OSCL-LXR linux-6.0.1/​net/​batman-adv/​hard-interface.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
 /* Copyright (C) B.A.T.M.A.N. contributors:
  *
  * Marek Lindner, Simon Wunderlich
  */
 
 #include "hard-interface.h"
 #include "main.h"
 
 #include <linux/atomic.h>
 #include <linux/byteorder/generic.h>
 #include <linux/container_of.h>
 #include <linux/errno.h>
 #include <linux/gfp.h>
 #include <linux/if.h>
 #include <linux/if_arp.h>
 #include <linux/if_ether.h>
 #include <linux/kref.h>
 #include <linux/limits.h>
 #include <linux/list.h>
 #include <linux/minmax.h>
 #include <linux/mutex.h>
 #include <linux/netdevice.h>
 #include <linux/printk.h>
 #include <linux/rculist.h>
 #include <linux/rtnetlink.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <net/net_namespace.h>
 #include <net/rtnetlink.h>
 #include <uapi/linux/batadv_packet.h>
 
 #include "bat_v.h"
 #include "bridge_loop_avoidance.h"
 #include "distributed-arp-table.h"
 #include "gateway_client.h"
 #include "log.h"
 #include "originator.h"
 #include "send.h"
 #include "soft-interface.h"
 #include "translation-table.h"
 
 /**
  * batadv_hardif_release() - release hard interface from lists and queue for
  *  free after rcu grace period
  * @ref: kref pointer of the hard interface
  */
 void batadv_hardif_release(struct kref *ref)
 {
     struct batadv_hard_iface *hard_iface;
 
     hard_iface = container_of(ref, struct batadv_hard_iface, refcount);
     dev_put(hard_iface->net_dev);
 
     kfree_rcu(hard_iface, rcu);
 }
 
 /**
  * batadv_hardif_get_by_netdev() - Get hard interface object of a net_device
  * @net_dev: net_device to search for
  *
  * Return: batadv_hard_iface of net_dev (with increased refcnt), NULL on errors
  */
 struct batadv_hard_iface *
 batadv_hardif_get_by_netdev(const struct net_device *net_dev)
 {
     struct batadv_hard_iface *hard_iface;
 
     rcu_read_lock();
     list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
         if (hard_iface->net_dev == net_dev &&
             kref_get_unless_zero(&hard_iface->refcount))
             goto out;
     }
 
     hard_iface = NULL;
 
 out:
     rcu_read_unlock();
     return hard_iface;
 }
 
 /**
  * batadv_getlink_net() - return link net namespace (of use fallback)
  * @netdev: net_device to check
  * @fallback_net: return in case get_link_net is not available for @netdev
  *
  * Return: result of rtnl_link_ops->get_link_net or @fallback_net
  */
 static struct net *batadv_getlink_net(const struct net_device *netdev,
                       struct net *fallback_net)
 {
     if (!netdev->rtnl_link_ops)
         return fallback_net;
 
     if (!netdev->rtnl_link_ops->get_link_net)
         return fallback_net;
 
     return netdev->rtnl_link_ops->get_link_net(netdev);
 }
 
 /**
  * batadv_mutual_parents() - check if two devices are each others parent
  * @dev1: 1st net dev
  * @net1: 1st devices netns
  * @dev2: 2nd net dev
  * @net2: 2nd devices netns
  *
  * veth devices come in pairs and each is the parent of the other!
  *
  * Return: true if the devices are each others parent, otherwise false
  */
 static bool batadv_mutual_parents(const struct net_device *dev1,
                   struct net *net1,
                   const struct net_device *dev2,
                   struct net *net2)
 {
     int dev1_parent_iflink = dev_get_iflink(dev1);
     int dev2_parent_iflink = dev_get_iflink(dev2);
     const struct net *dev1_parent_net;
     const struct net *dev2_parent_net;
 
     dev1_parent_net = batadv_getlink_net(dev1, net1);
     dev2_parent_net = batadv_getlink_net(dev2, net2);
 
     if (!dev1_parent_iflink || !dev2_parent_iflink)
         return false;
 
     return (dev1_parent_iflink == dev2->ifindex) &&
            (dev2_parent_iflink == dev1->ifindex) &&
            net_eq(dev1_parent_net, net2) &&
            net_eq(dev2_parent_net, net1);
 }
 
