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	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-only
 /******************************************************************************
 *******************************************************************************
 **
 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
 **  Copyright (C) 2004-2009 Red Hat, Inc.  All rights reserved.
 **
 **
 *******************************************************************************
 ******************************************************************************/
 
 /*
  * lowcomms.c
  *
  * This is the "low-level" comms layer.
  *
  * It is responsible for sending/receiving messages
  * from other nodes in the cluster.
  *
  * Cluster nodes are referred to by their nodeids. nodeids are
  * simply 32 bit numbers to the locking module - if they need to
  * be expanded for the cluster infrastructure then that is its
  * responsibility. It is this layer's
  * responsibility to resolve these into IP address or
  * whatever it needs for inter-node communication.
  *
  * The comms level is two kernel threads that deal mainly with
  * the receiving of messages from other nodes and passing them
  * up to the mid-level comms layer (which understands the
  * message format) for execution by the locking core, and
  * a send thread which does all the setting up of connections
  * to remote nodes and the sending of data. Threads are not allowed
  * to send their own data because it may cause them to wait in times
  * of high load. Also, this way, the sending thread can collect together
  * messages bound for one node and send them in one block.
  *
  * lowcomms will choose to use either TCP or SCTP as its transport layer
  * depending on the configuration variable 'protocol'. This should be set
  * to 0 (default) for TCP or 1 for SCTP. It should be configured using a
  * cluster-wide mechanism as it must be the same on all nodes of the cluster
  * for the DLM to function.
  *
  */
 
 #include <asm/ioctls.h>
 #include <net/sock.h>
 #include <net/tcp.h>
 #include <linux/pagemap.h>
 #include <linux/file.h>
 #include <linux/mutex.h>
 #include <linux/sctp.h>
 #include <linux/slab.h>
 #include <net/sctp/sctp.h>
 #include <net/ipv6.h>
 
 #include <trace/events/dlm.h>
 
 #include "dlm_internal.h"
 #include "lowcomms.h"
 #include "midcomms.h"
 #include "memory.h"
 #include "config.h"
 
 #define NEEDED_RMEM (4*1024*1024)
 
 /* Number of messages to send before rescheduling */
 #define MAX_SEND_MSG_COUNT 25
 #define DLM_SHUTDOWN_WAIT_TIMEOUT msecs_to_jiffies(10000)
 
 struct connection {
     struct socket *sock;    /* NULL if not connected */
     uint32_t nodeid;    /* So we know who we are in the list */
     struct mutex sock_mutex;
     unsigned long flags;
 #define CF_READ_PENDING 1
 #define CF_WRITE_PENDING 2
 #define CF_INIT_PENDING 4
 #define CF_IS_OTHERCON 5
 #define CF_CLOSE 6
 #define CF_APP_LIMITED 7
 #define CF_CLOSING 8
 #define CF_SHUTDOWN 9
 #define CF_CONNECTED 10
 #define CF_RECONNECT 11
 #define CF_DELAY_CONNECT 12
 #define CF_EOF 13
     struct list_head writequeue;  /* List of outgoing writequeue_entries */
     spinlock_t writequeue_lock;
     atomic_t writequeue_cnt;
     int retries;
 #define MAX_CONNECT_RETRIES 3
     struct hlist_node list;
     struct connection *othercon;
     struct connection *sendcon;
     struct work_struct rwork; /* Receive workqueue */
     struct work_struct swork; /* Send workqueue */
     wait_queue_head_t shutdown_wait; /* wait for graceful shutdown */
     unsigned char *rx_buf;
     int rx_buflen;
     int rx_leftover;
     struct rcu_head rcu;
 };
 #define sock2con(x) ((struct connection *)(x)->sk_user_data)
 
 struct listen_connection {
     struct socket *sock;
     struct work_struct rwork;
 };
 
 #define DLM_WQ_REMAIN_BYTES(e) (PAGE_SIZE - e->end)
 #define DLM_WQ_LENGTH_BYTES(e) (e->end - e->offset)
 
 /* An entry waiting to be sent */
 struct writequeue_entry {
     struct list_head list;
     struct page *page;
     int offset;
     int len;
     int end;
     int users;
     bool dirty;
     struct connection *con;
     struct list_head msgs;
     struct kref ref;
 };
 
 struct dlm_msg {
     struct writequeue_entry *entry;
     struct dlm_msg *orig_msg;
     bool retransmit;
     void *ppc;
     int len;
     int idx; /* new()/commit() idx exchange */
 
     struct list_head list;
     struct kref ref;
 };
 
 struct dlm_node_addr {
     struct list_head list;
     int nodeid;
     int mark;
     int addr_count;
     int curr_addr_index;
     struct sockaddr_storage *addr[DLM_MAX_ADDR_COUNT];
 };
 
 struct dlm_proto_ops {
     bool try_new_addr;
     const char *name;
     int proto;
 
     int (*connect)(struct connection *con, struct socket *sock,
                struct sockaddr *addr, int addr_len);
     void (*sockopts)(struct socket *sock);
     int (*bind)(struct socket *sock);
     int (*listen_validate)(void);
     void (*listen_sockopts)(struct socket *sock);
     int (*listen_bind)(struct socket *sock);
     /* What to do to shutdown */
     void (*shutdown_action)(struct connection *con);
     /* What to do to eof check */
     bool (*eof_condition)(struct connection *con);
 };
 
 static struct listen_sock_callbacks {
     void (*sk_error_report)(struct sock *);
     void (*sk_data_ready)(struct sock *);
     void (*sk_state_change)(struct sock *);
     void (*sk_write_space)(struct sock *);
 } listen_sock;
 
 static LIST_HEAD(dlm_node_addrs);
 static DEFINE_SPINLOCK(dlm_node_addrs_spin);
 
 static struct listen_connection listen_con;
 static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
 static int dlm_local_count;
 int dlm_allow_conn;
 
 /* Work queues */
 static struct workqueue_struct *recv_workqueue;
 static struct workqueue_struct *send_workqueue;
 
 static struct hlist_head connection_hash[CONN_HASH_SIZE];
 static DEFINE_SPINLOCK(connections_lock);
 DEFINE_STATIC_SRCU(connections_srcu);
 
 static const struct dlm_proto_ops *dlm_proto_ops;
 
 static void process_recv_sockets(struct work_struct *work);
 static void process_send_sockets(struct work_struct *work);
 
 static void writequeue_entry_ctor(void *data)
 {
     struct writequeue_entry *entry = data;
 
