuity(dev, inc, true);
     if (err < 0)
         return err;
     if (dev->flags != old_flags)
         dev_set_rx_mode(dev);
     return err;
 }
 EXPORT_SYMBOL(dev_set_promiscuity);
 
 static int __dev_set_allmulti(struct net_device *dev, int inc, bool notify)
 {
     unsigned int old_flags = dev->flags, old_gflags = dev->gflags;
 
     ASSERT_RTNL();
 
     dev->flags |= IFF_ALLMULTI;
     dev->allmulti += inc;
     if (dev->allmulti == 0) {
         /*
          * Avoid overflow.
          * If inc causes overflow, untouch allmulti and return error.
          */
         if (inc < 0)
             dev->flags &= ~IFF_ALLMULTI;
         else {
             dev->allmulti -= inc;
             netdev_warn(dev, "allmulti touches roof, set allmulti failed. allmulti feature of device might be broken.\n");
             return -EOVERFLOW;
         }
     }
     if (dev->flags ^ old_flags) {
         dev_change_rx_flags(dev, IFF_ALLMULTI);
         dev_set_rx_mode(dev);
         if (notify)
             __dev_notify_flags(dev, old_flags,
                        dev->gflags ^ old_gflags);
     }
     return 0;
 }
 
 /**
  *  dev_set_allmulti    - update allmulti count on a device
  *  @dev: device
  *  @inc: modifier
  *
  *  Add or remove reception of all multicast frames to a device. While the
  *  count in the device remains above zero the interface remains listening
  *  to all interfaces. Once it hits zero the device reverts back to normal
  *  filtering operation. A negative @inc value is used to drop the counter
  *  when releasing a resource needing all multicasts.
  *  Return 0 if successful or a negative errno code on error.
  */
 
 int dev_set_allmulti(struct net_device *dev, int inc)
 {
     return __dev_set_allmulti(dev, inc, true);
 }
 EXPORT_SYMBOL(dev_set_allmulti);
 
 /*
  *  Upload unicast and multicast address lists to device and
  *  configure RX filtering. When the device doesn't support unicast
  *  filtering it is put in promiscuous mode while unicast addresses
  *  are present.
  */
 void __dev_set_rx_mode(struct net_device *dev)
 {
     const struct net_device_ops *ops = dev->netdev_ops;
 
     /* dev_open will call this function so the list will stay sane. */
     if (!(dev->flags&IFF_UP))
         return;
 
     if (!netif_device_present(dev))
         return;
 
     if (!(dev->priv_flags & IFF_UNICAST_FLT)) {
         /* Unicast addresses changes may only happen under the rtnl,
          * therefore calling __dev_set_promiscuity here is safe.
          */
         if (!netdev_uc_empty(dev) && !dev->uc_promisc) {
             __dev_set_promiscuity(dev, 1, false);
             dev->uc_promisc = true;
         } else if (netdev_uc_empty(dev) && dev->uc_promisc) {
             __dev_set_promiscuity(dev, -1, false);
             dev->uc_promisc = false;
         }
     }
 
     if (ops->ndo_set_rx_mode)
         ops->ndo_set_rx_mode(dev);
 }
 
 void dev_set_rx_mode(struct net_device *dev)
 {
     netif_addr_lock_bh(dev);
     __dev_set_rx_mode(dev);
     netif_addr_unlock_bh(dev);
 }
 
 /**
  *  dev_get_flags - get flags reported to userspace
  *  @dev: device
  *
  *  Get the combination of flag bits exported through APIs to userspace.
  */
 unsigned int dev_get_flags(const struct net_device *dev)
 {
     unsigned int flags;
 
     flags = (dev->flags & ~(IFF_PROMISC |
                 IFF_ALLMULTI |
                 IFF_RUNNING |
                 IFF_LOWER_UP |
                 IFF_DORMANT)) |
         (dev->gflags & (IFF_PROMISC |
                 IFF_ALLMULTI));
 
     if (netif_running(dev)) {
         if (netif_oper_up(dev))
             flags |= IFF_RUNNING;
         if (netif_carrier_ok(dev))
             flags |= IFF_LOWER_UP;
         if (netif_dormant(dev))
             flags |= IFF_DORMANT;
     }
 
     return flags;
 }
 EXPORT_SYMBOL(dev_get_flags);
 
 int __dev_change_flags(struct net_device *dev, unsigned int flags,
                struct netlink_ext_ack *extack)
 {
     unsigned int old_flags = dev->flags;
     int ret;
 
     ASSERT_RTNL();
 
     /*
      *  Set the flags on our device.
      */
 
     dev->flags = (flags & (IFF_DEBUG | IFF_NOTRAILERS | IFF_NOARP |
                    IFF_DYNAMIC | IFF_MULTICAST | IFF_PORTSEL |
                    IFF_AUTOMEDIA)) |
              (dev->flags & (IFF_UP | IFF_VOLATILE | IFF_PROMISC |
                     IFF_ALLMULTI));
 
     /*
      *  Load in the correct multicast list now the flags have changed.
      */
 
     if ((old_flags ^ flags) & IFF_MULTICAST)
         dev_change_rx_flags(dev, IFF_MULTICAST);
 
     dev_set_rx_mode(dev);
 
     /*
      *  Have we downed the interface. We handle IFF_UP ourselves
      *  according to user attempts to set it, rather than blindly
      *  setting it.
      */
 
     ret = 0;
     if ((old_flags ^ flags) & IFF_UP) {
         if (old_flags & IFF_UP)
             __dev_close(dev);
         else
             ret = __dev_open(dev, extack);
     }
 
     if ((flags ^ dev->gflags) & IFF_PROMISC) {
         int inc = (flags & IFF_PROMISC) ? 1 : -1;
         unsigned int old_flags = dev->flags;
 
         dev->gflags ^= IFF_PROMISC;
 
         if (__dev_set_promiscuity(dev, inc, false) >= 0)
             if (dev->flags != old_flags)
                 dev_set_rx_mode(dev);
     }
 
     /* NOTE: order of synchronization of IFF_PROMISC and IFF_ALLMULTI
      * is important. Some (broken) drivers set IFF_PROMISC, when
      * IFF_ALLMULTI is requested not asking us and not reporting.
      */
     if ((flags ^ dev->gflags) & IFF_ALLMULTI) {
         int inc = (flags & IFF_ALLMULTI) ? 1 : -1;
 
         dev->gflags ^= IFF_ALLMULTI;
         __dev_set_allmulti(dev, inc, false);
     }
 
     return ret;
 }
 
 void __dev_notify_flags(struct net_device *dev, unsigned int old_flags,
             unsigned int gchanges)
 {
     unsigned int changes = dev->flags ^ old_flags;
 
     if (gchanges)
         rtmsg_ifinfo(RTM_NEWLINK, dev, gchanges, GFP_ATOMIC);
 
     if (changes & IFF_UP) {
         if (dev->flags & IFF_UP)
             call_netdevice_notifiers(NETDEV_UP, dev);
         else
             call_netdevice_notifiers(NETDEV_DOWN, dev);
     }
 
     if (dev->flags & IFF_UP &&
         (changes & ~(IFF_UP | IFF_PROMISC | IFF_ALLMULTI | IFF_VOLATILE))) {
         struct netdev_notifier_change_info change_info = {
             .info = {
                 .dev = dev,
             },
             .flags_changed = changes,
         };
 
         call_netdevice_notifiers_info(NETDEV_CHANGE, &change_info.info);
     }
 }
 
 /**
  *  dev_change_flags - change device settings
  *  @dev: device
  *  @flags: device state flags
  *  @extack: netlink extended ack
  *
  *  Change settings on device based state flags. The flags are
  *  in the userspace exported format.
  */
 int dev_change_flags(struct net_device *dev, unsigned int flags,
              struct netlink_ext_ack *extack)
 {
     int ret;
     unsigned int changes, old_flags = dev->flags, old_gflags = dev->gflags;
 
     ret = __dev_change_flags(dev, flags, extack);
     if (ret < 0)
         return ret;
 
     changes = (old_flags ^ dev->flags) | (old_gflags ^ dev->gflags);
     __dev_notify_flags(dev, old_flags, changes);
     return ret;
 }
 EXPORT_SYMBOL(dev_change_flags);
 
 int __dev_set_mtu(struct net_device *dev, int new_mtu)
 {
     const struct net_device_ops *ops = dev->netdev_ops;
 
     if (ops->ndo_change_mtu)
         return ops->ndo_change_mtu(dev, new_mtu);
 
     /* Pairs with all the lockless reads of dev->mtu in the stack */
     WRITE_ONCE(dev->mtu, new_mtu);
     return 0;
 }
 EXPORT_SYMBOL(__dev_set_mtu);
 
 int dev_validate_mtu(struct net_device *dev, int new_mtu,
              struct netlink_ext_ack *extack)
 {
     /* MTU must be positive, and in range */
     if (new_mtu < 0 || new_mtu < dev->min_mtu) {
         NL_SET_ERR_MSG(extack, "mtu less than device minimum");
         return -EINVAL;
     }
 
     if (dev->max_mtu > 0 && new_mtu > dev->max_mtu) {
         NL_SET_ERR_MSG(extack, "mtu greater than device maximum");
         return -EINVAL;
     }
     return 0;
 }
 
 /**
  *  dev_set_mtu_ext - Change maximum transfer unit
  *  @dev: device
  *  @new_mtu: new transfer unit
  *  @extack: netlink extended ack
  *
  *  Change the maximum transfer size of the network device.
  */
 int dev_set_mtu_ext(struct net_device *dev, int new_mtu,
             struct netlink_ext_ack *extack)
 {
     int err, orig_mtu;
 
     if (new_mtu == dev->mtu)
         return 0;
 
     err = dev_validate_mtu(dev, new_mtu, extack);
     if (err)
         return err;
 
     if (!netif_device_present(dev))
         return -ENODEV;
 
     err = call_netdevice_notifiers(NETDEV_PRECHANGEMTU, dev);
     err = notifier_to_errno(err);
     if (err)
         return err;
 
     orig_mtu = dev->mtu;
     err = __dev_set_mtu(dev, new_mtu);
 
     if (!err) {
         err = call_netdevice_notifiers_mtu(NETDEV_CHANGEMTU, dev,
                            orig_mtu);
         err = notifier_to_errno(err);
         if (err) {
             /* setting mtu back and notifying everyone again,
              * so that they have a chance to revert changes.
              */
             __dev_set_mtu(dev, orig_mtu);
             call_netdevice_notifiers_mtu(NETDEV_CHANGEMTU, dev,
                              new_mtu);
         }
     }
     return err;
 }
 
 int dev_set_mtu(struct net_device *dev, int new_mtu)
 {
     struct netlink_ext_ack extack;
     int err;
 
     memset(&extack, 0, sizeof(extack));
     err = dev_set_mtu_ext(dev, new_mtu, &extack);
     if (err && extack._msg)
         net_err_ratelimited("%s: %s\n", dev->name, extack._msg);
     return err;
 }
 EXPORT_SYMBOL(dev_set_mtu);
 
 /**
  *  dev_change_tx_queue_len - Change TX queue length of a netdevice
  *  @dev: device
  *  @new_len: new tx queue length
  */
 int dev_change_tx_queue_len(struct net_device *dev, unsigned long new_len)
 {
     unsigned int orig_len = dev->tx_queue_len;
     int res;
 
     if (new_len != (unsigned int)new_len)
         return -ERANGE;
 
     if (new_len != orig_len) {
         dev->tx_queue_len = new_len;
         res = call_netdevice_notifiers(NETDEV_CHANGE_TX_QUEUE_LEN, dev);
         res = notifier_to_errno(res);
         if (res)
             goto err_rollback;
         res = dev_qdisc_change_tx_queue_len(dev);
         if (res)
             goto err_rollback;
     }
 
     return 0;
 
 err_rollback:
     netdev_err(dev, "refused to change device tx_queue_len\n");
     dev->tx_queue_len = orig_len;
     return res;
 }
 
 /**
  *  dev_set_group - Change group this device belongs to
  *  @dev: device
  *  @new_group: group this device should belong to
  */
 void dev_set_group(struct net_device *dev, int new_group)
 {
     dev->group = new_group;
 }
 
 /**
  *  dev_pre_changeaddr_notify - Call NETDEV_PRE_CHANGEADDR.
  *  @dev: device
  *  @addr: new address
  *  @extack: netlink extended ack
  */
 int dev_pre_changeaddr_notify(struct net_device *dev, const char *addr,
                   struct netlink_ext_ack *extack)
 {
     struct netdev_notifier_pre_changeaddr_info info = {
         .info.dev = dev,
         .info.extack = extack,
         .dev_addr = addr,
     };
     int rc;
 
     rc = call_netdevice_notifiers_info(NETDEV_PRE_CHANGEADDR, &info.info);
     return notifier_to_errno(rc);
 }
 EXPORT_SYMBOL(dev_pre_changeaddr_notify);
 