 /**
  * batadv_is_on_batman_iface() - check if a device is a batman iface descendant
  * @net_dev: the device to check
  *
  * If the user creates any virtual device on top of a batman-adv interface, it
  * is important to prevent this new interface from being used to create a new
  * mesh network (this behaviour would lead to a batman-over-batman
  * configuration). This function recursively checks all the fathers of the
  * device passed as argument looking for a batman-adv soft interface.
  *
  * Return: true if the device is descendant of a batman-adv mesh interface (or
  * if it is a batman-adv interface itself), false otherwise
  */
 static bool batadv_is_on_batman_iface(const struct net_device *net_dev)
 {
     struct net *net = dev_net(net_dev);
     struct net_device *parent_dev;
     struct net *parent_net;
     int iflink;
     bool ret;
 
     /* check if this is a batman-adv mesh interface */
     if (batadv_softif_is_valid(net_dev))
         return true;
 
     iflink = dev_get_iflink(net_dev);
     if (iflink == 0)
         return false;
 
     parent_net = batadv_getlink_net(net_dev, net);
 
     /* iflink to itself, most likely physical device */
     if (net == parent_net && iflink == net_dev->ifindex)
         return false;
 
     /* recurse over the parent device */
     parent_dev = __dev_get_by_index((struct net *)parent_net, iflink);
     if (!parent_dev) {
         pr_warn("Cannot find parent device. Skipping batadv-on-batadv check for %s\n",
             net_dev->name);
         return false;
     }
 
     if (batadv_mutual_parents(net_dev, net, parent_dev, parent_net))
         return false;
 
     ret = batadv_is_on_batman_iface(parent_dev);
 
     return ret;
 }
 
 static bool batadv_is_valid_iface(const struct net_device *net_dev)
 {
     if (net_dev->flags & IFF_LOOPBACK)
         return false;
 
     if (net_dev->type != ARPHRD_ETHER)
         return false;
 
     if (net_dev->addr_len != ETH_ALEN)
         return false;
 
     /* no batman over batman */
     if (batadv_is_on_batman_iface(net_dev))
         return false;
 
     return true;
 }
 
 /**
  * batadv_get_real_netdevice() - check if the given netdev struct is a virtual
  *  interface on top of another 'real' interface
  * @netdev: the device to check
  *
  * Callers must hold the rtnl semaphore. You may want batadv_get_real_netdev()
  * instead of this.
  *
  * Return: the 'real' net device or the original net device and NULL in case
  *  of an error.
  */
 static struct net_device *batadv_get_real_netdevice(struct net_device *netdev)
 {
     struct batadv_hard_iface *hard_iface = NULL;
     struct net_device *real_netdev = NULL;
     struct net *real_net;
     struct net *net;
     int iflink;
 
     ASSERT_RTNL();
 
     if (!netdev)
         return NULL;
 
     iflink = dev_get_iflink(netdev);
     if (iflink == 0) {
         dev_hold(netdev);
         return netdev;
     }
 
     hard_iface = batadv_hardif_get_by_netdev(netdev);
     if (!hard_iface || !hard_iface->soft_iface)
         goto out;
 
     net = dev_net(hard_iface->soft_iface);
     real_net = batadv_getlink_net(netdev, net);
 
     /* iflink to itself, most likely physical device */
     if (net == real_net && netdev->ifindex == iflink) {
         real_netdev = netdev;
         dev_hold(real_netdev);
         goto out;
     }
 
     real_netdev = dev_get_by_index(real_net, iflink);
 
 out:
     batadv_hardif_put(hard_iface);
     return real_netdev;
 }
 
 /**
  * batadv_get_real_netdev() - check if the given net_device struct is a virtual
  *  interface on top of another 'real' interface
  * @net_device: the device to check
  *
  * Return: the 'real' net device or the original net device and NULL in case
  *  of an error.
  */
 struct net_device *batadv_get_real_netdev(struct net_device *net_device)
 {
     struct net_device *real_netdev;
 
     rtnl_lock();
     real_netdev = batadv_get_real_netdevice(net_device);
     rtnl_unlock();
 
     return real_netdev;
 }
 
 /**
  * batadv_is_wext_netdev() - check if the given net_device struct is a
  *  wext wifi interface
  * @net_device: the device to check
  *
  * Return: true if the net device is a wext wireless device, false
  *  otherwise.
  */
 static bool batadv_is_wext_netdev(struct net_device *net_device)
 {
     if (!net_device)
         return false;
 