     INIT_LIST_HEAD(&entry->msgs);
 }
 
 struct kmem_cache *dlm_lowcomms_writequeue_cache_create(void)
 {
     return kmem_cache_create("dlm_writequeue", sizeof(struct writequeue_entry),
                  0, 0, writequeue_entry_ctor);
 }
 
 struct kmem_cache *dlm_lowcomms_msg_cache_create(void)
 {
     return kmem_cache_create("dlm_msg", sizeof(struct dlm_msg), 0, 0, NULL);
 }
 
 /* need to held writequeue_lock */
 static struct writequeue_entry *con_next_wq(struct connection *con)
 {
     struct writequeue_entry *e;
 
     if (list_empty(&con->writequeue))
         return NULL;
 
     e = list_first_entry(&con->writequeue, struct writequeue_entry,
                  list);
     /* if len is zero nothing is to send, if there are users filling
      * buffers we wait until the users are done so we can send more.
      */
     if (e->users || e->len == 0)
         return NULL;
 
     return e;
 }
 
 static struct connection *__find_con(int nodeid, int r)
 {
     struct connection *con;
 
     hlist_for_each_entry_rcu(con, &connection_hash[r], list) {
         if (con->nodeid == nodeid)
             return con;
     }
 
     return NULL;
 }
 
 static bool tcp_eof_condition(struct connection *con)
 {
     return atomic_read(&con->writequeue_cnt);
 }
 
 static int dlm_con_init(struct connection *con, int nodeid)
 {
     con->rx_buflen = dlm_config.ci_buffer_size;
     con->rx_buf = kmalloc(con->rx_buflen, GFP_NOFS);
     if (!con->rx_buf)
         return -ENOMEM;
 
     con->nodeid = nodeid;
     mutex_init(&con->sock_mutex);
     INIT_LIST_HEAD(&con->writequeue);
     spin_lock_init(&con->writequeue_lock);
     atomic_set(&con->writequeue_cnt, 0);
     INIT_WORK(&con->swork, process_send_sockets);
     INIT_WORK(&con->rwork, process_recv_sockets);
     init_waitqueue_head(&con->shutdown_wait);
 
     return 0;
 }
 
 /*
  * If 'allocation' is zero then we don't attempt to create a new
  * connection structure for this node.
  */
 static struct connection *nodeid2con(int nodeid, gfp_t alloc)
 {
     struct connection *con, *tmp;
     int r, ret;
 
     r = nodeid_hash(nodeid);
     con = __find_con(nodeid, r);
     if (con || !alloc)
         return con;
 
     con = kzalloc(sizeof(*con), alloc);
     if (!con)
         return NULL;
 
     ret = dlm_con_init(con, nodeid);
     if (ret) {
         kfree(con);
         return NULL;
     }
 
     spin_lock(&connections_lock);
     /* Because multiple workqueues/threads calls this function it can
      * race on multiple cpu's. Instead of locking hot path __find_con()
      * we just check in rare cases of recently added nodes again
      * under protection of connections_lock. If this is the case we
      * abort our connection creation and return the existing connection.
      */
     tmp = __find_con(nodeid, r);
     if (tmp) {
         spin_unlock(&connections_lock);
         kfree(con->rx_buf);
         kfree(con);
         return tmp;
     }
 
     hlist_add_head_rcu(&con->list, &connection_hash[r]);
     spin_unlock(&connections_lock);
 
     return con;
 }
 
 /* Loop round all connections */
 static void foreach_conn(void (*conn_func)(struct connection *c))
 {
     int i;
     struct connection *con;
 
     for (i = 0; i < CONN_HASH_SIZE; i++) {
         hlist_for_each_entry_rcu(con, &connection_hash[i], list)
             conn_func(con);
     }
 }
 
 static struct dlm_node_addr *find_node_addr(int nodeid)
 {
     struct dlm_node_addr *na;
 
     list_for_each_entry(na, &dlm_node_addrs, list) {
         if (na->nodeid == nodeid)
             return na;
     }
     return NULL;
 }
 
 static int addr_compare(const struct sockaddr_storage *x,
             const struct sockaddr_storage *y)
 {
     switch (x->ss_family) {
     case AF_INET: {
         struct sockaddr_in *sinx = (struct sockaddr_in *)x;
         struct sockaddr_in *siny = (struct sockaddr_in *)y;
         if (sinx->sin_addr.s_addr != siny->sin_addr.s_addr)
             return 0;
         if (sinx->sin_port != siny->sin_port)
             return 0;
         break;
     }
     case AF_INET6: {
         struct sockaddr_in6 *sinx = (struct sockaddr_in6 *)x;
         struct sockaddr_in6 *siny = (struct sockaddr_in6 *)y;
         if (!ipv6_addr_equal(&sinx->sin6_addr, &siny->sin6_addr))
             return 0;
         if (sinx->sin6_port != siny->sin6_port)
             return 0;
         break;
     }
     default:
         return 0;
     }
     return 1;
 }
 
 static int nodeid_to_addr(int nodeid, struct sockaddr_storage *sas_out,
               struct sockaddr *sa_out, bool try_new_addr,
               unsigned int *mark)
 {
     struct sockaddr_storage sas;
     struct dlm_node_addr *na;
 
     if (!dlm_local_count)
         return -1;
 
     spin_lock(&dlm_node_addrs_spin);
     na = find_node_addr(nodeid);
     if (na && na->addr_count) {
         memcpy(&sas, na->addr[na->curr_addr_index],
                sizeof(struct sockaddr_storage));
 
         if (try_new_addr) {
             na->curr_addr_index++;
             if (na->curr_addr_index == na->addr_count)
                 na->curr_addr_index = 0;
         }
     }
     spin_unlock(&dlm_node_addrs_spin);
 
     if (!na)
         return -EEXIST;
 
     if (!na->addr_count)
         return -ENOENT;
 