 /**
  *  dev_set_mac_address - Change Media Access Control Address
  *  @dev: device
  *  @sa: new address
  *  @extack: netlink extended ack
  *
  *  Change the hardware (MAC) address of the device
  */
 int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa,
             struct netlink_ext_ack *extack)
 {
     const struct net_device_ops *ops = dev->netdev_ops;
     int err;
 
     if (!ops->ndo_set_mac_address)
         return -EOPNOTSUPP;
     if (sa->sa_family != dev->type)
         return -EINVAL;
     if (!netif_device_present(dev))
         return -ENODEV;
     err = dev_pre_changeaddr_notify(dev, sa->sa_data, extack);
     if (err)
         return err;
     err = ops->ndo_set_mac_address(dev, sa);
     if (err)
         return err;
     dev->addr_assign_type = NET_ADDR_SET;
     call_netdevice_notifiers(NETDEV_CHANGEADDR, dev);
     add_device_randomness(dev->dev_addr, dev->addr_len);
     return 0;
 }
 EXPORT_SYMBOL(dev_set_mac_address);
 
 static DECLARE_RWSEM(dev_addr_sem);
 
 int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,
                  struct netlink_ext_ack *extack)
 {
     int ret;
 
     down_write(&dev_addr_sem);
     ret = dev_set_mac_address(dev, sa, extack);
     up_write(&dev_addr_sem);
     return ret;
 }
 EXPORT_SYMBOL(dev_set_mac_address_user);
 
 int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name)
 {
     size_t size = sizeof(sa->sa_data);
     struct net_device *dev;
     int ret = 0;
 
     down_read(&dev_addr_sem);
     rcu_read_lock();
 
     dev = dev_get_by_name_rcu(net, dev_name);
     if (!dev) {
         ret = -ENODEV;
         goto unlock;
     }
     if (!dev->addr_len)
         memset(sa->sa_data, 0, size);
     else
         memcpy(sa->sa_data, dev->dev_addr,
                min_t(size_t, size, dev->addr_len));
     sa->sa_family = dev->type;
 
 unlock:
     rcu_read_unlock();
     up_read(&dev_addr_sem);
     return ret;
 }
 EXPORT_SYMBOL(dev_get_mac_address);
 
 /**
  *  dev_change_carrier - Change device carrier
  *  @dev: device
  *  @new_carrier: new value
  *
  *  Change device carrier
  */
 int dev_change_carrier(struct net_device *dev, bool new_carrier)
 {
     const struct net_device_ops *ops = dev->netdev_ops;
 
     if (!ops->ndo_change_carrier)
         return -EOPNOTSUPP;
     if (!netif_device_present(dev))
         return -ENODEV;
     return ops->ndo_change_carrier(dev, new_carrier);
 }
 
 /**
  *  dev_get_phys_port_id - Get device physical port ID
  *  @dev: device
  *  @ppid: port ID
  *
  *  Get device physical port ID
  */
 int dev_get_phys_port_id(struct net_device *dev,
              struct netdev_phys_item_id *ppid)
 {
     const struct net_device_ops *ops = dev->netdev_ops;
 
     if (!ops->ndo_get_phys_port_id)
         return -EOPNOTSUPP;
     return ops->ndo_get_phys_port_id(dev, ppid);
 }
 
 /**
  *  dev_get_phys_port_name - Get device physical port name
  *  @dev: device
  *  @name: port name
  *  @len: limit of bytes to copy to name
  *
  *  Get device physical port name
  */
 int dev_get_phys_port_name(struct net_device *dev,
                char *name, size_t len)
 {
     const struct net_device_ops *ops = dev->netdev_ops;
     int err;
 
     if (ops->ndo_get_phys_port_name) {
         err = ops->ndo_get_phys_port_name(dev, name, len);
         if (err != -EOPNOTSUPP)
             return err;
     }
     return devlink_compat_phys_port_name_get(dev, name, len);
 }
 
 /**
  *  dev_get_port_parent_id - Get the device's port parent identifier
  *  @dev: network device
  *  @ppid: pointer to a storage for the port's parent identifier
  *  @recurse: allow/disallow recursion to lower devices
  *
  *  Get the devices's port parent identifier
  */
 int dev_get_port_parent_id(struct net_device *dev,
                struct netdev_phys_item_id *ppid,
                bool recurse)
 {
     const struct net_device_ops *ops = dev->netdev_ops;
     struct netdev_phys_item_id first = { };
     struct net_device *lower_dev;
     struct list_head *iter;
     int err;
 
     if (ops->ndo_get_port_parent_id) {
         err = ops->ndo_get_port_parent_id(dev, ppid);
         if (err != -EOPNOTSUPP)
             return err;
     }
 
     err = devlink_compat_switch_id_get(dev, ppid);
     if (!recurse || err != -EOPNOTSUPP)
         return err;
 
     netdev_for_each_lower_dev(dev, lower_dev, iter) {
         err = dev_get_port_parent_id(lower_dev, ppid, true);
         if (err)
             break;
         if (!first.id_len)
             first = *ppid;
         else if (memcmp(&first, ppid, sizeof(*ppid)))
             return -EOPNOTSUPP;
     }
 
     return err;
 }
 EXPORT_SYMBOL(dev_get_port_parent_id);
 
 /**
  *  netdev_port_same_parent_id - Indicate if two network devices have
  *  the same port parent identifier
  *  @a: first network device
  *  @b: second network device
  */
 bool netdev_port_same_parent_id(struct net_device *a, struct net_device *b)
 {
     struct netdev_phys_item_id a_id = { };
     struct netdev_phys_item_id b_id = { };
 
     if (dev_get_port_parent_id(a, &a_id, true) ||
         dev_get_port_parent_id(b, &b_id, true))
         return false;
 
     return netdev_phys_item_id_same(&a_id, &b_id);
 }
 EXPORT_SYMBOL(netdev_port_same_parent_id);
 
 /**
  *  dev_change_proto_down - set carrier according to proto_down.
  *
  *  @dev: device
  *  @proto_down: new value
  */
 int dev_change_proto_down(struct net_device *dev, bool proto_down)
 {
     if (!(dev->priv_flags & IFF_CHANGE_PROTO_DOWN))
         return -EOPNOTSUPP;
     if (!netif_device_present(dev))
         return -ENODEV;
     if (proto_down)
         netif_carrier_off(dev);
     else
         netif_carrier_on(dev);
     dev->proto_down = proto_down;
     return 0;
 }
 
 /**
  *  dev_change_proto_down_reason - proto down reason
  *
  *  @dev: device
  *  @mask: proto down mask
  *  @value: proto down value
  */
 void dev_change_proto_down_reason(struct net_device *dev, unsigned long mask,
                   u32 value)
 {
     int b;
 
     if (!mask) {
         dev->proto_down_reason = value;
     } else {
         for_each_set_bit(b, &mask, 32) {
             if (value & (1 << b))
                 dev->proto_down_reason |= BIT(b);
             else
                 dev->proto_down_reason &= ~BIT(b);
         }
     }
 }
 
 struct bpf_xdp_link {
     struct bpf_link link;
     struct net_device *dev; /* protected by rtnl_lock, no refcnt held */
     int flags;
 };
 
 static enum bpf_xdp_mode dev_xdp_mode(struct net_device *dev, u32 flags)
 {
     if (flags & XDP_FLAGS_HW_MODE)
         return XDP_MODE_HW;
     if (flags & XDP_FLAGS_DRV_MODE)
         return XDP_MODE_DRV;
     if (flags & XDP_FLAGS_SKB_MODE)
         return XDP_MODE_SKB;
     return dev->netdev_ops->ndo_bpf ? XDP_MODE_DRV : XDP_MODE_SKB;
 }
 
 static bpf_op_t dev_xdp_bpf_op(struct net_device *dev, enum bpf_xdp_mode mode)
 {
     switch (mode) {
     case XDP_MODE_SKB:
         return generic_xdp_install;
     case XDP_MODE_DRV:
     case XDP_MODE_HW:
         return dev->netdev_ops->ndo_bpf;
     default:
         return NULL;
     }
 }
 
 static struct bpf_xdp_link *dev_xdp_link(struct net_device *dev,
                      enum bpf_xdp_mode mode)
 {
     return dev->xdp_state[mode].link;
 }
 
 static struct bpf_prog *dev_xdp_prog(struct net_device *dev,
                      enum bpf_xdp_mode mode)
 {
     struct bpf_xdp_link *link = dev_xdp_link(dev, mode);
 
     if (link)
         return link->link.prog;
     return dev->xdp_state[mode].prog;
 }
 
 u8 dev_xdp_prog_count(struct net_device *dev)
 {
     u8 count = 0;
     int i;
 
     for (i = 0; i < __MAX_XDP_MODE; i++)
         if (dev->xdp_state[i].prog || dev->xdp_state[i].link)
             count++;
     return count;
 }
 EXPORT_SYMBOL_GPL(dev_xdp_prog_count);
 
 u32 dev_xdp_prog_id(struct net_device *dev, enum bpf_xdp_mode mode)
 {
     struct bpf_prog *prog = dev_xdp_prog(dev, mode);
 
     return prog ? prog->aux->id : 0;
 }
 
 static void dev_xdp_set_link(struct net_device *dev, enum bpf_xdp_mode mode,
                  struct bpf_xdp_link *link)
 {
     dev->xdp_state[mode].link = link;
     dev->xdp_state[mode].prog = NULL;
 }
 
 static void dev_xdp_set_prog(struct net_device *dev, enum bpf_xdp_mode mode,
                  struct bpf_prog *prog)
 {
     dev->xdp_state[mode].link = NULL;
     dev->xdp_state[mode].prog = prog;
 }
 
 static int dev_xdp_install(struct net_device *dev, enum bpf_xdp_mode mode,
                bpf_op_t bpf_op, struct netlink_ext_ack *extack,
                u32 flags, struct bpf_prog *prog)
 {
     struct netdev_bpf xdp;
     int err;
 
     memset(&xdp, 0, sizeof(xdp));
     xdp.command = mode == XDP_MODE_HW ? XDP_SETUP_PROG_HW : XDP_SETUP_PROG;
     xdp.extack = extack;
     xdp.flags = flags;
     xdp.prog = prog;
 
     /* Drivers assume refcnt is already incremented (i.e, prog pointer is
      * "moved" into driver), so they don't increment it on their own, but
      * they do decrement refcnt when program is detached or replaced.
      * Given net_device also owns link/prog, we need to bump refcnt here
      * to prevent drivers from underflowing it.
      */
     if (prog)
         bpf_prog_inc(prog);
     err = bpf_op(dev, &xdp);
     if (err) {
         if (prog)
             bpf_prog_put(prog);
         return err;
     }
 
     if (mode != XDP_MODE_HW)
         bpf_prog_change_xdp(dev_xdp_prog(dev, mode), prog);
 
     return 0;
 }
 
 static void dev_xdp_uninstall(struct net_device *dev)
 {
     struct bpf_xdp_link *link;
     struct bpf_prog *prog;
     enum bpf_xdp_mode mode;
     bpf_op_t bpf_op;
 
     ASSERT_RTNL();
 
     for (mode = XDP_MODE_SKB; mode < __MAX_XDP_MODE; mode++) {
         prog = dev_xdp_prog(dev, mode);
         if (!prog)
             continue;
 
         bpf_op = dev_xdp_bpf_op(dev, mode);
         if (!bpf_op)
             continue;
 
         WARN_ON(dev_xdp_install(dev, mode, bpf_op, NULL, 0, NULL));
 
         /* auto-detach link from net device */
         link = dev_xdp_link(dev, mode);
         if (link)
             link->dev = NULL;
         else
             bpf_prog_put(prog);
 
         dev_xdp_set_link(dev, mode, NULL);
     }
 }
 
 static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack,
               struct bpf_xdp_link *link, struct bpf_prog *new_prog,
               struct bpf_prog *old_prog, u32 flags)
 {
     unsigned int num_modes = hweight32(flags & XDP_FLAGS_MODES);
     struct bpf_prog *cur_prog;
     struct net_device *upper;
     struct list_head *iter;
     enum bpf_xdp_mode mode;
     bpf_op_t bpf_op;
     int err;
 
     ASSERT_RTNL();
 