 #ifdef CONFIG_WIRELESS_EXT
     /* pre-cfg80211 drivers have to implement WEXT, so it is possible to
      * check for wireless_handlers != NULL
      */
     if (net_device->wireless_handlers)
         return true;
 #endif
 
     return false;
 }
 
 /**
  * batadv_is_cfg80211_netdev() - check if the given net_device struct is a
  *  cfg80211 wifi interface
  * @net_device: the device to check
  *
  * Return: true if the net device is a cfg80211 wireless device, false
  *  otherwise.
  */
 static bool batadv_is_cfg80211_netdev(struct net_device *net_device)
 {
     if (!net_device)
         return false;
 
 #if IS_ENABLED(CONFIG_CFG80211)
     /* cfg80211 drivers have to set ieee80211_ptr */
     if (net_device->ieee80211_ptr)
         return true;
 #endif
 
     return false;
 }
 
 /**
  * batadv_wifi_flags_evaluate() - calculate wifi flags for net_device
  * @net_device: the device to check
  *
  * Return: batadv_hard_iface_wifi_flags flags of the device
  */
 static u32 batadv_wifi_flags_evaluate(struct net_device *net_device)
 {
     u32 wifi_flags = 0;
     struct net_device *real_netdev;
 
     if (batadv_is_wext_netdev(net_device))
         wifi_flags |= BATADV_HARDIF_WIFI_WEXT_DIRECT;
 
     if (batadv_is_cfg80211_netdev(net_device))
         wifi_flags |= BATADV_HARDIF_WIFI_CFG80211_DIRECT;
 
     real_netdev = batadv_get_real_netdevice(net_device);
     if (!real_netdev)
         return wifi_flags;
 
     if (real_netdev == net_device)
         goto out;
 
     if (batadv_is_wext_netdev(real_netdev))
         wifi_flags |= BATADV_HARDIF_WIFI_WEXT_INDIRECT;
 
     if (batadv_is_cfg80211_netdev(real_netdev))
         wifi_flags |= BATADV_HARDIF_WIFI_CFG80211_INDIRECT;
 
 out:
     dev_put(real_netdev);
     return wifi_flags;
 }
 
 /**
  * batadv_is_cfg80211_hardif() - check if the given hardif is a cfg80211 wifi
  *  interface
  * @hard_iface: the device to check
  *
  * Return: true if the net device is a cfg80211 wireless device, false
  *  otherwise.
  */
 bool batadv_is_cfg80211_hardif(struct batadv_hard_iface *hard_iface)
 {
     u32 allowed_flags = 0;
 
     allowed_flags |= BATADV_HARDIF_WIFI_CFG80211_DIRECT;
     allowed_flags |= BATADV_HARDIF_WIFI_CFG80211_INDIRECT;
 
     return !!(hard_iface->wifi_flags & allowed_flags);
 }
 
 /**
  * batadv_is_wifi_hardif() - check if the given hardif is a wifi interface
  * @hard_iface: the device to check
  *
  * Return: true if the net device is a 802.11 wireless device, false otherwise.
  */
 bool batadv_is_wifi_hardif(struct batadv_hard_iface *hard_iface)
 {
     if (!hard_iface)
         return false;
 
     return hard_iface->wifi_flags != 0;
 }
 
 /**
  * batadv_hardif_no_broadcast() - check whether (re)broadcast is necessary
  * @if_outgoing: the outgoing interface checked and considered for (re)broadcast
  * @orig_addr: the originator of this packet
  * @orig_neigh: originator address of the forwarder we just got the packet from
  *  (NULL if we originated)
  *
  * Checks whether a packet needs to be (re)broadcasted on the given interface.
  *
  * Return:
  *  BATADV_HARDIF_BCAST_NORECIPIENT: No neighbor on interface
  *  BATADV_HARDIF_BCAST_DUPFWD: Just one neighbor, but it is the forwarder
  *  BATADV_HARDIF_BCAST_DUPORIG: Just one neighbor, but it is the originator
  *  BATADV_HARDIF_BCAST_OK: Several neighbors, must broadcast
  */
 int batadv_hardif_no_broadcast(struct batadv_hard_iface *if_outgoing,
                    u8 *orig_addr, u8 *orig_neigh)
 {
     struct batadv_hardif_neigh_node *hardif_neigh;
     struct hlist_node *first;
     int ret = BATADV_HARDIF_BCAST_OK;
 
     rcu_read_lock();
 