     *mark = na->mark;
 
     if (sas_out)
         memcpy(sas_out, &sas, sizeof(struct sockaddr_storage));
 
     if (!sa_out)
         return 0;
 
     if (dlm_local_addr[0]->ss_family == AF_INET) {
         struct sockaddr_in *in4  = (struct sockaddr_in *) &sas;
         struct sockaddr_in *ret4 = (struct sockaddr_in *) sa_out;
         ret4->sin_addr.s_addr = in4->sin_addr.s_addr;
     } else {
         struct sockaddr_in6 *in6  = (struct sockaddr_in6 *) &sas;
         struct sockaddr_in6 *ret6 = (struct sockaddr_in6 *) sa_out;
         ret6->sin6_addr = in6->sin6_addr;
     }
 
     return 0;
 }
 
 static int addr_to_nodeid(struct sockaddr_storage *addr, int *nodeid,
               unsigned int *mark)
 {
     struct dlm_node_addr *na;
     int rv = -EEXIST;
     int addr_i;
 
     spin_lock(&dlm_node_addrs_spin);
     list_for_each_entry(na, &dlm_node_addrs, list) {
         if (!na->addr_count)
             continue;
 
         for (addr_i = 0; addr_i < na->addr_count; addr_i++) {
             if (addr_compare(na->addr[addr_i], addr)) {
                 *nodeid = na->nodeid;
                 *mark = na->mark;
                 rv = 0;
                 goto unlock;
             }
         }
     }
 unlock:
     spin_unlock(&dlm_node_addrs_spin);
     return rv;
 }
 
 /* caller need to held dlm_node_addrs_spin lock */
 static bool dlm_lowcomms_na_has_addr(const struct dlm_node_addr *na,
                      const struct sockaddr_storage *addr)
 {
     int i;
 
     for (i = 0; i < na->addr_count; i++) {
         if (addr_compare(na->addr[i], addr))
             return true;
     }
 
     return false;
 }
 
 int dlm_lowcomms_addr(int nodeid, struct sockaddr_storage *addr, int len)
 {
     struct sockaddr_storage *new_addr;
     struct dlm_node_addr *new_node, *na;
     bool ret;
 
     new_node = kzalloc(sizeof(struct dlm_node_addr), GFP_NOFS);
     if (!new_node)
         return -ENOMEM;
 
     new_addr = kzalloc(sizeof(struct sockaddr_storage), GFP_NOFS);
     if (!new_addr) {
         kfree(new_node);
         return -ENOMEM;
     }
 
     memcpy(new_addr, addr, len);
 
     spin_lock(&dlm_node_addrs_spin);
     na = find_node_addr(nodeid);
     if (!na) {
         new_node->nodeid = nodeid;
         new_node->addr[0] = new_addr;
         new_node->addr_count = 1;
         new_node->mark = dlm_config.ci_mark;
         list_add(&new_node->list, &dlm_node_addrs);
         spin_unlock(&dlm_node_addrs_spin);
         return 0;
     }
 
     ret = dlm_lowcomms_na_has_addr(na, addr);
     if (ret) {
         spin_unlock(&dlm_node_addrs_spin);
         kfree(new_addr);
         kfree(new_node);
         return -EEXIST;
     }
 
     if (na->addr_count >= DLM_MAX_ADDR_COUNT) {
         spin_unlock(&dlm_node_addrs_spin);
         kfree(new_addr);
         kfree(new_node);
         return -ENOSPC;
     }
 
     na->addr[na->addr_count++] = new_addr;
     spin_unlock(&dlm_node_addrs_spin);
     kfree(new_node);
     return 0;
 }
 
 /* Data available on socket or listen socket received a connect */
 static void lowcomms_data_ready(struct sock *sk)
 {
     struct connection *con;
 
     con = sock2con(sk);
     if (con && !test_and_set_bit(CF_READ_PENDING, &con->flags))
         queue_work(recv_workqueue, &con->rwork);
 }
 
 static void lowcomms_listen_data_ready(struct sock *sk)
 {
     if (!dlm_allow_conn)
         return;
 
     queue_work(recv_workqueue, &listen_con.rwork);
 }
 
 static void lowcomms_write_space(struct sock *sk)
 {
     struct connection *con;
 
     con = sock2con(sk);
     if (!con)
         return;
 
     if (!test_and_set_bit(CF_CONNECTED, &con->flags)) {
         log_print("connected to node %d", con->nodeid);
         queue_work(send_workqueue, &con->swork);
         return;
     }
 
     clear_bit(SOCK_NOSPACE, &con->sock->flags);
 
     if (test_and_clear_bit(CF_APP_LIMITED, &con->flags)) {
         con->sock->sk->sk_write_pending--;
         clear_bit(SOCKWQ_ASYNC_NOSPACE, &con->sock->flags);
     }
 
     queue_work(send_workqueue, &con->swork);
 }
 
 static inline void lowcomms_connect_sock(struct connection *con)
 {
     if (test_bit(CF_CLOSE, &con->flags))
         return;
     queue_work(send_workqueue, &con->swork);
     cond_resched();
 }
 
 static void lowcomms_state_change(struct sock *sk)
 {
     /* SCTP layer is not calling sk_data_ready when the connection
      * is done, so we catch the signal through here. Also, it
      * doesn't switch socket state when entering shutdown, so we
      * skip the write in that case.
      */
     if (sk->sk_shutdown) {
         if (sk->sk_shutdown == RCV_SHUTDOWN)
             lowcomms_data_ready(sk);
     } else if (sk->sk_state == TCP_ESTABLISHED) {
         lowcomms_write_space(sk);
     }
 }
 
 int dlm_lowcomms_connect_node(int nodeid)
 {
     struct connection *con;
     int idx;
 
     if (nodeid == dlm_our_nodeid())
         return 0;
 
     idx = srcu_read_lock(&connections_srcu);
     con = nodeid2con(nodeid, GFP_NOFS);
     if (!con) {
         srcu_read_unlock(&connections_srcu, idx);
         return -ENOMEM;
     }
 
     lowcomms_connect_sock(con);
     srcu_read_unlock(&connections_srcu, idx);
 
     return 0;
 }
 
 int dlm_lowcomms_nodes_set_mark(int nodeid, unsigned int mark)
 {
     struct dlm_node_addr *na;
 
     spin_lock(&dlm_node_addrs_spin);
     na = find_node_addr(nodeid);
     if (!na) {
         spin_unlock(&dlm_node_addrs_spin);
         return -ENOENT;
     }
 
     na->mark = mark;
     spin_unlock(&dlm_node_addrs_spin);
 
     return 0;
 }
 
 static void lowcomms_error_report(struct sock *sk)
 {
     struct connection *con;
     void (*orig_report)(struct sock *) = NULL;
     struct inet_sock *inet;
 