     /* either link or prog attachment, never both */
     if (link && (new_prog || old_prog))
         return -EINVAL;
     /* link supports only XDP mode flags */
     if (link && (flags & ~XDP_FLAGS_MODES)) {
         NL_SET_ERR_MSG(extack, "Invalid XDP flags for BPF link attachment");
         return -EINVAL;
     }
     /* just one XDP mode bit should be set, zero defaults to drv/skb mode */
     if (num_modes > 1) {
         NL_SET_ERR_MSG(extack, "Only one XDP mode flag can be set");
         return -EINVAL;
     }
     /* avoid ambiguity if offload + drv/skb mode progs are both loaded */
     if (!num_modes && dev_xdp_prog_count(dev) > 1) {
         NL_SET_ERR_MSG(extack,
                    "More than one program loaded, unset mode is ambiguous");
         return -EINVAL;
     }
     /* old_prog != NULL implies XDP_FLAGS_REPLACE is set */
     if (old_prog && !(flags & XDP_FLAGS_REPLACE)) {
         NL_SET_ERR_MSG(extack, "XDP_FLAGS_REPLACE is not specified");
         return -EINVAL;
     }
 
     mode = dev_xdp_mode(dev, flags);
     /* can't replace attached link */
     if (dev_xdp_link(dev, mode)) {
         NL_SET_ERR_MSG(extack, "Can't replace active BPF XDP link");
         return -EBUSY;
     }
 
     /* don't allow if an upper device already has a program */
     netdev_for_each_upper_dev_rcu(dev, upper, iter) {
         if (dev_xdp_prog_count(upper) > 0) {
             NL_SET_ERR_MSG(extack, "Cannot attach when an upper device already has a program");
             return -EEXIST;
         }
     }
 
     cur_prog = dev_xdp_prog(dev, mode);
     /* can't replace attached prog with link */
     if (link && cur_prog) {
         NL_SET_ERR_MSG(extack, "Can't replace active XDP program with BPF link");
         return -EBUSY;
     }
     if ((flags & XDP_FLAGS_REPLACE) && cur_prog != old_prog) {
         NL_SET_ERR_MSG(extack, "Active program does not match expected");
         return -EEXIST;
     }
 
     /* put effective new program into new_prog */
     if (link)
         new_prog = link->link.prog;
 
     if (new_prog) {
         bool offload = mode == XDP_MODE_HW;
         enum bpf_xdp_mode other_mode = mode == XDP_MODE_SKB
                            ? XDP_MODE_DRV : XDP_MODE_SKB;
 
         if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && cur_prog) {
             NL_SET_ERR_MSG(extack, "XDP program already attached");
             return -EBUSY;
         }
         if (!offload && dev_xdp_prog(dev, other_mode)) {
             NL_SET_ERR_MSG(extack, "Native and generic XDP can't be active at the same time");
             return -EEXIST;
         }
         if (!offload && bpf_prog_is_dev_bound(new_prog->aux)) {
             NL_SET_ERR_MSG(extack, "Using device-bound program without HW_MODE flag is not supported");
             return -EINVAL;
         }
         if (new_prog->expected_attach_type == BPF_XDP_DEVMAP) {
             NL_SET_ERR_MSG(extack, "BPF_XDP_DEVMAP programs can not be attached to a device");
             return -EINVAL;
         }
         if (new_prog->expected_attach_type == BPF_XDP_CPUMAP) {
             NL_SET_ERR_MSG(extack, "BPF_XDP_CPUMAP programs can not be attached to a device");
             return -EINVAL;
         }
     }
 
     /* don't call drivers if the effective program didn't change */
     if (new_prog != cur_prog) {
         bpf_op = dev_xdp_bpf_op(dev, mode);
         if (!bpf_op) {
             NL_SET_ERR_MSG(extack, "Underlying driver does not support XDP in native mode");
             return -EOPNOTSUPP;
         }
 
         err = dev_xdp_install(dev, mode, bpf_op, extack, flags, new_prog);
         if (err)
             return err;
     }
 
     if (link)
         dev_xdp_set_link(dev, mode, link);
     else
         dev_xdp_set_prog(dev, mode, new_prog);
     if (cur_prog)
         bpf_prog_put(cur_prog);
 
     return 0;
 }
 
 static int dev_xdp_attach_link(struct net_device *dev,
                    struct netlink_ext_ack *extack,
                    struct bpf_xdp_link *link)
 {
     return dev_xdp_attach(dev, extack, link, NULL, NULL, link->flags);
 }
 
 static int dev_xdp_detach_link(struct net_device *dev,
                    struct netlink_ext_ack *extack,
                    struct bpf_xdp_link *link)
 {
     enum bpf_xdp_mode mode;
     bpf_op_t bpf_op;
 
     ASSERT_RTNL();
 
     mode = dev_xdp_mode(dev, link->flags);
     if (dev_xdp_link(dev, mode) != link)
         return -EINVAL;
 
     bpf_op = dev_xdp_bpf_op(dev, mode);
     WARN_ON(dev_xdp_install(dev, mode, bpf_op, NULL, 0, NULL));
     dev_xdp_set_link(dev, mode, NULL);
     return 0;
 }
 
 static void bpf_xdp_link_release(struct bpf_link *link)
 {
     struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
 
     rtnl_lock();
 
     /* if racing with net_device's tear down, xdp_link->dev might be
      * already NULL, in which case link was already auto-detached
      */
     if (xdp_link->dev) {
         WARN_ON(dev_xdp_detach_link(xdp_link->dev, NULL, xdp_link));
         xdp_link->dev = NULL;
     }
 
     rtnl_unlock();
 }
 
 static int bpf_xdp_link_detach(struct bpf_link *link)
 {
     bpf_xdp_link_release(link);
     return 0;
 }
 
 static void bpf_xdp_link_dealloc(struct bpf_link *link)
 {
     struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
 
     kfree(xdp_link);
 }
 
 static void bpf_xdp_link_show_fdinfo(const struct bpf_link *link,
                      struct seq_file *seq)
 {
     struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
     u32 ifindex = 0;
 
     rtnl_lock();
     if (xdp_link->dev)
         ifindex = xdp_link->dev->ifindex;
     rtnl_unlock();
 
     seq_printf(seq, "ifindex:\t%u\n", ifindex);
 }
 
 static int bpf_xdp_link_fill_link_info(const struct bpf_link *link,
                        struct bpf_link_info *info)
 {
     struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
     u32 ifindex = 0;
 
     rtnl_lock();
     if (xdp_link->dev)
         ifindex = xdp_link->dev->ifindex;
     rtnl_unlock();
 
     info->xdp.ifindex = ifindex;
     return 0;
 }
 
 static int bpf_xdp_link_update(struct bpf_link *link, struct bpf_prog *new_prog,
                    struct bpf_prog *old_prog)
 {
     struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
     enum bpf_xdp_mode mode;
     bpf_op_t bpf_op;
     int err = 0;
 
     rtnl_lock();
 
     /* link might have been auto-released already, so fail */
     if (!xdp_link->dev) {
         err = -ENOLINK;
         goto out_unlock;
     }
 
     if (old_prog && link->prog != old_prog) {
         err = -EPERM;
         goto out_unlock;
     }
     old_prog = link->prog;
     if (old_prog->type != new_prog->type ||
         old_prog->expected_attach_type != new_prog->expected_attach_type) {
         err = -EINVAL;
         goto out_unlock;
     }
 
     if (old_prog == new_prog) {
         /* no-op, don't disturb drivers */
         bpf_prog_put(new_prog);
         goto out_unlock;
     }
 
     mode = dev_xdp_mode(xdp_link->dev, xdp_link->flags);
     bpf_op = dev_xdp_bpf_op(xdp_link->dev, mode);
     err = dev_xdp_install(xdp_link->dev, mode, bpf_op, NULL,
                   xdp_link->flags, new_prog);
     if (err)
         goto out_unlock;
 
     old_prog = xchg(&link->prog, new_prog);
     bpf_prog_put(old_prog);
 
 out_unlock:
     rtnl_unlock();
     return err;
 }
 
 static const struct bpf_link_ops bpf_xdp_link_lops = {
     .release = bpf_xdp_link_release,
     .dealloc = bpf_xdp_link_dealloc,
     .detach = bpf_xdp_link_detach,
     .show_fdinfo = bpf_xdp_link_show_fdinfo,
     .fill_link_info = bpf_xdp_link_fill_link_info,
     .update_prog = bpf_xdp_link_update,
 };
 
 int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
 {
     struct net *net = current->nsproxy->net_ns;
     struct bpf_link_primer link_primer;
     struct bpf_xdp_link *link;
     struct net_device *dev;
     int err, fd;
 
     rtnl_lock();
     dev = dev_get_by_index(net, attr->link_create.target_ifindex);
     if (!dev) {
         rtnl_unlock();
         return -EINVAL;
     }
 
     link = kzalloc(sizeof(*link), GFP_USER);
     if (!link) {
         err = -ENOMEM;
         goto unlock;
     }
 
     bpf_link_init(&link->link, BPF_LINK_TYPE_XDP, &bpf_xdp_link_lops, prog);
     link->dev = dev;
     link->flags = attr->link_create.flags;
 
     err = bpf_link_prime(&link->link, &link_primer);
     if (err) {
         kfree(link);
         goto unlock;
     }
 
     err = dev_xdp_attach_link(dev, NULL, link);
     rtnl_unlock();
 
     if (err) {
         link->dev = NULL;
         bpf_link_cleanup(&link_primer);
         goto out_put_dev;
     }
 
     fd = bpf_link_settle(&link_primer);
     /* link itself doesn't hold dev's refcnt to not complicate shutdown */
     dev_put(dev);
     return fd;
 
 unlock:
     rtnl_unlock();
 
 out_put_dev:
     dev_put(dev);
     return err;
 }
 
 /**
  *  dev_change_xdp_fd - set or clear a bpf program for a device rx path
  *  @dev: device
  *  @extack: netlink extended ack
  *  @fd: new program fd or negative value to clear
  *  @expected_fd: old program fd that userspace expects to replace or clear
  *  @flags: xdp-related flags
  *
  *  Set or clear a bpf program for a device
  */
 int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
               int fd, int expected_fd, u32 flags)
 {
     enum bpf_xdp_mode mode = dev_xdp_mode(dev, flags);
     struct bpf_prog *new_prog = NULL, *old_prog = NULL;
     int err;
 
     ASSERT_RTNL();
 
     if (fd >= 0) {
         new_prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP,
                          mode != XDP_MODE_SKB);
         if (IS_ERR(new_prog))
             return PTR_ERR(new_prog);
     }
 
     if (expected_fd >= 0) {
         old_prog = bpf_prog_get_type_dev(expected_fd, BPF_PROG_TYPE_XDP,
                          mode != XDP_MODE_SKB);
         if (IS_ERR(old_prog)) {
             err = PTR_ERR(old_prog);
             old_prog = NULL;
             goto err_out;
         }
     }
 
     err = dev_xdp_attach(dev, extack, NULL, new_prog, old_prog, flags);
 
 err_out:
     if (err && new_prog)
         bpf_prog_put(new_prog);
     if (old_prog)
         bpf_prog_put(old_prog);
     return err;
 }
 
 /**
  *  dev_new_index   -   allocate an ifindex
  *  @net: the applicable net namespace
  *
  *  Returns a suitable unique value for a new device interface
  *  number.  The caller must hold the rtnl semaphore or the
  *  dev_base_lock to be sure it remains unique.
  */
 static int dev_new_index(struct net *net)
 {
     int ifindex = net->ifindex;
 
     for (;;) {
         if (++ifindex <= 0)
             ifindex = 1;
         if (!__dev_get_by_index(net, ifindex))
             return net->ifindex = ifindex;
     }
 }
 