     /* 0 neighbors -> no (re)broadcast */
     first = rcu_dereference(hlist_first_rcu(&if_outgoing->neigh_list));
     if (!first) {
         ret = BATADV_HARDIF_BCAST_NORECIPIENT;
         goto out;
     }
 
     /* >1 neighbors -> (re)broadcast */
     if (rcu_dereference(hlist_next_rcu(first)))
         goto out;
 
     hardif_neigh = hlist_entry(first, struct batadv_hardif_neigh_node,
                    list);
 
     /* 1 neighbor, is the originator -> no rebroadcast */
     if (orig_addr && batadv_compare_eth(hardif_neigh->orig, orig_addr)) {
         ret = BATADV_HARDIF_BCAST_DUPORIG;
     /* 1 neighbor, is the one we received from -> no rebroadcast */
     } else if (orig_neigh &&
            batadv_compare_eth(hardif_neigh->orig, orig_neigh)) {
         ret = BATADV_HARDIF_BCAST_DUPFWD;
     }
 
 out:
     rcu_read_unlock();
     return ret;
 }
 
 static struct batadv_hard_iface *
 batadv_hardif_get_active(const struct net_device *soft_iface)
 {
     struct batadv_hard_iface *hard_iface;
 
     rcu_read_lock();
     list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
         if (hard_iface->soft_iface != soft_iface)
             continue;
 
         if (hard_iface->if_status == BATADV_IF_ACTIVE &&
             kref_get_unless_zero(&hard_iface->refcount))
             goto out;
     }
 
     hard_iface = NULL;
 
 out:
     rcu_read_unlock();
     return hard_iface;
 }
 
 static void batadv_primary_if_update_addr(struct batadv_priv *bat_priv,
                       struct batadv_hard_iface *oldif)
 {
     struct batadv_hard_iface *primary_if;
 
     primary_if = batadv_primary_if_get_selected(bat_priv);
     if (!primary_if)
         goto out;
 
     batadv_dat_init_own_addr(bat_priv, primary_if);
     batadv_bla_update_orig_address(bat_priv, primary_if, oldif);
 out:
     batadv_hardif_put(primary_if);
 }
 
 static void batadv_primary_if_select(struct batadv_priv *bat_priv,
                      struct batadv_hard_iface *new_hard_iface)
 {
     struct batadv_hard_iface *curr_hard_iface;
 
     ASSERT_RTNL();
 
     if (new_hard_iface)
         kref_get(&new_hard_iface->refcount);
 
     curr_hard_iface = rcu_replace_pointer(bat_priv->primary_if,
                           new_hard_iface, 1);
 
     if (!new_hard_iface)
         goto out;
 
     bat_priv->algo_ops->iface.primary_set(new_hard_iface);
     batadv_primary_if_update_addr(bat_priv, curr_hard_iface);
 
 out:
     batadv_hardif_put(curr_hard_iface);
 }
 
 static bool
 batadv_hardif_is_iface_up(const struct batadv_hard_iface *hard_iface)
 {
     if (hard_iface->net_dev->flags & IFF_UP)
         return true;
 
     return false;
 }
 
 static void batadv_check_known_mac_addr(const struct net_device *net_dev)
 {
     const struct batadv_hard_iface *hard_iface;
 
     rcu_read_lock();
     list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
         if (hard_iface->if_status != BATADV_IF_ACTIVE &&
             hard_iface->if_status != BATADV_IF_TO_BE_ACTIVATED)
             continue;
 
         if (hard_iface->net_dev == net_dev)
             continue;
 
         if (!batadv_compare_eth(hard_iface->net_dev->dev_addr,
                     net_dev->dev_addr))
             continue;
 
         pr_warn("The newly added mac address (%pM) already exists on: %s\n",
             net_dev->dev_addr, hard_iface->net_dev->name);
         pr_warn("It is strongly recommended to keep mac addresses unique to avoid problems!\n");
     }
     rcu_read_unlock();
 }
 