     con = sock2con(sk);
     if (con == NULL)
         goto out;
 
     orig_report = listen_sock.sk_error_report;
 
     inet = inet_sk(sk);
     switch (sk->sk_family) {
     case AF_INET:
         printk_ratelimited(KERN_ERR "dlm: node %d: socket error "
                    "sending to node %d at %pI4, dport %d, "
                    "sk_err=%d/%d\n", dlm_our_nodeid(),
                    con->nodeid, &inet->inet_daddr,
                    ntohs(inet->inet_dport), sk->sk_err,
                    sk->sk_err_soft);
         break;
 #if IS_ENABLED(CONFIG_IPV6)
     case AF_INET6:
         printk_ratelimited(KERN_ERR "dlm: node %d: socket error "
                    "sending to node %d at %pI6c, "
                    "dport %d, sk_err=%d/%d\n", dlm_our_nodeid(),
                    con->nodeid, &sk->sk_v6_daddr,
                    ntohs(inet->inet_dport), sk->sk_err,
                    sk->sk_err_soft);
         break;
 #endif
     default:
         printk_ratelimited(KERN_ERR "dlm: node %d: socket error "
                    "invalid socket family %d set, "
                    "sk_err=%d/%d\n", dlm_our_nodeid(),
                    sk->sk_family, sk->sk_err, sk->sk_err_soft);
         goto out;
     }
 
     /* below sendcon only handling */
     if (test_bit(CF_IS_OTHERCON, &con->flags))
         con = con->sendcon;
 
     switch (sk->sk_err) {
     case ECONNREFUSED:
         set_bit(CF_DELAY_CONNECT, &con->flags);
         break;
     default:
         break;
     }
 
     if (!test_and_set_bit(CF_RECONNECT, &con->flags))
         queue_work(send_workqueue, &con->swork);
 
 out:
     if (orig_report)
         orig_report(sk);
 }
 
 /* Note: sk_callback_lock must be locked before calling this function. */
 static void save_listen_callbacks(struct socket *sock)
 {
     struct sock *sk = sock->sk;
 
     listen_sock.sk_data_ready = sk->sk_data_ready;
     listen_sock.sk_state_change = sk->sk_state_change;
     listen_sock.sk_write_space = sk->sk_write_space;
     listen_sock.sk_error_report = sk->sk_error_report;
 }
 
 static void restore_callbacks(struct socket *sock)
 {
     struct sock *sk = sock->sk;
 
     lock_sock(sk);
     sk->sk_user_data = NULL;
     sk->sk_data_ready = listen_sock.sk_data_ready;
     sk->sk_state_change = listen_sock.sk_state_change;
     sk->sk_write_space = listen_sock.sk_write_space;
     sk->sk_error_report = listen_sock.sk_error_report;
     release_sock(sk);
 }
 
 static void add_listen_sock(struct socket *sock, struct listen_connection *con)
 {
     struct sock *sk = sock->sk;
 
     lock_sock(sk);
     save_listen_callbacks(sock);
     con->sock = sock;
 
     sk->sk_user_data = con;
     sk->sk_allocation = GFP_NOFS;
     /* Install a data_ready callback */
     sk->sk_data_ready = lowcomms_listen_data_ready;
     release_sock(sk);
 }
 
 /* Make a socket active */
 static void add_sock(struct socket *sock, struct connection *con)
 {
     struct sock *sk = sock->sk;
 
     lock_sock(sk);
     con->sock = sock;
 
     sk->sk_user_data = con;
     /* Install a data_ready callback */
     sk->sk_data_ready = lowcomms_data_ready;
     sk->sk_write_space = lowcomms_write_space;
     sk->sk_state_change = lowcomms_state_change;
     sk->sk_allocation = GFP_NOFS;
     sk->sk_error_report = lowcomms_error_report;
     release_sock(sk);
 }
 
 /* Add the port number to an IPv6 or 4 sockaddr and return the address
    length */
 static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
               int *addr_len)
 {
     saddr->ss_family =  dlm_local_addr[0]->ss_family;
     if (saddr->ss_family == AF_INET) {
         struct sockaddr_in *in4_addr = (struct sockaddr_in *)saddr;
         in4_addr->sin_port = cpu_to_be16(port);
         *addr_len = sizeof(struct sockaddr_in);
         memset(&in4_addr->sin_zero, 0, sizeof(in4_addr->sin_zero));
     } else {
         struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)saddr;
         in6_addr->sin6_port = cpu_to_be16(port);
         *addr_len = sizeof(struct sockaddr_in6);
     }
     memset((char *)saddr + *addr_len, 0, sizeof(struct sockaddr_storage) - *addr_len);
 }
 
 static void dlm_page_release(struct kref *kref)
 {
     struct writequeue_entry *e = container_of(kref, struct writequeue_entry,
                           ref);
 
     __free_page(e->page);
     dlm_free_writequeue(e);
 }
 
 static void dlm_msg_release(struct kref *kref)
 {
     struct dlm_msg *msg = container_of(kref, struct dlm_msg, ref);
 
     kref_put(&msg->entry->ref, dlm_page_release);
     dlm_free_msg(msg);
 }
 
 static void free_entry(struct writequeue_entry *e)
 {
     struct dlm_msg *msg, *tmp;
 
     list_for_each_entry_safe(msg, tmp, &e->msgs, list) {
         if (msg->orig_msg) {
             msg->orig_msg->retransmit = false;
             kref_put(&msg->orig_msg->ref, dlm_msg_release);
         }
 
         list_del(&msg->list);
         kref_put(&msg->ref, dlm_msg_release);
     }
 
     list_del(&e->list);
     atomic_dec(&e->con->writequeue_cnt);
     kref_put(&e->ref, dlm_page_release);
 }
 
 static void dlm_close_sock(struct socket **sock)
 {
     if (*sock) {
         restore_callbacks(*sock);
         sock_release(*sock);
         *sock = NULL;
     }
 }
 
 /* Close a remote connection and tidy up */
 static void close_connection(struct connection *con, bool and_other,
                  bool tx, bool rx)
 {
     bool closing = test_and_set_bit(CF_CLOSING, &con->flags);
     struct writequeue_entry *e;
 
     if (tx && !closing && cancel_work_sync(&con->swork)) {
         log_print("canceled swork for node %d", con->nodeid);
         clear_bit(CF_WRITE_PENDING, &con->flags);
     }
     if (rx && !closing && cancel_work_sync(&con->rwork)) {
         log_print("canceled rwork for node %d", con->nodeid);
         clear_bit(CF_READ_PENDING, &con->flags);
     }
 
     mutex_lock(&con->sock_mutex);
     dlm_close_sock(&con->sock);
 
     if (con->othercon && and_other) {
         /* Will only re-enter once. */
         close_connection(con->othercon, false, tx, rx);
     }
 