 /* Delayed registration/unregisteration */
 LIST_HEAD(net_todo_list);
 DECLARE_WAIT_QUEUE_HEAD(netdev_unregistering_wq);
 
 static void net_set_todo(struct net_device *dev)
 {
     list_add_tail(&dev->todo_list, &net_todo_list);
     atomic_inc(&dev_net(dev)->dev_unreg_count);
 }
 
 static netdev_features_t netdev_sync_upper_features(struct net_device *lower,
     struct net_device *upper, netdev_features_t features)
 {
     netdev_features_t upper_disables = NETIF_F_UPPER_DISABLES;
     netdev_features_t feature;
     int feature_bit;
 
     for_each_netdev_feature(upper_disables, feature_bit) {
         feature = __NETIF_F_BIT(feature_bit);
         if (!(upper->wanted_features & feature)
             && (features & feature)) {
             netdev_dbg(lower, "Dropping feature %pNF, upper dev %s has it off.\n",
                    &feature, upper->name);
             features &= ~feature;
         }
     }
 
     return features;
 }
 
 static void netdev_sync_lower_features(struct net_device *upper,
     struct net_device *lower, netdev_features_t features)
 {
     netdev_features_t upper_disables = NETIF_F_UPPER_DISABLES;
     netdev_features_t feature;
     int feature_bit;
 
     for_each_netdev_feature(upper_disables, feature_bit) {
         feature = __NETIF_F_BIT(feature_bit);
         if (!(features & feature) && (lower->features & feature)) {
             netdev_dbg(upper, "Disabling feature %pNF on lower dev %s.\n",
                    &feature, lower->name);
             lower->wanted_features &= ~feature;
             __netdev_update_features(lower);
 
             if (unlikely(lower->features & feature))
                 netdev_WARN(upper, "failed to disable %pNF on %s!\n",
                         &feature, lower->name);
             else
                 netdev_features_change(lower);
         }
     }
 }
 
 static netdev_features_t netdev_fix_features(struct net_device *dev,
     netdev_features_t features)
 {
     /* Fix illegal checksum combinations */
     if ((features & NETIF_F_HW_CSUM) &&
         (features & (NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM))) {
         netdev_warn(dev, "mixed HW and IP checksum settings.\n");
         features &= ~(NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM);
     }
 
     /* TSO requires that SG is present as well. */
     if ((features & NETIF_F_ALL_TSO) && !(features & NETIF_F_SG)) {
         netdev_dbg(dev, "Dropping TSO features since no SG feature.\n");
         features &= ~NETIF_F_ALL_TSO;
     }
 
     if ((features & NETIF_F_TSO) && !(features & NETIF_F_HW_CSUM) &&
                     !(features & NETIF_F_IP_CSUM)) {
         netdev_dbg(dev, "Dropping TSO features since no CSUM feature.\n");
         features &= ~NETIF_F_TSO;
         features &= ~NETIF_F_TSO_ECN;
     }
 
     if ((features & NETIF_F_TSO6) && !(features & NETIF_F_HW_CSUM) &&
                      !(features & NETIF_F_IPV6_CSUM)) {
         netdev_dbg(dev, "Dropping TSO6 features since no CSUM feature.\n");
         features &= ~NETIF_F_TSO6;
     }
 
     /* TSO with IPv4 ID mangling requires IPv4 TSO be enabled */
     if ((features & NETIF_F_TSO_MANGLEID) && !(features & NETIF_F_TSO))
         features &= ~NETIF_F_TSO_MANGLEID;
 
     /* TSO ECN requires that TSO is present as well. */
     if ((features & NETIF_F_ALL_TSO) == NETIF_F_TSO_ECN)
         features &= ~NETIF_F_TSO_ECN;
 
     /* Software GSO depends on SG. */
     if ((features & NETIF_F_GSO) && !(features & NETIF_F_SG)) {
         netdev_dbg(dev, "Dropping NETIF_F_GSO since no SG feature.\n");
         features &= ~NETIF_F_GSO;
     }
 
     /* GSO partial features require GSO partial be set */
     if ((features & dev->gso_partial_features) &&
         !(features & NETIF_F_GSO_PARTIAL)) {
         netdev_dbg(dev,
                "Dropping partially supported GSO features since no GSO partial.\n");
         features &= ~dev->gso_partial_features;
     }
 
     if (!(features & NETIF_F_RXCSUM)) {
         /* NETIF_F_GRO_HW implies doing RXCSUM since every packet
          * successfully merged by hardware must also have the
          * checksum verified by hardware.  If the user does not
          * want to enable RXCSUM, logically, we should disable GRO_HW.
          */
         if (features & NETIF_F_GRO_HW) {
             netdev_dbg(dev, "Dropping NETIF_F_GRO_HW since no RXCSUM feature.\n");
             features &= ~NETIF_F_GRO_HW;
         }
     }
 
     /* LRO/HW-GRO features cannot be combined with RX-FCS */
     if (features & NETIF_F_RXFCS) {
         if (features & NETIF_F_LRO) {
             netdev_dbg(dev, "Dropping LRO feature since RX-FCS is requested.\n");
             features &= ~NETIF_F_LRO;
         }
 
         if (features & NETIF_F_GRO_HW) {
             netdev_dbg(dev, "Dropping HW-GRO feature since RX-FCS is requested.\n");
             features &= ~NETIF_F_GRO_HW;
         }
     }
 
     if ((features & NETIF_F_GRO_HW) && (features & NETIF_F_LRO)) {
         netdev_dbg(dev, "Dropping LRO feature since HW-GRO is requested.\n");
         features &= ~NETIF_F_LRO;
     }
 
     if (features & NETIF_F_HW_TLS_TX) {
         bool ip_csum = (features & (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM)) ==
             (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM);
         bool hw_csum = features & NETIF_F_HW_CSUM;
 
         if (!ip_csum && !hw_csum) {
             netdev_dbg(dev, "Dropping TLS TX HW offload feature since no CSUM feature.\n");
             features &= ~NETIF_F_HW_TLS_TX;
         }
     }
 
     if ((features & NETIF_F_HW_TLS_RX) && !(features & NETIF_F_RXCSUM)) {
         netdev_dbg(dev, "Dropping TLS RX HW offload feature since no RXCSUM feature.\n");
         features &= ~NETIF_F_HW_TLS_RX;
     }
 
     return features;
 }
 
 int __netdev_update_features(struct net_device *dev)
 {
     struct net_device *upper, *lower;
     netdev_features_t features;
     struct list_head *iter;
     int err = -1;
 
     ASSERT_RTNL();
 
     features = netdev_get_wanted_features(dev);
 
     if (dev->netdev_ops->ndo_fix_features)
         features = dev->netdev_ops->ndo_fix_features(dev, features);
 
     /* driver might be less strict about feature dependencies */
     features = netdev_fix_features(dev, features);
 
     /* some features can't be enabled if they're off on an upper device */
     netdev_for_each_upper_dev_rcu(dev, upper, iter)
         features = netdev_sync_upper_features(dev, upper, features);
 
     if (dev->features == features)
         goto sync_lower;
 
     netdev_dbg(dev, "Features changed: %pNF -> %pNF\n",
         &dev->features, &features);
 
     if (dev->netdev_ops->ndo_set_features)
         err = dev->netdev_ops->ndo_set_features(dev, features);
     else
         err = 0;
 
     if (unlikely(err < 0)) {
         netdev_err(dev,
             "set_features() failed (%d); wanted %pNF, left %pNF\n",
             err, &features, &dev->features);
         /* return non-0 since some features might have changed and
          * it's better to fire a spurious notification than miss it
          */
         return -1;
     }
 
 sync_lower:
     /* some features must be disabled on lower devices when disabled
      * on an upper device (think: bonding master or bridge)
      */
     netdev_for_each_lower_dev(dev, lower, iter)
         netdev_sync_lower_features(dev, lower, features);
 
     if (!err) {
         netdev_features_t diff = features ^ dev->features;
 
         if (diff & NETIF_F_RX_UDP_TUNNEL_PORT) {
             /* udp_tunnel_{get,drop}_rx_info both need
              * NETIF_F_RX_UDP_TUNNEL_PORT enabled on the
              * device, or they won't do anything.
              * Thus we need to update dev->features
              * *before* calling udp_tunnel_get_rx_info,
              * but *after* calling udp_tunnel_drop_rx_info.
              */
             if (features & NETIF_F_RX_UDP_TUNNEL_PORT) {
                 dev->features = features;
                 udp_tunnel_get_rx_info(dev);
             } else {
                 udp_tunnel_drop_rx_info(dev);
             }
         }
 
         if (diff & NETIF_F_HW_VLAN_CTAG_FILTER) {
             if (features & NETIF_F_HW_VLAN_CTAG_FILTER) {
                 dev->features = features;
                 err |= vlan_get_rx_ctag_filter_info(dev);
             } else {
                 vlan_drop_rx_ctag_filter_info(dev);
             }
         }
 
         if (diff & NETIF_F_HW_VLAN_STAG_FILTER) {
             if (features & NETIF_F_HW_VLAN_STAG_FILTER) {
                 dev->features = features;
                 err |= vlan_get_rx_stag_filter_info(dev);
             } else {
                 vlan_drop_rx_stag_filter_info(dev);
             }
         }
 
         dev->features = features;
     }
 
     return err < 0 ? 0 : 1;
 }
 
 /**
  *  netdev_update_features - recalculate device features
  *  @dev: the device to check
  *
  *  Recalculate dev->features set and send notifications if it
  *  has changed. Should be called after driver or hardware dependent
  *  conditions might have changed that influence the features.
  */
 void netdev_update_features(struct net_device *dev)
 {
     if (__netdev_update_features(dev))
         netdev_features_change(dev);
 }
 EXPORT_SYMBOL(netdev_update_features);
 
 /**
  *  netdev_change_features - recalculate device features
  *  @dev: the device to check
  *
  *  Recalculate dev->features set and send notifications even
  *  if they have not changed. Should be called instead of
  *  netdev_update_features() if also dev->vlan_features might
  *  have changed to allow the changes to be propagated to stacked
  *  VLAN devices.
  */
 void netdev_change_features(struct net_device *dev)
 {
     __netdev_update_features(dev);
     netdev_features_change(dev);
 }
 EXPORT_SYMBOL(netdev_change_features);
 
 /**
  *  netif_stacked_transfer_operstate -  transfer operstate
  *  @rootdev: the root or lower level device to transfer state from
  *  @dev: the device to transfer operstate to
  *
  *  Transfer operational state from root to device. This is normally
  *  called when a stacking relationship exists between the root
  *  device and the device(a leaf device).
  */
 void netif_stacked_transfer_operstate(const struct net_device *rootdev,
                     struct net_device *dev)
 {
     if (rootdev->operstate == IF_OPER_DORMANT)
         netif_dormant_on(dev);
     else
         netif_dormant_off(dev);
 
     if (rootdev->operstate == IF_OPER_TESTING)
         netif_testing_on(dev);
     else
         netif_testing_off(dev);
 
     if (netif_carrier_ok(rootdev))
         netif_carrier_on(dev);
     else
         netif_carrier_off(dev);
 }
 EXPORT_SYMBOL(netif_stacked_transfer_operstate);
 
 static int netif_alloc_rx_queues(struct net_device *dev)
 {
     unsigned int i, count = dev->num_rx_queues;
     struct netdev_rx_queue *rx;
     size_t sz = count * sizeof(*rx);
     int err = 0;
 
     BUG_ON(count < 1);
 
     rx = kvzalloc(sz, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
     if (!rx)
         return -ENOMEM;
 
     dev->_rx = rx;
 
     for (i = 0; i < count; i++) {
         rx[i].dev = dev;
 
         /* XDP RX-queue setup */
         err = xdp_rxq_info_reg(&rx[i].xdp_rxq, dev, i, 0);
         if (err < 0)
             goto err_rxq_info;
     }
     return 0;
 
 err_rxq_info:
     /* Rollback successful reg's and free other resources */
     while (i--)
         xdp_rxq_info_unreg(&rx[i].xdp_rxq);
     kvfree(dev->_rx);
     dev->_rx = NULL;
     return err;
 }
 
 static void netif_free_rx_queues(struct net_device *dev)
 {
     unsigned int i, count = dev->num_rx_queues;
 
     /* netif_alloc_rx_queues alloc failed, resources have been unreg'ed */
     if (!dev->_rx)
         return;
 
     for (i = 0; i < count; i++)
         xdp_rxq_info_unreg(&dev->_rx[i].xdp_rxq);
 
     kvfree(dev->_rx);
 }
 
 static void netdev_init_one_queue(struct net_device *dev,
                   struct netdev_queue *queue, void *_unused)
 {
     /* Initialize queue lock */
     spin_lock_init(&queue->_xmit_lock);
     netdev_set_xmit_lockdep_class(&queue->_xmit_lock, dev->type);
     queue->xmit_lock_owner = -1;
     netdev_queue_numa_node_write(queue, NUMA_NO_NODE);
     queue->dev = dev;
 #ifdef CONFIG_BQL
     dql_init(&queue->dql, HZ);
 #endif
 }
 
 static void netif_free_tx_queues(struct net_device *dev)
 {
     kvfree(dev->_tx);
 }
 
 static int netif_alloc_netdev_queues(struct net_device *dev)
 {
     unsigned int count = dev->num_tx_queues;
     struct netdev_queue *tx;
     size_t sz = count * sizeof(*tx);
 
     if (count < 1 || count > 0xffff)
         return -EINVAL;
 
     tx = kvzalloc(sz, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
     if (!tx)
         return -ENOMEM;
 
     dev->_tx = tx;
 
     netdev_for_each_tx_queue(dev, netdev_init_one_queue, NULL);
     spin_lock_init(&dev->tx_global_lock);
 
     return 0;
 }
 
 void netif_tx_stop_all_queues(struct net_device *dev)
 {
     unsigned int i;
 
     for (i = 0; i < dev->num_tx_queues; i++) {
         struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
 
         netif_tx_stop_queue(txq);
     }
 }
 EXPORT_SYMBOL(netif_tx_stop_all_queues);
 