 /**
  * batadv_hardif_recalc_extra_skbroom() - Recalculate skbuff extra head/tailroom
  * @soft_iface: netdev struct of the mesh interface
  */
 static void batadv_hardif_recalc_extra_skbroom(struct net_device *soft_iface)
 {
     const struct batadv_hard_iface *hard_iface;
     unsigned short lower_header_len = ETH_HLEN;
     unsigned short lower_headroom = 0;
     unsigned short lower_tailroom = 0;
     unsigned short needed_headroom;
 
     rcu_read_lock();
     list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
         if (hard_iface->if_status == BATADV_IF_NOT_IN_USE)
             continue;
 
         if (hard_iface->soft_iface != soft_iface)
             continue;
 
         lower_header_len = max_t(unsigned short, lower_header_len,
                      hard_iface->net_dev->hard_header_len);
 
         lower_headroom = max_t(unsigned short, lower_headroom,
                        hard_iface->net_dev->needed_headroom);
 
         lower_tailroom = max_t(unsigned short, lower_tailroom,
                        hard_iface->net_dev->needed_tailroom);
     }
     rcu_read_unlock();
 
     needed_headroom = lower_headroom + (lower_header_len - ETH_HLEN);
     needed_headroom += batadv_max_header_len();
 
     /* fragmentation headers don't strip the unicast/... header */
     needed_headroom += sizeof(struct batadv_frag_packet);
 
     soft_iface->needed_headroom = needed_headroom;
     soft_iface->needed_tailroom = lower_tailroom;
 }
 
 /**
  * batadv_hardif_min_mtu() - Calculate maximum MTU for soft interface
  * @soft_iface: netdev struct of the soft interface
  *
  * Return: MTU for the soft-interface (limited by the minimal MTU of all active
  *  slave interfaces)
  */
 int batadv_hardif_min_mtu(struct net_device *soft_iface)
 {
     struct batadv_priv *bat_priv = netdev_priv(soft_iface);
     const struct batadv_hard_iface *hard_iface;
     int min_mtu = INT_MAX;
 
     rcu_read_lock();
     list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
         if (hard_iface->if_status != BATADV_IF_ACTIVE &&
             hard_iface->if_status != BATADV_IF_TO_BE_ACTIVATED)
             continue;
 
         if (hard_iface->soft_iface != soft_iface)
             continue;
 
         min_mtu = min_t(int, hard_iface->net_dev->mtu, min_mtu);
     }
     rcu_read_unlock();
 
     if (atomic_read(&bat_priv->fragmentation) == 0)
         goto out;
 
     /* with fragmentation enabled the maximum size of internally generated
      * packets such as translation table exchanges or tvlv containers, etc
      * has to be calculated
      */
     min_mtu = min_t(int, min_mtu, BATADV_FRAG_MAX_FRAG_SIZE);
     min_mtu -= sizeof(struct batadv_frag_packet);
     min_mtu *= BATADV_FRAG_MAX_FRAGMENTS;
 
 out:
     /* report to the other components the maximum amount of bytes that
      * batman-adv can send over the wire (without considering the payload
      * overhead). For example, this value is used by TT to compute the
      * maximum local table size
      */
     atomic_set(&bat_priv->packet_size_max, min_mtu);
 
     /* the real soft-interface MTU is computed by removing the payload
      * overhead from the maximum amount of bytes that was just computed.
      *
      * However batman-adv does not support MTUs bigger than ETH_DATA_LEN
      */
     return min_t(int, min_mtu - batadv_max_header_len(), ETH_DATA_LEN);
 }
 
 /**
  * batadv_update_min_mtu() - Adjusts the MTU if a new interface with a smaller
  *  MTU appeared
  * @soft_iface: netdev struct of the soft interface
  */
 void batadv_update_min_mtu(struct net_device *soft_iface)
 {
     soft_iface->mtu = batadv_hardif_min_mtu(soft_iface);
 
     /* Check if the local translate table should be cleaned up to match a
      * new (and smaller) MTU.
      */
     batadv_tt_local_resize_to_mtu(soft_iface);
 }
 
 static void
 batadv_hardif_activate_interface(struct batadv_hard_iface *hard_iface)
 {
     struct batadv_priv *bat_priv;
     struct batadv_hard_iface *primary_if = NULL;
 
     if (hard_iface->if_status != BATADV_IF_INACTIVE)
         goto out;
 
     bat_priv = netdev_priv(hard_iface->soft_iface);
 
     bat_priv->algo_ops->iface.update_mac(hard_iface);
     hard_iface->if_status = BATADV_IF_TO_BE_ACTIVATED;
 