     /* if we send a writequeue entry only a half way, we drop the
      * whole entry because reconnection and that we not start of the
      * middle of a msg which will confuse the other end.
      *
      * we can always drop messages because retransmits, but what we
      * cannot allow is to transmit half messages which may be processed
      * at the other side.
      *
      * our policy is to start on a clean state when disconnects, we don't
      * know what's send/received on transport layer in this case.
      */
     spin_lock(&con->writequeue_lock);
     if (!list_empty(&con->writequeue)) {
         e = list_first_entry(&con->writequeue, struct writequeue_entry,
                      list);
         if (e->dirty)
             free_entry(e);
     }
     spin_unlock(&con->writequeue_lock);
 
     con->rx_leftover = 0;
     con->retries = 0;
     clear_bit(CF_APP_LIMITED, &con->flags);
     clear_bit(CF_CONNECTED, &con->flags);
     clear_bit(CF_DELAY_CONNECT, &con->flags);
     clear_bit(CF_RECONNECT, &con->flags);
     clear_bit(CF_EOF, &con->flags);
     mutex_unlock(&con->sock_mutex);
     clear_bit(CF_CLOSING, &con->flags);
 }
 
 static void shutdown_connection(struct connection *con)
 {
     int ret;
 
     flush_work(&con->swork);
 
     mutex_lock(&con->sock_mutex);
     /* nothing to shutdown */
     if (!con->sock) {
         mutex_unlock(&con->sock_mutex);
         return;
     }
 
     set_bit(CF_SHUTDOWN, &con->flags);
     ret = kernel_sock_shutdown(con->sock, SHUT_WR);
     mutex_unlock(&con->sock_mutex);
     if (ret) {
         log_print("Connection %p failed to shutdown: %d will force close",
               con, ret);
         goto force_close;
     } else {
         ret = wait_event_timeout(con->shutdown_wait,
                      !test_bit(CF_SHUTDOWN, &con->flags),
                      DLM_SHUTDOWN_WAIT_TIMEOUT);
         if (ret == 0) {
             log_print("Connection %p shutdown timed out, will force close",
                   con);
             goto force_close;
         }
     }
 
     return;
 
 force_close:
     clear_bit(CF_SHUTDOWN, &con->flags);
     close_connection(con, false, true, true);
 }
 
 static void dlm_tcp_shutdown(struct connection *con)
 {
     if (con->othercon)
         shutdown_connection(con->othercon);
     shutdown_connection(con);
 }
 
 static int con_realloc_receive_buf(struct connection *con, int newlen)
 {
     unsigned char *newbuf;
 
     newbuf = kmalloc(newlen, GFP_NOFS);
     if (!newbuf)
         return -ENOMEM;
 
     /* copy any leftover from last receive */
     if (con->rx_leftover)
         memmove(newbuf, con->rx_buf, con->rx_leftover);
 
     /* swap to new buffer space */
     kfree(con->rx_buf);
     con->rx_buflen = newlen;
     con->rx_buf = newbuf;
 
     return 0;
 }
 
 /* Data received from remote end */
 static int receive_from_sock(struct connection *con)
 {
     struct msghdr msg;
     struct kvec iov;
     int ret, buflen;
 
     mutex_lock(&con->sock_mutex);
 
     if (con->sock == NULL) {
         ret = -EAGAIN;
         goto out_close;
     }
 
     /* realloc if we get new buffer size to read out */
     buflen = dlm_config.ci_buffer_size;
     if (con->rx_buflen != buflen && con->rx_leftover <= buflen) {
         ret = con_realloc_receive_buf(con, buflen);
         if (ret < 0)
             goto out_resched;
     }
 
     for (;;) {
         /* calculate new buffer parameter regarding last receive and
          * possible leftover bytes
          */
         iov.iov_base = con->rx_buf + con->rx_leftover;
         iov.iov_len = con->rx_buflen - con->rx_leftover;
 
         memset(&msg, 0, sizeof(msg));
         msg.msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
         ret = kernel_recvmsg(con->sock, &msg, &iov, 1, iov.iov_len,
                      msg.msg_flags);
         trace_dlm_recv(con->nodeid, ret);
         if (ret == -EAGAIN)
             break;
         else if (ret <= 0)
             goto out_close;
 
         /* new buflen according readed bytes and leftover from last receive */
         buflen = ret + con->rx_leftover;
         ret = dlm_process_incoming_buffer(con->nodeid, con->rx_buf, buflen);
         if (ret < 0)
             goto out_close;
 
         /* calculate leftover bytes from process and put it into begin of
          * the receive buffer, so next receive we have the full message
          * at the start address of the receive buffer.
          */
         con->rx_leftover = buflen - ret;
         if (con->rx_leftover) {
             memmove(con->rx_buf, con->rx_buf + ret,
                 con->rx_leftover);
         }
     }
 
     dlm_midcomms_receive_done(con->nodeid);
     mutex_unlock(&con->sock_mutex);
     return 0;
 
 out_resched:
     if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
         queue_work(recv_workqueue, &con->rwork);
     mutex_unlock(&con->sock_mutex);
     return -EAGAIN;
 
 out_close:
     if (ret == 0) {
         log_print("connection %p got EOF from %d",
               con, con->nodeid);
 
         if (dlm_proto_ops->eof_condition &&
             dlm_proto_ops->eof_condition(con)) {
             set_bit(CF_EOF, &con->flags);
             mutex_unlock(&con->sock_mutex);
         } else {
             mutex_unlock(&con->sock_mutex);
             close_connection(con, false, true, false);
 
             /* handling for tcp shutdown */
             clear_bit(CF_SHUTDOWN, &con->flags);
             wake_up(&con->shutdown_wait);
         }
 
         /* signal to breaking receive worker */
         ret = -1;
     } else {
         mutex_unlock(&con->sock_mutex);
     }
     return ret;
 }
 