 /**
  * register_netdevice() - register a network device
  * @dev: device to register
  *
  * Take a prepared network device structure and make it externally accessible.
  * A %NETDEV_REGISTER message is sent to the netdev notifier chain.
  * Callers must hold the rtnl lock - you may want register_netdev()
  * instead of this.
  */
 int register_netdevice(struct net_device *dev)
 {
     int ret;
     struct net *net = dev_net(dev);
 
     BUILD_BUG_ON(sizeof(netdev_features_t) * BITS_PER_BYTE <
              NETDEV_FEATURE_COUNT);
     BUG_ON(dev_boot_phase);
     ASSERT_RTNL();
 
     might_sleep();
 
     /* When net_device's are persistent, this will be fatal. */
     BUG_ON(dev->reg_state != NETREG_UNINITIALIZED);
     BUG_ON(!net);
 
     ret = ethtool_check_ops(dev->ethtool_ops);
     if (ret)
         return ret;
 
     spin_lock_init(&dev->addr_list_lock);
     netdev_set_addr_lockdep_class(dev);
 
     ret = dev_get_valid_name(net, dev, dev->name);
     if (ret < 0)
         goto out;
 
     ret = -ENOMEM;
     dev->name_node = netdev_name_node_head_alloc(dev);
     if (!dev->name_node)
         goto out;
 
     /* Init, if this function is available */
     if (dev->netdev_ops->ndo_init) {
         ret = dev->netdev_ops->ndo_init(dev);
         if (ret) {
             if (ret > 0)
                 ret = -EIO;
             goto err_free_name;
         }
     }
 
     if (((dev->hw_features | dev->features) &
          NETIF_F_HW_VLAN_CTAG_FILTER) &&
         (!dev->netdev_ops->ndo_vlan_rx_add_vid ||
          !dev->netdev_ops->ndo_vlan_rx_kill_vid)) {
         netdev_WARN(dev, "Buggy VLAN acceleration in driver!\n");
         ret = -EINVAL;
         goto err_uninit;
     }
 
     ret = -EBUSY;
     if (!dev->ifindex)
         dev->ifindex = dev_new_index(net);
     else if (__dev_get_by_index(net, dev->ifindex))
         goto err_uninit;
 
     /* Transfer changeable features to wanted_features and enable
      * software offloads (GSO and GRO).
      */
     dev->hw_features |= (NETIF_F_SOFT_FEATURES | NETIF_F_SOFT_FEATURES_OFF);
     dev->features |= NETIF_F_SOFT_FEATURES;
 
     if (dev->udp_tunnel_nic_info) {
         dev->features |= NETIF_F_RX_UDP_TUNNEL_PORT;
         dev->hw_features |= NETIF_F_RX_UDP_TUNNEL_PORT;
     }
 
     dev->wanted_features = dev->features & dev->hw_features;
 
     if (!(dev->flags & IFF_LOOPBACK))
         dev->hw_features |= NETIF_F_NOCACHE_COPY;
 
     /* If IPv4 TCP segmentation offload is supported we should also
      * allow the device to enable segmenting the frame with the option
      * of ignoring a static IP ID value.  This doesn't enable the
      * feature itself but allows the user to enable it later.
      */
     if (dev->hw_features & NETIF_F_TSO)
         dev->hw_features |= NETIF_F_TSO_MANGLEID;
     if (dev->vlan_features & NETIF_F_TSO)
         dev->vlan_features |= NETIF_F_TSO_MANGLEID;
     if (dev->mpls_features & NETIF_F_TSO)
         dev->mpls_features |= NETIF_F_TSO_MANGLEID;
     if (dev->hw_enc_features & NETIF_F_TSO)
         dev->hw_enc_features |= NETIF_F_TSO_MANGLEID;
 
     /* Make NETIF_F_HIGHDMA inheritable to VLAN devices.
      */
     dev->vlan_features |= NETIF_F_HIGHDMA;
 
     /* Make NETIF_F_SG inheritable to tunnel devices.
      */
     dev->hw_enc_features |= NETIF_F_SG | NETIF_F_GSO_PARTIAL;
 
     /* Make NETIF_F_SG inheritable to MPLS.
      */
     dev->mpls_features |= NETIF_F_SG;
 
     ret = call_netdevice_notifiers(NETDEV_POST_INIT, dev);
     ret = notifier_to_errno(ret);
     if (ret)
         goto err_uninit;
 
     ret = netdev_register_kobject(dev);
     write_lock(&dev_base_lock);
     dev->reg_state = ret ? NETREG_UNREGISTERED : NETREG_REGISTERED;
     write_unlock(&dev_base_lock);
     if (ret)
         goto err_uninit;
 
     __netdev_update_features(dev);
 
     /*
      *  Default initial state at registry is that the
      *  device is present.
      */
 
     set_bit(__LINK_STATE_PRESENT, &dev->state);
 
     linkwatch_init_dev(dev);
 
     dev_init_scheduler(dev);
 
     netdev_hold(dev, &dev->dev_registered_tracker, GFP_KERNEL);
     list_netdevice(dev);
 
     add_device_randomness(dev->dev_addr, dev->addr_len);
 
     /* If the device has permanent device address, driver should
      * set dev_addr and also addr_assign_type should be set to
      * NET_ADDR_PERM (default value).
      */
     if (dev->addr_assign_type == NET_ADDR_PERM)
         memcpy(dev->perm_addr, dev->dev_addr, dev->addr_len);
 
     /* Notify protocols, that a new device appeared. */
     ret = call_netdevice_notifiers(NETDEV_REGISTER, dev);
     ret = notifier_to_errno(ret);
     if (ret) {
         /* Expect explicit free_netdev() on failure */
         dev->needs_free_netdev = false;
         unregister_netdevice_queue(dev, NULL);
         goto out;
     }
     /*
      *  Prevent userspace races by waiting until the network
      *  device is fully setup before sending notifications.
      */
     if (!dev->rtnl_link_ops ||
         dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
         rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL);
 
 out:
     return ret;
 
 err_uninit:
     if (dev->netdev_ops->ndo_uninit)
         dev->netdev_ops->ndo_uninit(dev);
     if (dev->priv_destructor)
         dev->priv_destructor(dev);
 err_free_name:
     netdev_name_node_free(dev->name_node);
     goto out;
 }
 EXPORT_SYMBOL(register_netdevice);
 
 /**
  *  init_dummy_netdev   - init a dummy network device for NAPI
  *  @dev: device to init
  *
  *  This takes a network device structure and initialize the minimum
  *  amount of fields so it can be used to schedule NAPI polls without
  *  registering a full blown interface. This is to be used by drivers
  *  that need to tie several hardware interfaces to a single NAPI
  *  poll scheduler due to HW limitations.
  */
 int init_dummy_netdev(struct net_device *dev)
 {
     /* Clear everything. Note we don't initialize spinlocks
      * are they aren't supposed to be taken by any of the
      * NAPI code and this dummy netdev is supposed to be
      * only ever used for NAPI polls
      */
     memset(dev, 0, sizeof(struct net_device));
 
     /* make sure we BUG if trying to hit standard
      * register/unregister code path
      */
     dev->reg_state = NETREG_DUMMY;
 
     /* NAPI wants this */
     INIT_LIST_HEAD(&dev->napi_list);
 
     /* a dummy interface is started by default */
     set_bit(__LINK_STATE_PRESENT, &dev->state);
     set_bit(__LINK_STATE_START, &dev->state);
 
     /* napi_busy_loop stats accounting wants this */
     dev_net_set(dev, &init_net);
 
     /* Note : We dont allocate pcpu_refcnt for dummy devices,
      * because users of this 'device' dont need to change
      * its refcount.
      */
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(init_dummy_netdev);
 
 
 /**
  *  register_netdev - register a network device
  *  @dev: device to register
  *
  *  Take a completed network device structure and add it to the kernel
  *  interfaces. A %NETDEV_REGISTER message is sent to the netdev notifier
  *  chain. 0 is returned on success. A negative errno code is returned
  *  on a failure to set up the device, or if the name is a duplicate.
  *
  *  This is a wrapper around register_netdevice that takes the rtnl semaphore
  *  and expands the device name if you passed a format string to
  *  alloc_netdev.
  */
 int register_netdev(struct net_device *dev)
 {
     int err;
 
     if (rtnl_lock_killable())
         return -EINTR;
     err = register_netdevice(dev);
     rtnl_unlock();
     return err;
 }
 EXPORT_SYMBOL(register_netdev);
 
 int netdev_refcnt_read(const struct net_device *dev)
 {
 #ifdef CONFIG_PCPU_DEV_REFCNT
     int i, refcnt = 0;
 
     for_each_possible_cpu(i)
         refcnt += *per_cpu_ptr(dev->pcpu_refcnt, i);
     return refcnt;
 #else
     return refcount_read(&dev->dev_refcnt);
 #endif
 }
 EXPORT_SYMBOL(netdev_refcnt_read);
 
 int netdev_unregister_timeout_secs __read_mostly = 10;
 
 #define WAIT_REFS_MIN_MSECS 1
 #define WAIT_REFS_MAX_MSECS 250
 /**
  * netdev_wait_allrefs_any - wait until all references are gone.
  * @list: list of net_devices to wait on
  *
  * This is called when unregistering network devices.
  *
  * Any protocol or device that holds a reference should register
  * for netdevice notification, and cleanup and put back the
  * reference if they receive an UNREGISTER event.
  * We can get stuck here if buggy protocols don't correctly
  * call dev_put.
  */
 static struct net_device *netdev_wait_allrefs_any(struct list_head *list)
 {
     unsigned long rebroadcast_time, warning_time;
     struct net_device *dev;
     int wait = 0;
 
     rebroadcast_time = warning_time = jiffies;
 
     list_for_each_entry(dev, list, todo_list)
         if (netdev_refcnt_read(dev) == 1)
             return dev;
 
     while (true) {
         if (time_after(jiffies, rebroadcast_time + 1 * HZ)) {
             rtnl_lock();
 
             /* Rebroadcast unregister notification */
             list_for_each_entry(dev, list, todo_list)
                 call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
 
             __rtnl_unlock();
             rcu_barrier();
             rtnl_lock();
 
             list_for_each_entry(dev, list, todo_list)
                 if (test_bit(__LINK_STATE_LINKWATCH_PENDING,
                          &dev->state)) {
                     /* We must not have linkwatch events
                      * pending on unregister. If this
                      * happens, we simply run the queue
                      * unscheduled, resulting in a noop
                      * for this device.
                      */
                     linkwatch_run_queue();
                     break;
                 }
 
             __rtnl_unlock();
 
             rebroadcast_time = jiffies;
         }
 
         if (!wait) {
             rcu_barrier();
             wait = WAIT_REFS_MIN_MSECS;
         } else {
             msleep(wait);
             wait = min(wait << 1, WAIT_REFS_MAX_MSECS);
         }
 
         list_for_each_entry(dev, list, todo_list)
             if (netdev_refcnt_read(dev) == 1)
                 return dev;
 
         if (time_after(jiffies, warning_time +
                    READ_ONCE(netdev_unregister_timeout_secs) * HZ)) {
             list_for_each_entry(dev, list, todo_list) {
                 pr_emerg("unregister_netdevice: waiting for %s to become free. Usage count = %d\n",
                      dev->name, netdev_refcnt_read(dev));
                 ref_tracker_dir_print(&dev->refcnt_tracker, 10);
             }
 
             warning_time = jiffies;
         }
     }
 }
 
 /* The sequence is:
  *
  *  rtnl_lock();
  *  ...
  *  register_netdevice(x1);
  *  register_netdevice(x2);
  *  ...
  *  unregister_netdevice(y1);
  *  unregister_netdevice(y2);
  *      ...
  *  rtnl_unlock();
  *  free_netdev(y1);
  *  free_netdev(y2);
  *
  * We are invoked by rtnl_unlock().
  * This allows us to deal with problems:
  * 1) We can delete sysfs objects which invoke hotplug
  *    without deadlocking with linkwatch via keventd.
  * 2) Since we run with the RTNL semaphore not held, we can sleep
  *    safely in order to wait for the netdev refcnt to drop to zero.
  *
  * We must not return until all unregister events added during
  * the interval the lock was held have been completed.
  */
 void netdev_run_todo(void)
 {
     struct net_device *dev, *tmp;
     struct list_head list;
 #ifdef CONFIG_LOCKDEP
     struct list_head unlink_list;
 
     list_replace_init(&net_unlink_list, &unlink_list);
 
     while (!list_empty(&unlink_list)) {
         struct net_device *dev = list_first_entry(&unlink_list,
                               struct net_device,
                               unlink_list);
         list_del_init(&dev->unlink_list);
         dev->nested_level = dev->lower_level - 1;
     }
 #endif
 