     /* the first active interface becomes our primary interface or
      * the next active interface after the old primary interface was removed
      */
     primary_if = batadv_primary_if_get_selected(bat_priv);
     if (!primary_if)
         batadv_primary_if_select(bat_priv, hard_iface);
 
     batadv_info(hard_iface->soft_iface, "Interface activated: %s\n",
             hard_iface->net_dev->name);
 
     batadv_update_min_mtu(hard_iface->soft_iface);
 
     if (bat_priv->algo_ops->iface.activate)
         bat_priv->algo_ops->iface.activate(hard_iface);
 
 out:
     batadv_hardif_put(primary_if);
 }
 
 static void
 batadv_hardif_deactivate_interface(struct batadv_hard_iface *hard_iface)
 {
     if (hard_iface->if_status != BATADV_IF_ACTIVE &&
         hard_iface->if_status != BATADV_IF_TO_BE_ACTIVATED)
         return;
 
     hard_iface->if_status = BATADV_IF_INACTIVE;
 
     batadv_info(hard_iface->soft_iface, "Interface deactivated: %s\n",
             hard_iface->net_dev->name);
 
     batadv_update_min_mtu(hard_iface->soft_iface);
 }
 
 /**
  * batadv_hardif_enable_interface() - Enslave hard interface to soft interface
  * @hard_iface: hard interface to add to soft interface
  * @soft_iface: netdev struct of the mesh interface
  *
  * Return: 0 on success or negative error number in case of failure
  */
 int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
                    struct net_device *soft_iface)
 {
     struct batadv_priv *bat_priv;
     __be16 ethertype = htons(ETH_P_BATMAN);
     int max_header_len = batadv_max_header_len();
     int ret;
 
     if (hard_iface->net_dev->mtu < ETH_MIN_MTU + max_header_len)
         return -EINVAL;
 
     if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
         goto out;
 
     kref_get(&hard_iface->refcount);
 
     dev_hold(soft_iface);
     hard_iface->soft_iface = soft_iface;
     bat_priv = netdev_priv(hard_iface->soft_iface);
 
     ret = netdev_master_upper_dev_link(hard_iface->net_dev,
                        soft_iface, NULL, NULL, NULL);
     if (ret)
         goto err_dev;
 
     ret = bat_priv->algo_ops->iface.enable(hard_iface);
     if (ret < 0)
         goto err_upper;
 
     hard_iface->if_status = BATADV_IF_INACTIVE;
 
     kref_get(&hard_iface->refcount);
     hard_iface->batman_adv_ptype.type = ethertype;
     hard_iface->batman_adv_ptype.func = batadv_batman_skb_recv;
     hard_iface->batman_adv_ptype.dev = hard_iface->net_dev;
     dev_add_pack(&hard_iface->batman_adv_ptype);
 
     batadv_info(hard_iface->soft_iface, "Adding interface: %s\n",
             hard_iface->net_dev->name);
 
     if (atomic_read(&bat_priv->fragmentation) &&
         hard_iface->net_dev->mtu < ETH_DATA_LEN + max_header_len)
         batadv_info(hard_iface->soft_iface,
                 "The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to %i would solve the problem.\n",
                 hard_iface->net_dev->name, hard_iface->net_dev->mtu,
                 ETH_DATA_LEN + max_header_len);
 
     if (!atomic_read(&bat_priv->fragmentation) &&
         hard_iface->net_dev->mtu < ETH_DATA_LEN + max_header_len)
         batadv_info(hard_iface->soft_iface,
                 "The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. If you experience problems getting traffic through try increasing the MTU to %i.\n",
                 hard_iface->net_dev->name, hard_iface->net_dev->mtu,
                 ETH_DATA_LEN + max_header_len);
 
     if (batadv_hardif_is_iface_up(hard_iface))
         batadv_hardif_activate_interface(hard_iface);
     else
         batadv_err(hard_iface->soft_iface,
                "Not using interface %s (retrying later): interface not active\n",
                hard_iface->net_dev->name);
 
     batadv_hardif_recalc_extra_skbroom(soft_iface);
 
     if (bat_priv->algo_ops->iface.enabled)
         bat_priv->algo_ops->iface.enabled(hard_iface);
 
 out:
     return 0;
 
 err_upper:
     netdev_upper_dev_unlink(hard_iface->net_dev, soft_iface);
 err_dev:
     hard_iface->soft_iface = NULL;
     dev_put(soft_iface);
     batadv_hardif_put(hard_iface);
     return ret;
 }
 