 /* Listening socket is busy, accept a connection */
 static int accept_from_sock(struct listen_connection *con)
 {
     int result;
     struct sockaddr_storage peeraddr;
     struct socket *newsock;
     int len, idx;
     int nodeid;
     struct connection *newcon;
     struct connection *addcon;
     unsigned int mark;
 
     if (!con->sock)
         return -ENOTCONN;
 
     result = kernel_accept(con->sock, &newsock, O_NONBLOCK);
     if (result < 0)
         goto accept_err;
 
     /* Get the connected socket's peer */
     memset(&peeraddr, 0, sizeof(peeraddr));
     len = newsock->ops->getname(newsock, (struct sockaddr *)&peeraddr, 2);
     if (len < 0) {
         result = -ECONNABORTED;
         goto accept_err;
     }
 
     /* Get the new node's NODEID */
     make_sockaddr(&peeraddr, 0, &len);
     if (addr_to_nodeid(&peeraddr, &nodeid, &mark)) {
         switch (peeraddr.ss_family) {
         case AF_INET: {
             struct sockaddr_in *sin = (struct sockaddr_in *)&peeraddr;
 
             log_print("connect from non cluster IPv4 node %pI4",
                   &sin->sin_addr);
             break;
         }
 #if IS_ENABLED(CONFIG_IPV6)
         case AF_INET6: {
             struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&peeraddr;
 
             log_print("connect from non cluster IPv6 node %pI6c",
                   &sin6->sin6_addr);
             break;
         }
 #endif
         default:
             log_print("invalid family from non cluster node");
             break;
         }
 
         sock_release(newsock);
         return -1;
     }
 
     log_print("got connection from %d", nodeid);
 
     /*  Check to see if we already have a connection to this node. This
      *  could happen if the two nodes initiate a connection at roughly
      *  the same time and the connections cross on the wire.
      *  In this case we store the incoming one in "othercon"
      */
     idx = srcu_read_lock(&connections_srcu);
     newcon = nodeid2con(nodeid, GFP_NOFS);
     if (!newcon) {
         srcu_read_unlock(&connections_srcu, idx);
         result = -ENOMEM;
         goto accept_err;
     }
 
     sock_set_mark(newsock->sk, mark);
 
     mutex_lock(&newcon->sock_mutex);
     if (newcon->sock) {
         struct connection *othercon = newcon->othercon;
 
         if (!othercon) {
             othercon = kzalloc(sizeof(*othercon), GFP_NOFS);
             if (!othercon) {
                 log_print("failed to allocate incoming socket");
                 mutex_unlock(&newcon->sock_mutex);
                 srcu_read_unlock(&connections_srcu, idx);
                 result = -ENOMEM;
                 goto accept_err;
             }
 
             result = dlm_con_init(othercon, nodeid);
             if (result < 0) {
                 kfree(othercon);
                 mutex_unlock(&newcon->sock_mutex);
                 srcu_read_unlock(&connections_srcu, idx);
                 goto accept_err;
             }
 
             lockdep_set_subclass(&othercon->sock_mutex, 1);
             set_bit(CF_IS_OTHERCON, &othercon->flags);
             newcon->othercon = othercon;
             othercon->sendcon = newcon;
         } else {
             /* close other sock con if we have something new */
             close_connection(othercon, false, true, false);
         }
 
         mutex_lock(&othercon->sock_mutex);
         add_sock(newsock, othercon);
         addcon = othercon;
         mutex_unlock(&othercon->sock_mutex);
     }
     else {
         /* accept copies the sk after we've saved the callbacks, so we
            don't want to save them a second time or comm errors will
            result in calling sk_error_report recursively. */
         add_sock(newsock, newcon);
         addcon = newcon;
     }
 
     set_bit(CF_CONNECTED, &addcon->flags);
     mutex_unlock(&newcon->sock_mutex);
 
     /*
      * Add it to the active queue in case we got data
      * between processing the accept adding the socket
      * to the read_sockets list
      */
     if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
         queue_work(recv_workqueue, &addcon->rwork);
 
     srcu_read_unlock(&connections_srcu, idx);
 
     return 0;
 
 accept_err:
     if (newsock)
         sock_release(newsock);
 
     if (result != -EAGAIN)
         log_print("error accepting connection from node: %d", result);
     return result;
 }
 
 /*
  * writequeue_entry_complete - try to delete and free write queue entry
  * @e: write queue entry to try to delete
  * @completed: bytes completed
  *
  * writequeue_lock must be held.
  */
 static void writequeue_entry_complete(struct writequeue_entry *e, int completed)
 {
     e->offset += completed;
     e->len -= completed;
     /* signal that page was half way transmitted */
     e->dirty = true;
 
     if (e->len == 0 && e->users == 0)
         free_entry(e);
 }
 
 /*
  * sctp_bind_addrs - bind a SCTP socket to all our addresses
  */
 static int sctp_bind_addrs(struct socket *sock, uint16_t port)
 {
     struct sockaddr_storage localaddr;
     struct sockaddr *addr = (struct sockaddr *)&localaddr;
     int i, addr_len, result = 0;
 
     for (i = 0; i < dlm_local_count; i++) {
         memcpy(&localaddr, dlm_local_addr[i], sizeof(localaddr));
         make_sockaddr(&localaddr, port, &addr_len);
 
         if (!i)
             result = kernel_bind(sock, addr, addr_len);
         else
             result = sock_bind_add(sock->sk, addr, addr_len);
 
         if (result < 0) {
             log_print("Can't bind to %d addr number %d, %d.\n",
                   port, i + 1, result);
             break;
         }
     }
     return result;
 }
 
 /* Get local addresses */
 static void init_local(void)
 {
     struct sockaddr_storage sas, *addr;
     int i;
 
     dlm_local_count = 0;
     for (i = 0; i < DLM_MAX_ADDR_COUNT; i++) {
         if (dlm_our_addr(&sas, i))
             break;
 
         addr = kmemdup(&sas, sizeof(*addr), GFP_NOFS);
         if (!addr)
             break;
         dlm_local_addr[dlm_local_count++] = addr;
     }
 }
 
 static void deinit_local(void)
 {
     int i;
 
     for (i = 0; i < dlm_local_count; i++)
         kfree(dlm_local_addr[i]);
 }
 
 static struct writequeue_entry *new_writequeue_entry(struct connection *con)
 {
     struct writequeue_entry *entry;
 
     entry = dlm_allocate_writequeue();
     if (!entry)
         return NULL;
 
     entry->page = alloc_page(GFP_ATOMIC | __GFP_ZERO);
     if (!entry->page) {
         dlm_free_writequeue(entry);
         return NULL;
     }
 
     entry->offset = 0;
     entry->len = 0;
     entry->end = 0;
     entry->dirty = false;
     entry->con = con;
     entry->users = 1;
     kref_init(&entry->ref);
     return entry;
 }
 
 static struct writequeue_entry *new_wq_entry(struct connection *con, int len,
                          char **ppc, void (*cb)(void *data),
                          void *data)
 {
     struct writequeue_entry *e;
 
     spin_lock(&con->writequeue_lock);
     if (!list_empty(&con->writequeue)) {
         e = list_last_entry(&con->writequeue, struct writequeue_entry, list);
         if (DLM_WQ_REMAIN_BYTES(e) >= len) {
             kref_get(&e->ref);
 