     /* Snapshot list, allow later requests */
     list_replace_init(&net_todo_list, &list);
 
     __rtnl_unlock();
 
     /* Wait for rcu callbacks to finish before next phase */
     if (!list_empty(&list))
         rcu_barrier();
 
     list_for_each_entry_safe(dev, tmp, &list, todo_list) {
         if (unlikely(dev->reg_state != NETREG_UNREGISTERING)) {
             netdev_WARN(dev, "run_todo but not unregistering\n");
             list_del(&dev->todo_list);
             continue;
         }
 
         write_lock(&dev_base_lock);
         dev->reg_state = NETREG_UNREGISTERED;
         write_unlock(&dev_base_lock);
         linkwatch_forget_dev(dev);
     }
 
     while (!list_empty(&list)) {
         dev = netdev_wait_allrefs_any(&list);
         list_del(&dev->todo_list);
 
         /* paranoia */
         BUG_ON(netdev_refcnt_read(dev) != 1);
         BUG_ON(!list_empty(&dev->ptype_all));
         BUG_ON(!list_empty(&dev->ptype_specific));
         WARN_ON(rcu_access_pointer(dev->ip_ptr));
         WARN_ON(rcu_access_pointer(dev->ip6_ptr));
 #if IS_ENABLED(CONFIG_DECNET)
         WARN_ON(dev->dn_ptr);
 #endif
         if (dev->priv_destructor)
             dev->priv_destructor(dev);
         if (dev->needs_free_netdev)
             free_netdev(dev);
 
         if (atomic_dec_and_test(&dev_net(dev)->dev_unreg_count))
             wake_up(&netdev_unregistering_wq);
 
         /* Free network device */
         kobject_put(&dev->dev.kobj);
     }
 }
 
 /* Convert net_device_stats to rtnl_link_stats64. rtnl_link_stats64 has
  * all the same fields in the same order as net_device_stats, with only
  * the type differing, but rtnl_link_stats64 may have additional fields
  * at the end for newer counters.
  */
 void netdev_stats_to_stats64(struct rtnl_link_stats64 *stats64,
                  const struct net_device_stats *netdev_stats)
 {
 #if BITS_PER_LONG == 64
     BUILD_BUG_ON(sizeof(*stats64) < sizeof(*netdev_stats));
     memcpy(stats64, netdev_stats, sizeof(*netdev_stats));
     /* zero out counters that only exist in rtnl_link_stats64 */
     memset((char *)stats64 + sizeof(*netdev_stats), 0,
            sizeof(*stats64) - sizeof(*netdev_stats));
 #else
     size_t i, n = sizeof(*netdev_stats) / sizeof(unsigned long);
     const unsigned long *src = (const unsigned long *)netdev_stats;
     u64 *dst = (u64 *)stats64;
 
     BUILD_BUG_ON(n > sizeof(*stats64) / sizeof(u64));
     for (i = 0; i < n; i++)
         dst[i] = src[i];
     /* zero out counters that only exist in rtnl_link_stats64 */
     memset((char *)stats64 + n * sizeof(u64), 0,
            sizeof(*stats64) - n * sizeof(u64));
 #endif
 }
 EXPORT_SYMBOL(netdev_stats_to_stats64);
 
 struct net_device_core_stats __percpu *netdev_core_stats_alloc(struct net_device *dev)
 {
     struct net_device_core_stats __percpu *p;
 
     p = alloc_percpu_gfp(struct net_device_core_stats,
                  GFP_ATOMIC | __GFP_NOWARN);
 
     if (p && cmpxchg(&dev->core_stats, NULL, p))
         free_percpu(p);
 
     /* This READ_ONCE() pairs with the cmpxchg() above */
     return READ_ONCE(dev->core_stats);
 }
 EXPORT_SYMBOL(netdev_core_stats_alloc);
 
 /**
  *  dev_get_stats   - get network device statistics
  *  @dev: device to get statistics from
  *  @storage: place to store stats
  *
  *  Get network statistics from device. Return @storage.
  *  The device driver may provide its own method by setting
  *  dev->netdev_ops->get_stats64 or dev->netdev_ops->get_stats;
  *  otherwise the internal statistics structure is used.
  */
 struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev,
                     struct rtnl_link_stats64 *storage)
 {
     const struct net_device_ops *ops = dev->netdev_ops;
     const struct net_device_core_stats __percpu *p;
 
     if (ops->ndo_get_stats64) {
         memset(storage, 0, sizeof(*storage));
         ops->ndo_get_stats64(dev, storage);
     } else if (ops->ndo_get_stats) {
         netdev_stats_to_stats64(storage, ops->ndo_get_stats(dev));
     } else {
         netdev_stats_to_stats64(storage, &dev->stats);
     }
 
     /* This READ_ONCE() pairs with the write in netdev_core_stats_alloc() */
     p = READ_ONCE(dev->core_stats);
     if (p) {
         const struct net_device_core_stats *core_stats;
         int i;
 
         for_each_possible_cpu(i) {
             core_stats = per_cpu_ptr(p, i);
             storage->rx_dropped += READ_ONCE(core_stats->rx_dropped);
             storage->tx_dropped += READ_ONCE(core_stats->tx_dropped);
             storage->rx_nohandler += READ_ONCE(core_stats->rx_nohandler);
             storage->rx_otherhost_dropped += READ_ONCE(core_stats->rx_otherhost_dropped);
         }
     }
     return storage;
 }
 EXPORT_SYMBOL(dev_get_stats);
 
 /**
  *  dev_fetch_sw_netstats - get per-cpu network device statistics
  *  @s: place to store stats
  *  @netstats: per-cpu network stats to read from
  *
  *  Read per-cpu network statistics and populate the related fields in @s.
  */
 void dev_fetch_sw_netstats(struct rtnl_link_stats64 *s,
                const struct pcpu_sw_netstats __percpu *netstats)
 {
     int cpu;
 
     for_each_possible_cpu(cpu) {
         u64 rx_packets, rx_bytes, tx_packets, tx_bytes;
         const struct pcpu_sw_netstats *stats;
         unsigned int start;
 
         stats = per_cpu_ptr(netstats, cpu);
         do {
             start = u64_stats_fetch_begin_irq(&stats->syncp);
             rx_packets = u64_stats_read(&stats->rx_packets);
             rx_bytes   = u64_stats_read(&stats->rx_bytes);
             tx_packets = u64_stats_read(&stats->tx_packets);
             tx_bytes   = u64_stats_read(&stats->tx_bytes);
         } while (u64_stats_fetch_retry_irq(&stats->syncp, start));
 
         s->rx_packets += rx_packets;
         s->rx_bytes   += rx_bytes;
         s->tx_packets += tx_packets;
         s->tx_bytes   += tx_bytes;
     }
 }
 EXPORT_SYMBOL_GPL(dev_fetch_sw_netstats);
 
 /**
  *  dev_get_tstats64 - ndo_get_stats64 implementation
  *  @dev: device to get statistics from
  *  @s: place to store stats
  *
  *  Populate @s from dev->stats and dev->tstats. Can be used as
  *  ndo_get_stats64() callback.
  */
 void dev_get_tstats64(struct net_device *dev, struct rtnl_link_stats64 *s)
 {
     netdev_stats_to_stats64(s, &dev->stats);
     dev_fetch_sw_netstats(s, dev->tstats);
 }
 EXPORT_SYMBOL_GPL(dev_get_tstats64);
 
 struct netdev_queue *dev_ingress_queue_create(struct net_device *dev)
 {
     struct netdev_queue *queue = dev_ingress_queue(dev);
 
 #ifdef CONFIG_NET_CLS_ACT
     if (queue)
         return queue;
     queue = kzalloc(sizeof(*queue), GFP_KERNEL);
     if (!queue)
         return NULL;
     netdev_init_one_queue(dev, queue, NULL);
     RCU_INIT_POINTER(queue->qdisc, &noop_qdisc);
     queue->qdisc_sleeping = &noop_qdisc;
     rcu_assign_pointer(dev->ingress_queue, queue);
 #endif
     return queue;
 }
 
 static const struct ethtool_ops default_ethtool_ops;
 
 void netdev_set_default_ethtool_ops(struct net_device *dev,
                     const struct ethtool_ops *ops)
 {
     if (dev->ethtool_ops == &default_ethtool_ops)
         dev->ethtool_ops = ops;
 }
 EXPORT_SYMBOL_GPL(netdev_set_default_ethtool_ops);
 
 void netdev_freemem(struct net_device *dev)
 {
     char *addr = (char *)dev - dev->padded;
 
     kvfree(addr);
 }
 
 /**
  * alloc_netdev_mqs - allocate network device
  * @sizeof_priv: size of private data to allocate space for
  * @name: device name format string
  * @name_assign_type: origin of device name
  * @setup: callback to initialize device
  * @txqs: the number of TX subqueues to allocate
  * @rxqs: the number of RX subqueues to allocate
  *
  * Allocates a struct net_device with private data area for driver use
  * and performs basic initialization.  Also allocates subqueue structs
  * for each queue on the device.
  */
 struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
         unsigned char name_assign_type,
         void (*setup)(struct net_device *),
         unsigned int txqs, unsigned int rxqs)
 {
     struct net_device *dev;
     unsigned int alloc_size;
     struct net_device *p;
 
     BUG_ON(strlen(name) >= sizeof(dev->name));
 
     if (txqs < 1) {
         pr_err("alloc_netdev: Unable to allocate device with zero queues\n");
         return NULL;
     }
 
     if (rxqs < 1) {
         pr_err("alloc_netdev: Unable to allocate device with zero RX queues\n");
         return NULL;
     }
 
     alloc_size = sizeof(struct net_device);
     if (sizeof_priv) {
         /* ensure 32-byte alignment of private area */
         alloc_size = ALIGN(alloc_size, NETDEV_ALIGN);
         alloc_size += sizeof_priv;
     }
     /* ensure 32-byte alignment of whole construct */
     alloc_size += NETDEV_ALIGN - 1;
 
     p = kvzalloc(alloc_size, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
     if (!p)
         return NULL;
 
     dev = PTR_ALIGN(p, NETDEV_ALIGN);
     dev->padded = (char *)dev - (char *)p;
 
     ref_tracker_dir_init(&dev->refcnt_tracker, 128);
 #ifdef CONFIG_PCPU_DEV_REFCNT
     dev->pcpu_refcnt = alloc_percpu(int);
     if (!dev->pcpu_refcnt)
         goto free_dev;
     __dev_hold(dev);
 #else
     refcount_set(&dev->dev_refcnt, 1);
 #endif
 
     if (dev_addr_init(dev))
         goto free_pcpu;
 
     dev_mc_init(dev);
     dev_uc_init(dev);
 
     dev_net_set(dev, &init_net);
 
     dev->gso_max_size = GSO_LEGACY_MAX_SIZE;
     dev->gso_max_segs = GSO_MAX_SEGS;
     dev->gro_max_size = GRO_LEGACY_MAX_SIZE;
     dev->tso_max_size = TSO_LEGACY_MAX_SIZE;
     dev->tso_max_segs = TSO_MAX_SEGS;
     dev->upper_level = 1;
     dev->lower_level = 1;
 #ifdef CONFIG_LOCKDEP
     dev->nested_level = 0;
     INIT_LIST_HEAD(&dev->unlink_list);
 #endif
 