 /**
  * batadv_hardif_cnt() - get number of interfaces enslaved to soft interface
  * @soft_iface: soft interface to check
  *
  * This function is only using RCU for locking - the result can therefore be
  * off when another function is modifying the list at the same time. The
  * caller can use the rtnl_lock to make sure that the count is accurate.
  *
  * Return: number of connected/enslaved hard interfaces
  */
 static size_t batadv_hardif_cnt(const struct net_device *soft_iface)
 {
     struct batadv_hard_iface *hard_iface;
     size_t count = 0;
 
     rcu_read_lock();
     list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
         if (hard_iface->soft_iface != soft_iface)
             continue;
 
         count++;
     }
     rcu_read_unlock();
 
     return count;
 }
 
 /**
  * batadv_hardif_disable_interface() - Remove hard interface from soft interface
  * @hard_iface: hard interface to be removed
  */
 void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface)
 {
     struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
     struct batadv_hard_iface *primary_if = NULL;
 
     batadv_hardif_deactivate_interface(hard_iface);
 
     if (hard_iface->if_status != BATADV_IF_INACTIVE)
         goto out;
 
     batadv_info(hard_iface->soft_iface, "Removing interface: %s\n",
             hard_iface->net_dev->name);
     dev_remove_pack(&hard_iface->batman_adv_ptype);
     batadv_hardif_put(hard_iface);
 
     primary_if = batadv_primary_if_get_selected(bat_priv);
     if (hard_iface == primary_if) {
         struct batadv_hard_iface *new_if;
 
         new_if = batadv_hardif_get_active(hard_iface->soft_iface);
         batadv_primary_if_select(bat_priv, new_if);
 
         batadv_hardif_put(new_if);
     }
 
     bat_priv->algo_ops->iface.disable(hard_iface);
     hard_iface->if_status = BATADV_IF_NOT_IN_USE;
 
     /* delete all references to this hard_iface */
     batadv_purge_orig_ref(bat_priv);
     batadv_purge_outstanding_packets(bat_priv, hard_iface);
     dev_put(hard_iface->soft_iface);
 
     netdev_upper_dev_unlink(hard_iface->net_dev, hard_iface->soft_iface);
     batadv_hardif_recalc_extra_skbroom(hard_iface->soft_iface);
 
     /* nobody uses this interface anymore */
     if (batadv_hardif_cnt(hard_iface->soft_iface) <= 1)
         batadv_gw_check_client_stop(bat_priv);
 
     hard_iface->soft_iface = NULL;
     batadv_hardif_put(hard_iface);
 
 out:
     batadv_hardif_put(primary_if);
 }
 
 static struct batadv_hard_iface *
 batadv_hardif_add_interface(struct net_device *net_dev)
 {
     struct batadv_hard_iface *hard_iface;
 
     ASSERT_RTNL();
 
     if (!batadv_is_valid_iface(net_dev))
         goto out;
 
     dev_hold(net_dev);
 
     hard_iface = kzalloc(sizeof(*hard_iface), GFP_ATOMIC);
     if (!hard_iface)
         goto release_dev;
 
     hard_iface->net_dev = net_dev;
     hard_iface->soft_iface = NULL;
     hard_iface->if_status = BATADV_IF_NOT_IN_USE;
 