             *ppc = page_address(e->page) + e->end;
             if (cb)
                 cb(data);
 
             e->end += len;
             e->users++;
             goto out;
         }
     }
 
     e = new_writequeue_entry(con);
     if (!e)
         goto out;
 
     kref_get(&e->ref);
     *ppc = page_address(e->page);
     e->end += len;
     atomic_inc(&con->writequeue_cnt);
     if (cb)
         cb(data);
 
     list_add_tail(&e->list, &con->writequeue);
 
 out:
     spin_unlock(&con->writequeue_lock);
     return e;
 };
 
 static struct dlm_msg *dlm_lowcomms_new_msg_con(struct connection *con, int len,
                         gfp_t allocation, char **ppc,
                         void (*cb)(void *data),
                         void *data)
 {
     struct writequeue_entry *e;
     struct dlm_msg *msg;
 
     msg = dlm_allocate_msg(allocation);
     if (!msg)
         return NULL;
 
     kref_init(&msg->ref);
 
     e = new_wq_entry(con, len, ppc, cb, data);
     if (!e) {
         dlm_free_msg(msg);
         return NULL;
     }
 
     msg->retransmit = false;
     msg->orig_msg = NULL;
     msg->ppc = *ppc;
     msg->len = len;
     msg->entry = e;
 
     return msg;
 }
 
 /* avoid false positive for nodes_srcu, unlock happens in
  * dlm_lowcomms_commit_msg which is a must call if success
  */
 #ifndef __CHECKER__
 struct dlm_msg *dlm_lowcomms_new_msg(int nodeid, int len, gfp_t allocation,
                      char **ppc, void (*cb)(void *data),
                      void *data)
 {
     struct connection *con;
     struct dlm_msg *msg;
     int idx;
 
     if (len > DLM_MAX_SOCKET_BUFSIZE ||
         len < sizeof(struct dlm_header)) {
         BUILD_BUG_ON(PAGE_SIZE < DLM_MAX_SOCKET_BUFSIZE);
         log_print("failed to allocate a buffer of size %d", len);
         WARN_ON(1);
         return NULL;
     }
 
     idx = srcu_read_lock(&connections_srcu);
     con = nodeid2con(nodeid, allocation);
     if (!con) {
         srcu_read_unlock(&connections_srcu, idx);
         return NULL;
     }
 
     msg = dlm_lowcomms_new_msg_con(con, len, allocation, ppc, cb, data);
     if (!msg) {
         srcu_read_unlock(&connections_srcu, idx);
         return NULL;
     }
 
     /* we assume if successful commit must called */
     msg->idx = idx;
     return msg;
 }
 #endif
 
 static void _dlm_lowcomms_commit_msg(struct dlm_msg *msg)
 {
     struct writequeue_entry *e = msg->entry;
     struct connection *con = e->con;
     int users;
 
     spin_lock(&con->writequeue_lock);
     kref_get(&msg->ref);
     list_add(&msg->list, &e->msgs);
 
     users = --e->users;
     if (users)
         goto out;
 
     e->len = DLM_WQ_LENGTH_BYTES(e);
     spin_unlock(&con->writequeue_lock);
 
     queue_work(send_workqueue, &con->swork);
     return;
 
 out:
     spin_unlock(&con->writequeue_lock);
     return;
 }
 
 /* avoid false positive for nodes_srcu, lock was happen in
  * dlm_lowcomms_new_msg
  */
 #ifndef __CHECKER__
 void dlm_lowcomms_commit_msg(struct dlm_msg *msg)
 {
     _dlm_lowcomms_commit_msg(msg);
     srcu_read_unlock(&connections_srcu, msg->idx);
 }
 #endif
 
 void dlm_lowcomms_put_msg(struct dlm_msg *msg)
 {
     kref_put(&msg->ref, dlm_msg_release);
 }
 
 /* does not held connections_srcu, usage workqueue only */
 int dlm_lowcomms_resend_msg(struct dlm_msg *msg)
 {
     struct dlm_msg *msg_resend;
     char *ppc;
 
     if (msg->retransmit)
         return 1;
 
     msg_resend = dlm_lowcomms_new_msg_con(msg->entry->con, msg->len,
                           GFP_ATOMIC, &ppc, NULL, NULL);
     if (!msg_resend)
         return -ENOMEM;
 
     msg->retransmit = true;
     kref_get(&msg->ref);
     msg_resend->orig_msg = msg;
 
     memcpy(ppc, msg->ppc, msg->len);
     _dlm_lowcomms_commit_msg(msg_resend);
     dlm_lowcomms_put_msg(msg_resend);
 
     return 0;
 }
 
 /* Send a message */
 static void send_to_sock(struct connection *con)
 {
     const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
     struct writequeue_entry *e;
     int len, offset, ret;
     int count = 0;
 
     mutex_lock(&con->sock_mutex);
     if (con->sock == NULL)
         goto out_connect;
 
     spin_lock(&con->writequeue_lock);
     for (;;) {
         e = con_next_wq(con);
         if (!e)
             break;
 
         len = e->len;
         offset = e->offset;
         BUG_ON(len == 0 && e->users == 0);
         spin_unlock(&con->writequeue_lock);
 
         ret = kernel_sendpage(con->sock, e->page, offset, len,
                       msg_flags);
         trace_dlm_send(con->nodeid, ret);
         if (ret == -EAGAIN || ret == 0) {
             if (ret == -EAGAIN &&
                 test_bit(SOCKWQ_ASYNC_NOSPACE, &con->sock->flags) &&
                 !test_and_set_bit(CF_APP_LIMITED, &con->flags)) {
                 /* Notify TCP that we're limited by the
                  * application window size.
                  */
                 set_bit(SOCK_NOSPACE, &con->sock->flags);
                 con->sock->sk->sk_write_pending++;
             }
             cond_resched();
             goto out;
         } else if (ret < 0)
             goto out;
 