     INIT_LIST_HEAD(&dev->napi_list);
     INIT_LIST_HEAD(&dev->unreg_list);
     INIT_LIST_HEAD(&dev->close_list);
     INIT_LIST_HEAD(&dev->link_watch_list);
     INIT_LIST_HEAD(&dev->adj_list.upper);
     INIT_LIST_HEAD(&dev->adj_list.lower);
     INIT_LIST_HEAD(&dev->ptype_all);
     INIT_LIST_HEAD(&dev->ptype_specific);
     INIT_LIST_HEAD(&dev->net_notifier_list);
 #ifdef CONFIG_NET_SCHED
     hash_init(dev->qdisc_hash);
 #endif
     dev->priv_flags = IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM;
     setup(dev);
 
     if (!dev->tx_queue_len) {
         dev->priv_flags |= IFF_NO_QUEUE;
         dev->tx_queue_len = DEFAULT_TX_QUEUE_LEN;
     }
 
     dev->num_tx_queues = txqs;
     dev->real_num_tx_queues = txqs;
     if (netif_alloc_netdev_queues(dev))
         goto free_all;
 
     dev->num_rx_queues = rxqs;
     dev->real_num_rx_queues = rxqs;
     if (netif_alloc_rx_queues(dev))
         goto free_all;
 
     strcpy(dev->name, name);
     dev->name_assign_type = name_assign_type;
     dev->group = INIT_NETDEV_GROUP;
     if (!dev->ethtool_ops)
         dev->ethtool_ops = &default_ethtool_ops;
 
     nf_hook_netdev_init(dev);
 
     return dev;
 
 free_all:
     free_netdev(dev);
     return NULL;
 
 free_pcpu:
 #ifdef CONFIG_PCPU_DEV_REFCNT
     free_percpu(dev->pcpu_refcnt);
 free_dev:
 #endif
     netdev_freemem(dev);
     return NULL;
 }
 EXPORT_SYMBOL(alloc_netdev_mqs);
 
 /**
  * free_netdev - free network device
  * @dev: device
  *
  * This function does the last stage of destroying an allocated device
  * interface. The reference to the device object is released. If this
  * is the last reference then it will be freed.Must be called in process
  * context.
  */
 void free_netdev(struct net_device *dev)
 {
     struct napi_struct *p, *n;
 
     might_sleep();
 
     /* When called immediately after register_netdevice() failed the unwind
      * handling may still be dismantling the device. Handle that case by
      * deferring the free.
      */
     if (dev->reg_state == NETREG_UNREGISTERING) {
         ASSERT_RTNL();
         dev->needs_free_netdev = true;
         return;
     }
 
     netif_free_tx_queues(dev);
     netif_free_rx_queues(dev);
 
     kfree(rcu_dereference_protected(dev->ingress_queue, 1));
 
     /* Flush device addresses */
     dev_addr_flush(dev);
 
     list_for_each_entry_safe(p, n, &dev->napi_list, dev_list)
         netif_napi_del(p);
 
     ref_tracker_dir_exit(&dev->refcnt_tracker);
 #ifdef CONFIG_PCPU_DEV_REFCNT
     free_percpu(dev->pcpu_refcnt);
     dev->pcpu_refcnt = NULL;
 #endif
     free_percpu(dev->core_stats);
     dev->core_stats = NULL;
     free_percpu(dev->xdp_bulkq);
     dev->xdp_bulkq = NULL;
 
     /*  Compatibility with error handling in drivers */
     if (dev->reg_state == NETREG_UNINITIALIZED) {
         netdev_freemem(dev);
         return;
     }
 
     BUG_ON(dev->reg_state != NETREG_UNREGISTERED);
     dev->reg_state = NETREG_RELEASED;
 
     /* will free via device release */
     put_device(&dev->dev);
 }
 EXPORT_SYMBOL(free_netdev);
 
 /**
  *  synchronize_net -  Synchronize with packet receive processing
  *
  *  Wait for packets currently being received to be done.
  *  Does not block later packets from starting.
  */
 void synchronize_net(void)
 {
     might_sleep();
     if (rtnl_is_locked())
         synchronize_rcu_expedited();
     else
         synchronize_rcu();
 }
 EXPORT_SYMBOL(synchronize_net);
 
 /**
  *  unregister_netdevice_queue - remove device from the kernel
  *  @dev: device
  *  @head: list
  *
  *  This function shuts down a device interface and removes it
  *  from the kernel tables.
  *  If head not NULL, device is queued to be unregistered later.
  *
  *  Callers must hold the rtnl semaphore.  You may want
  *  unregister_netdev() instead of this.
  */
 
 void unregister_netdevice_queue(struct net_device *dev, struct list_head *head)
 {
     ASSERT_RTNL();
 
     if (head) {
         list_move_tail(&dev->unreg_list, head);
     } else {
         LIST_HEAD(single);
 
         list_add(&dev->unreg_list, &single);
         unregister_netdevice_many(&single);
     }
 }
 EXPORT_SYMBOL(unregister_netdevice_queue);
 
 /**
  *  unregister_netdevice_many - unregister many devices
  *  @head: list of devices
  *
  *  Note: As most callers use a stack allocated list_head,
  *  we force a list_del() to make sure stack wont be corrupted later.
  */
 void unregister_netdevice_many(struct list_head *head)
 {
     struct net_device *dev, *tmp;
     LIST_HEAD(close_head);
 
     BUG_ON(dev_boot_phase);
     ASSERT_RTNL();
 
     if (list_empty(head))
         return;
 
     list_for_each_entry_safe(dev, tmp, head, unreg_list) {
         /* Some devices call without registering
          * for initialization unwind. Remove those
          * devices and proceed with the remaining.
          */
         if (dev->reg_state == NETREG_UNINITIALIZED) {
             pr_debug("unregister_netdevice: device %s/%p never was registered\n",
                  dev->name, dev);
 
             WARN_ON(1);
             list_del(&dev->unreg_list);
             continue;
         }
         dev->dismantle = true;
         BUG_ON(dev->reg_state != NETREG_REGISTERED);
     }
 
     /* If device is running, close it first. */
     list_for_each_entry(dev, head, unreg_list)
         list_add_tail(&dev->close_list, &close_head);
     dev_close_many(&close_head, true);
 
     list_for_each_entry(dev, head, unreg_list) {
         /* And unlink it from device chain. */
         write_lock(&dev_base_lock);
         unlist_netdevice(dev, false);
         dev->reg_state = NETREG_UNREGISTERING;
         write_unlock(&dev_base_lock);
     }
     flush_all_backlogs();
 
     synchronize_net();
 
     list_for_each_entry(dev, head, unreg_list) {
         struct sk_buff *skb = NULL;
 
         /* Shutdown queueing discipline. */
         dev_shutdown(dev);
 
         dev_xdp_uninstall(dev);
 
         netdev_offload_xstats_disable_all(dev);
 
         /* Notify protocols, that we are about to destroy
          * this device. They should clean all the things.
          */
         call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
 
         if (!dev->rtnl_link_ops ||
             dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
             skb = rtmsg_ifinfo_build_skb(RTM_DELLINK, dev, ~0U, 0,
                              GFP_KERNEL, NULL, 0);
 
         /*
          *  Flush the unicast and multicast chains
          */
         dev_uc_flush(dev);
         dev_mc_flush(dev);
 
         netdev_name_node_alt_flush(dev);
         netdev_name_node_free(dev->name_node);
 
         if (dev->netdev_ops->ndo_uninit)
             dev->netdev_ops->ndo_uninit(dev);
 
         if (skb)
             rtmsg_ifinfo_send(skb, dev, GFP_KERNEL);
 
         /* Notifier chain MUST detach us all upper devices. */
         WARN_ON(netdev_has_any_upper_dev(dev));
         WARN_ON(netdev_has_any_lower_dev(dev));
 
         /* Remove entries from kobject tree */
         netdev_unregister_kobject(dev);
 #ifdef CONFIG_XPS
         /* Remove XPS queueing entries */
         netif_reset_xps_queues_gt(dev, 0);
 #endif
     }
 
     synchronize_net();
 
     list_for_each_entry(dev, head, unreg_list) {
         netdev_put(dev, &dev->dev_registered_tracker);
         net_set_todo(dev);
     }
 
     list_del(head);
 }
 EXPORT_SYMBOL(unregister_netdevice_many);
 
 /**
  *  unregister_netdev - remove device from the kernel
  *  @dev: device
  *
  *  This function shuts down a device interface and removes it
  *  from the kernel tables.
  *
  *  This is just a wrapper for unregister_netdevice that takes
  *  the rtnl semaphore.  In general you want to use this and not
  *  unregister_netdevice.
  */
 void unregister_netdev(struct net_device *dev)
 {
     rtnl_lock();
     unregister_netdevice(dev);
     rtnl_unlock();
 }
 EXPORT_SYMBOL(unregister_netdev);
 
 /**
  *  __dev_change_net_namespace - move device to different nethost namespace
  *  @dev: device
  *  @net: network namespace
  *  @pat: If not NULL name pattern to try if the current device name
  *        is already taken in the destination network namespace.
  *  @new_ifindex: If not zero, specifies device index in the target
  *                namespace.
  *
  *  This function shuts down a device interface and moves it
  *  to a new network namespace. On success 0 is returned, on
  *  a failure a netagive errno code is returned.
  *
  *  Callers must hold the rtnl semaphore.
  */
 
 int __dev_change_net_namespace(struct net_device *dev, struct net *net,
                    const char *pat, int new_ifindex)
 {
     struct net *net_old = dev_net(dev);
     int err, new_nsid;
 
     ASSERT_RTNL();
 
     /* Don't allow namespace local devices to be moved. */
     err = -EINVAL;
     if (dev->features & NETIF_F_NETNS_LOCAL)
         goto out;
 
     /* Ensure the device has been registrered */
     if (dev->reg_state != NETREG_REGISTERED)
         goto out;
 
     /* Get out if there is nothing todo */
     err = 0;
     if (net_eq(net_old, net))
         goto out;
 
     /* Pick the destination device name, and ensure
      * we can use it in the destination network namespace.
      */
     err = -EEXIST;
     if (netdev_name_in_use(net, dev->name)) {
         /* We get here if we can't use the current device name */
         if (!pat)
             goto out;
         err = dev_get_valid_name(net, dev, pat);
         if (err < 0)
             goto out;
     }
 
     /* Check that new_ifindex isn't used yet. */
     err = -EBUSY;
     if (new_ifindex && __dev_get_by_index(net, new_ifindex))
         goto out;
 
     /*
      * And now a mini version of register_netdevice unregister_netdevice.
      */
 
     /* If device is running close it first. */
     dev_close(dev);
 
     /* And unlink it from device chain */
     unlist_netdevice(dev, true);
 
     synchronize_net();
 
     /* Shutdown queueing discipline. */
     dev_shutdown(dev);
 
     /* Notify protocols, that we are about to destroy
      * this device. They should clean all the things.
      *
      * Note that dev->reg_state stays at NETREG_REGISTERED.
      * This is wanted because this way 8021q and macvlan know
      * the device is just moving and can keep their slaves up.
      */
     call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
     rcu_barrier();
 
     new_nsid = peernet2id_alloc(dev_net(dev), net, GFP_KERNEL);
     /* If there is an ifindex conflict assign a new one */
     if (!new_ifindex) {
         if (__dev_get_by_index(net, dev->ifindex))
             new_ifindex = dev_new_index(net);
         else
             new_ifindex = dev->ifindex;
     }
 
     rtmsg_ifinfo_newnet(RTM_DELLINK, dev, ~0U, GFP_KERNEL, &new_nsid,
                 new_ifindex);
 
     /*
      *  Flush the unicast and multicast chains
      */
     dev_uc_flush(dev);
     dev_mc_flush(dev);
 
     /* Send a netdev-removed uevent to the old namespace */
     kobject_uevent(&dev->dev.kobj, KOBJ_REMOVE);
     netdev_adjacent_del_links(dev);
 
     /* Move per-net netdevice notifiers that are following the netdevice */
     move_netdevice_notifiers_dev_net(dev, net);
 
     /* Actually switch the network namespace */
     dev_net_set(dev, net);
     dev->ifindex = new_ifindex;
 
     /* Send a netdev-add uevent to the new namespace */
     kobject_uevent(&dev->dev.kobj, KOBJ_ADD);
     netdev_adjacent_add_links(dev);
 
     /* Fixup kobjects */
     err = device_rename(&dev->dev, dev->name);
     WARN_ON(err);
 
     /* Adapt owner in case owning user namespace of target network
      * namespace is different from the original one.
      */
     err = netdev_change_owner(dev, net_old, net);
     WARN_ON(err);
 
     /* Add the device back in the hashes */
     list_netdevice(dev);
 
     /* Notify protocols, that a new device appeared. */
     call_netdevice_notifiers(NETDEV_REGISTER, dev);
 