     INIT_LIST_HEAD(&hard_iface->list);
     INIT_HLIST_HEAD(&hard_iface->neigh_list);
 
     mutex_init(&hard_iface->bat_iv.ogm_buff_mutex);
     spin_lock_init(&hard_iface->neigh_list_lock);
     kref_init(&hard_iface->refcount);
 
     hard_iface->num_bcasts = BATADV_NUM_BCASTS_DEFAULT;
     hard_iface->wifi_flags = batadv_wifi_flags_evaluate(net_dev);
     if (batadv_is_wifi_hardif(hard_iface))
         hard_iface->num_bcasts = BATADV_NUM_BCASTS_WIRELESS;
 
     atomic_set(&hard_iface->hop_penalty, 0);
 
     batadv_v_hardif_init(hard_iface);
 
     batadv_check_known_mac_addr(hard_iface->net_dev);
     kref_get(&hard_iface->refcount);
     list_add_tail_rcu(&hard_iface->list, &batadv_hardif_list);
     batadv_hardif_generation++;
 
     return hard_iface;
 
 release_dev:
     dev_put(net_dev);
 out:
     return NULL;
 }
 
 static void batadv_hardif_remove_interface(struct batadv_hard_iface *hard_iface)
 {
     ASSERT_RTNL();
 
     /* first deactivate interface */
     if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
         batadv_hardif_disable_interface(hard_iface);
 
     if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
         return;
 
     hard_iface->if_status = BATADV_IF_TO_BE_REMOVED;
     batadv_hardif_put(hard_iface);
 }
 
 /**
  * batadv_hard_if_event_softif() - Handle events for soft interfaces
  * @event: NETDEV_* event to handle
  * @net_dev: net_device which generated an event
  *
  * Return: NOTIFY_* result
  */
 static int batadv_hard_if_event_softif(unsigned long event,
                        struct net_device *net_dev)
 {
     struct batadv_priv *bat_priv;
 
     switch (event) {
     case NETDEV_REGISTER:
         bat_priv = netdev_priv(net_dev);
         batadv_softif_create_vlan(bat_priv, BATADV_NO_FLAGS);
         break;
     }
 
     return NOTIFY_DONE;
 }
 
 static int batadv_hard_if_event(struct notifier_block *this,
                 unsigned long event, void *ptr)
 {
     struct net_device *net_dev = netdev_notifier_info_to_dev(ptr);
     struct batadv_hard_iface *hard_iface;
     struct batadv_hard_iface *primary_if = NULL;
     struct batadv_priv *bat_priv;
 
     if (batadv_softif_is_valid(net_dev))
         return batadv_hard_if_event_softif(event, net_dev);
 
     hard_iface = batadv_hardif_get_by_netdev(net_dev);
     if (!hard_iface && (event == NETDEV_REGISTER ||
                 event == NETDEV_POST_TYPE_CHANGE))
         hard_iface = batadv_hardif_add_interface(net_dev);
 
     if (!hard_iface)
         goto out;
 
     switch (event) {
     case NETDEV_UP:
         batadv_hardif_activate_interface(hard_iface);
         break;
     case NETDEV_GOING_DOWN:
     case NETDEV_DOWN:
         batadv_hardif_deactivate_interface(hard_iface);
         break;
     case NETDEV_UNREGISTER:
     case NETDEV_PRE_TYPE_CHANGE:
         list_del_rcu(&hard_iface->list);
         batadv_hardif_generation++;
 
         batadv_hardif_remove_interface(hard_iface);
         break;
     case NETDEV_CHANGEMTU:
         if (hard_iface->soft_iface)
             batadv_update_min_mtu(hard_iface->soft_iface);
         break;
     case NETDEV_CHANGEADDR:
         if (hard_iface->if_status == BATADV_IF_NOT_IN_USE)
             goto hardif_put;
 
         batadv_check_known_mac_addr(hard_iface->net_dev);
 
         bat_priv = netdev_priv(hard_iface->soft_iface);
         bat_priv->algo_ops->iface.update_mac(hard_iface);
 
         primary_if = batadv_primary_if_get_selected(bat_priv);
         if (!primary_if)
             goto hardif_put;
 
         if (hard_iface == primary_if)
             batadv_primary_if_update_addr(bat_priv, NULL);
         break;
     case NETDEV_CHANGEUPPER:
         hard_iface->wifi_flags = batadv_wifi_flags_evaluate(net_dev);
         if (batadv_is_wifi_hardif(hard_iface))
             hard_iface->num_bcasts = BATADV_NUM_BCASTS_WIRELESS;
         break;
     default:
         break;
     }
 
 hardif_put:
     batadv_hardif_put(hard_iface);
 out:
     batadv_hardif_put(primary_if);
     return NOTIFY_DONE;
 }
 
 struct notifier_block batadv_hard_if_notifier = {
     .notifier_call = batadv_hard_if_event,
 };

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