     /*
      *  Prevent userspace races by waiting until the network
      *  device is fully setup before sending notifications.
      */
     rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL);
 
     synchronize_net();
     err = 0;
 out:
     return err;
 }
 EXPORT_SYMBOL_GPL(__dev_change_net_namespace);
 
 static int dev_cpu_dead(unsigned int oldcpu)
 {
     struct sk_buff **list_skb;
     struct sk_buff *skb;
     unsigned int cpu;
     struct softnet_data *sd, *oldsd, *remsd = NULL;
 
     local_irq_disable();
     cpu = smp_processor_id();
     sd = &per_cpu(softnet_data, cpu);
     oldsd = &per_cpu(softnet_data, oldcpu);
 
     /* Find end of our completion_queue. */
     list_skb = &sd->completion_queue;
     while (*list_skb)
         list_skb = &(*list_skb)->next;
     /* Append completion queue from offline CPU. */
     *list_skb = oldsd->completion_queue;
     oldsd->completion_queue = NULL;
 
     /* Append output queue from offline CPU. */
     if (oldsd->output_queue) {
         *sd->output_queue_tailp = oldsd->output_queue;
         sd->output_queue_tailp = oldsd->output_queue_tailp;
         oldsd->output_queue = NULL;
         oldsd->output_queue_tailp = &oldsd->output_queue;
     }
     /* Append NAPI poll list from offline CPU, with one exception :
      * process_backlog() must be called by cpu owning percpu backlog.
      * We properly handle process_queue & input_pkt_queue later.
      */
     while (!list_empty(&oldsd->poll_list)) {
         struct napi_struct *napi = list_first_entry(&oldsd->poll_list,
                                 struct napi_struct,
                                 poll_list);
 
         list_del_init(&napi->poll_list);
         if (napi->poll == process_backlog)
             napi->state = 0;
         else
             ____napi_schedule(sd, napi);
     }
 
     raise_softirq_irqoff(NET_TX_SOFTIRQ);
     local_irq_enable();
 
 #ifdef CONFIG_RPS
     remsd = oldsd->rps_ipi_list;
     oldsd->rps_ipi_list = NULL;
 #endif
     /* send out pending IPI's on offline CPU */
     net_rps_send_ipi(remsd);
 
     /* Process offline CPU's input_pkt_queue */
     while ((skb = __skb_dequeue(&oldsd->process_queue))) {
         netif_rx(skb);
         input_queue_head_incr(oldsd);
     }
     while ((skb = skb_dequeue(&oldsd->input_pkt_queue))) {
         netif_rx(skb);
         input_queue_head_incr(oldsd);
     }
 
     return 0;
 }
 
 /**
  *  netdev_increment_features - increment feature set by one
  *  @all: current feature set
  *  @one: new feature set
  *  @mask: mask feature set
  *
  *  Computes a new feature set after adding a device with feature set
  *  @one to the master device with current feature set @all.  Will not
  *  enable anything that is off in @mask. Returns the new feature set.
  */
 netdev_features_t netdev_increment_features(netdev_features_t all,
     netdev_features_t one, netdev_features_t mask)
 {
     if (mask & NETIF_F_HW_CSUM)
         mask |= NETIF_F_CSUM_MASK;
     mask |= NETIF_F_VLAN_CHALLENGED;
 
     all |= one & (NETIF_F_ONE_FOR_ALL | NETIF_F_CSUM_MASK) & mask;
     all &= one | ~NETIF_F_ALL_FOR_ALL;
 
     /* If one device supports hw checksumming, set for all. */
     if (all & NETIF_F_HW_CSUM)
         all &= ~(NETIF_F_CSUM_MASK & ~NETIF_F_HW_CSUM);
 
     return all;
 }
 EXPORT_SYMBOL(netdev_increment_features);
 
 static struct hlist_head * __net_init netdev_create_hash(void)
 {
     int i;
     struct hlist_head *hash;
 
     hash = kmalloc_array(NETDEV_HASHENTRIES, sizeof(*hash), GFP_KERNEL);
     if (hash != NULL)
         for (i = 0; i < NETDEV_HASHENTRIES; i++)
             INIT_HLIST_HEAD(&hash[i]);
 
     return hash;
 }
 
 /* Initialize per network namespace state */
 static int __net_init netdev_init(struct net *net)
 {
     BUILD_BUG_ON(GRO_HASH_BUCKETS >
              8 * sizeof_field(struct napi_struct, gro_bitmask));
 
     INIT_LIST_HEAD(&net->dev_base_head);
 
     net->dev_name_head = netdev_create_hash();
     if (net->dev_name_head == NULL)
         goto err_name;
 
     net->dev_index_head = netdev_create_hash();
     if (net->dev_index_head == NULL)
         goto err_idx;
 
     RAW_INIT_NOTIFIER_HEAD(&net->netdev_chain);
 
     return 0;
 
 err_idx:
     kfree(net->dev_name_head);
 err_name:
     return -ENOMEM;
 }
 
 /**
  *  netdev_drivername - network driver for the device
  *  @dev: network device
  *
  *  Determine network driver for device.
  */
 const char *netdev_drivername(const struct net_device *dev)
 {
     const struct device_driver *driver;
     const struct device *parent;
     const char *empty = "";
 
     parent = dev->dev.parent;
     if (!parent)
         return empty;
 
     driver = parent->driver;
     if (driver && driver->name)
         return driver->name;
     return empty;
 }
 
 static void __netdev_printk(const char *level, const struct net_device *dev,
                 struct va_format *vaf)
 {
     if (dev && dev->dev.parent) {
         dev_printk_emit(level[1] - '0',
                 dev->dev.parent,
                 "%s %s %s%s: %pV",
                 dev_driver_string(dev->dev.parent),
                 dev_name(dev->dev.parent),
                 netdev_name(dev), netdev_reg_state(dev),
                 vaf);
     } else if (dev) {
         printk("%s%s%s: %pV",
                level, netdev_name(dev), netdev_reg_state(dev), vaf);
     } else {
         printk("%s(NULL net_device): %pV", level, vaf);
     }
 }
 
 void netdev_printk(const char *level, const struct net_device *dev,
            const char *format, ...)
 {
     struct va_format vaf;
     va_list args;
 
     va_start(args, format);
 
     vaf.fmt = format;
     vaf.va = &args;
 
     __netdev_printk(level, dev, &vaf);
 
     va_end(args);
 }
 EXPORT_SYMBOL(netdev_printk);
 
 #define define_netdev_printk_level(func, level)         \
 void func(const struct net_device *dev, const char *fmt, ...)   \
 {                               \
     struct va_format vaf;                   \
     va_list args;                       \
                                 \
     va_start(args, fmt);                    \
                                 \
     vaf.fmt = fmt;                      \
     vaf.va = &args;                     \
                                 \
     __netdev_printk(level, dev, &vaf);          \
                                 \
     va_end(args);                       \
 }                               \
 EXPORT_SYMBOL(func);
 
 define_netdev_printk_level(netdev_emerg, KERN_EMERG);
 define_netdev_printk_level(netdev_alert, KERN_ALERT);
 define_netdev_printk_level(netdev_crit, KERN_CRIT);
 define_netdev_printk_level(netdev_err, KERN_ERR);
 define_netdev_printk_level(netdev_warn, KERN_WARNING);
 define_netdev_printk_level(netdev_notice, KERN_NOTICE);
 define_netdev_printk_level(netdev_info, KERN_INFO);
 
 static void __net_exit netdev_exit(struct net *net)
 {
     kfree(net->dev_name_head);
     kfree(net->dev_index_head);
     if (net != &init_net)
         WARN_ON_ONCE(!list_empty(&net->dev_base_head));
 }
 
 static struct pernet_operations __net_initdata netdev_net_ops = {
     .init = netdev_init,
     .exit = netdev_exit,
 };
 
 static void __net_exit default_device_exit_net(struct net *net)
 {
     struct net_device *dev, *aux;
     /*
      * Push all migratable network devices back to the
      * initial network namespace
      */
     ASSERT_RTNL();
     for_each_netdev_safe(net, dev, aux) {
         int err;
         char fb_name[IFNAMSIZ];
 
         /* Ignore unmoveable devices (i.e. loopback) */
         if (dev->features & NETIF_F_NETNS_LOCAL)
             continue;
 
         /* Leave virtual devices for the generic cleanup */
         if (dev->rtnl_link_ops && !dev->rtnl_link_ops->netns_refund)
             continue;
 
         /* Push remaining network devices to init_net */
         snprintf(fb_name, IFNAMSIZ, "dev%d", dev->ifindex);
         if (netdev_name_in_use(&init_net, fb_name))
             snprintf(fb_name, IFNAMSIZ, "dev%%d");
         err = dev_change_net_namespace(dev, &init_net, fb_name);
         if (err) {
             pr_emerg("%s: failed to move %s to init_net: %d\n",
                  __func__, dev->name, err);
             BUG();
         }
     }
 }
 
 static void __net_exit default_device_exit_batch(struct list_head *net_list)
 {
     /* At exit all network devices most be removed from a network
      * namespace.  Do this in the reverse order of registration.
      * Do this across as many network namespaces as possible to
      * improve batching efficiency.
      */
     struct net_device *dev;
     struct net *net;
     LIST_HEAD(dev_kill_list);
 
     rtnl_lock();
     list_for_each_entry(net, net_list, exit_list) {
         default_device_exit_net(net);
         cond_resched();
     }
 
     list_for_each_entry(net, net_list, exit_list) {
         for_each_netdev_reverse(net, dev) {
             if (dev->rtnl_link_ops && dev->rtnl_link_ops->dellink)
                 dev->rtnl_link_ops->dellink(dev, &dev_kill_list);
             else
                 unregister_netdevice_queue(dev, &dev_kill_list);
         }
     }
     unregister_netdevice_many(&dev_kill_list);
     rtnl_unlock();
 }
 
 static struct pernet_operations __net_initdata default_device_ops = {
     .exit_batch = default_device_exit_batch,
 };
 
 /*
  *  Initialize the DEV module. At boot time this walks the device list and
  *  unhooks any devices that fail to initialise (normally hardware not
  *  present) and leaves us with a valid list of present and active devices.
  *
  */
 
 /*
  *       This is called single threaded during boot, so no need
  *       to take the rtnl semaphore.
  */
 static int __init net_dev_init(void)
 {
     int i, rc = -ENOMEM;
 
     BUG_ON(!dev_boot_phase);
 
     if (dev_proc_init())
         goto out;
 
     if (netdev_kobject_init())
         goto out;
 
     INIT_LIST_HEAD(&ptype_all);
     for (i = 0; i < PTYPE_HASH_SIZE; i++)
         INIT_LIST_HEAD(&ptype_base[i]);
 
     if (register_pernet_subsys(&netdev_net_ops))
         goto out;
 
     /*
      *  Initialise the packet receive queues.
      */
 
     for_each_possible_cpu(i) {
         struct work_struct *flush = per_cpu_ptr(&flush_works, i);
         struct softnet_data *sd = &per_cpu(softnet_data, i);
 
         INIT_WORK(flush, flush_backlog);
 
         skb_queue_head_init(&sd->input_pkt_queue);
         skb_queue_head_init(&sd->process_queue);
 #ifdef CONFIG_XFRM_OFFLOAD
         skb_queue_head_init(&sd->xfrm_backlog);
 #endif
         INIT_LIST_HEAD(&sd->poll_list);
         sd->output_queue_tailp = &sd->output_queue;
 #ifdef CONFIG_RPS
         INIT_CSD(&sd->csd, rps_trigger_softirq, sd);
         sd->cpu = i;
 #endif
         INIT_CSD(&sd->defer_csd, trigger_rx_softirq, sd);
         spin_lock_init(&sd->defer_lock);
 
         init_gro_hash(&sd->backlog);
         sd->backlog.poll = process_backlog;
         sd->backlog.weight = weight_p;
     }
 
     dev_boot_phase = 0;
 
     /* The loopback device is special if any other network devices
      * is present in a network namespace the loopback device must
      * be present. Since we now dynamically allocate and free the
      * loopback device ensure this invariant is maintained by
      * keeping the loopback device as the first device on the
      * list of network devices.  Ensuring the loopback devices
      * is the first device that appears and the last network device
      * that disappears.
      */
     if (register_pernet_device(&loopback_net_ops))
         goto out;
 
     if (register_pernet_device(&default_device_ops))
         goto out;
 
     open_softirq(NET_TX_SOFTIRQ, net_tx_action);
     open_softirq(NET_RX_SOFTIRQ, net_rx_action);
 
     rc = cpuhp_setup_state_nocalls(CPUHP_NET_DEV_DEAD, "net/dev:dead",
                        NULL, dev_cpu_dead);
     WARN_ON(rc < 0);
     rc = 0;
 out:
     return rc;
 }
 
 subsys_initcall(net_dev_init);