         /* Don't starve people filling buffers */
         if (++count >= MAX_SEND_MSG_COUNT) {
             cond_resched();
             count = 0;
         }
 
         spin_lock(&con->writequeue_lock);
         writequeue_entry_complete(e, ret);
     }
     spin_unlock(&con->writequeue_lock);
 
     /* close if we got EOF */
     if (test_and_clear_bit(CF_EOF, &con->flags)) {
         mutex_unlock(&con->sock_mutex);
         close_connection(con, false, false, true);
 
         /* handling for tcp shutdown */
         clear_bit(CF_SHUTDOWN, &con->flags);
         wake_up(&con->shutdown_wait);
     } else {
         mutex_unlock(&con->sock_mutex);
     }
 
     return;
 
 out:
     mutex_unlock(&con->sock_mutex);
     return;
 
 out_connect:
     mutex_unlock(&con->sock_mutex);
     queue_work(send_workqueue, &con->swork);
     cond_resched();
 }
 
 static void clean_one_writequeue(struct connection *con)
 {
     struct writequeue_entry *e, *safe;
 
     spin_lock(&con->writequeue_lock);
     list_for_each_entry_safe(e, safe, &con->writequeue, list) {
         free_entry(e);
     }
     spin_unlock(&con->writequeue_lock);
 }
 
 /* Called from recovery when it knows that a node has
    left the cluster */
 int dlm_lowcomms_close(int nodeid)
 {
     struct connection *con;
     struct dlm_node_addr *na;
     int idx;
 
     log_print("closing connection to node %d", nodeid);
     idx = srcu_read_lock(&connections_srcu);
     con = nodeid2con(nodeid, 0);
     if (con) {
         set_bit(CF_CLOSE, &con->flags);
         close_connection(con, true, true, true);
         clean_one_writequeue(con);
         if (con->othercon)
             clean_one_writequeue(con->othercon);
     }
     srcu_read_unlock(&connections_srcu, idx);
 
     spin_lock(&dlm_node_addrs_spin);
     na = find_node_addr(nodeid);
     if (na) {
         list_del(&na->list);
         while (na->addr_count--)
             kfree(na->addr[na->addr_count]);
         kfree(na);
     }
     spin_unlock(&dlm_node_addrs_spin);
 
     return 0;
 }
 
 /* Receive workqueue function */
 static void process_recv_sockets(struct work_struct *work)
 {
     struct connection *con = container_of(work, struct connection, rwork);
 
     clear_bit(CF_READ_PENDING, &con->flags);
     receive_from_sock(con);
 }
 
 static void process_listen_recv_socket(struct work_struct *work)
 {
     accept_from_sock(&listen_con);
 }
 
 static void dlm_connect(struct connection *con)
 {
     struct sockaddr_storage addr;
     int result, addr_len;
     struct socket *sock;
     unsigned int mark;
 
     /* Some odd races can cause double-connects, ignore them */
     if (con->retries++ > MAX_CONNECT_RETRIES)
         return;
 
     if (con->sock) {
         log_print("node %d already connected.", con->nodeid);
         return;
     }
 
     memset(&addr, 0, sizeof(addr));
     result = nodeid_to_addr(con->nodeid, &addr, NULL,
                 dlm_proto_ops->try_new_addr, &mark);
     if (result < 0) {
         log_print("no address for nodeid %d", con->nodeid);
         return;
     }
 
     /* Create a socket to communicate with */
     result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
                   SOCK_STREAM, dlm_proto_ops->proto, &sock);
     if (result < 0)
         goto socket_err;
 
     sock_set_mark(sock->sk, mark);
     dlm_proto_ops->sockopts(sock);
 
     add_sock(sock, con);
 
     result = dlm_proto_ops->bind(sock);
     if (result < 0)
         goto add_sock_err;
 
     log_print_ratelimited("connecting to %d", con->nodeid);
     make_sockaddr(&addr, dlm_config.ci_tcp_port, &addr_len);
     result = dlm_proto_ops->connect(con, sock, (struct sockaddr *)&addr,
                     addr_len);
     if (result < 0)
         goto add_sock_err;
 
     return;
 
 add_sock_err:
     dlm_close_sock(&con->sock);
 
 socket_err:
     /*
      * Some errors are fatal and this list might need adjusting. For other
      * errors we try again until the max number of retries is reached.
      */
     if (result != -EHOSTUNREACH &&
         result != -ENETUNREACH &&
         result != -ENETDOWN &&
         result != -EINVAL &&
         result != -EPROTONOSUPPORT) {
         log_print("connect %d try %d error %d", con->nodeid,
               con->retries, result);
         msleep(1000);
         lowcomms_connect_sock(con);
     }
 }
 
 /* Send workqueue function */
 static void process_send_sockets(struct work_struct *work)
 {
     struct connection *con = container_of(work, struct connection, swork);
 
     WARN_ON(test_bit(CF_IS_OTHERCON, &con->flags));
 
     clear_bit(CF_WRITE_PENDING, &con->flags);
 
     if (test_and_clear_bit(CF_RECONNECT, &con->flags)) {
         close_connection(con, false, false, true);
         dlm_midcomms_unack_msg_resend(con->nodeid);
     }
 
     if (con->sock == NULL) {
         if (test_and_clear_bit(CF_DELAY_CONNECT, &con->flags))
             msleep(1000);
 
         mutex_lock(&con->sock_mutex);
         dlm_connect(con);
         mutex_unlock(&con->sock_mutex);
     }
 
     if (!list_empty(&con->writequeue))
         send_to_sock(con);
 }
 
 static void work_stop(void)
 {
     if (recv_workqueue) {
         destroy_workqueue(recv_workqueue);
         recv_workqueue = NULL;
     }
 
     if (send_workqueue) {
         destroy_workqueue(send_workqueue);
         send_workqueue = NULL;
     }
 }
 
 static int work_start(void)
 {
     recv_workqueue = alloc_ordered_workqueue("dlm_recv", WQ_MEM_RECLAIM);
     if (!recv_workqueue) {
         log_print("can't start dlm_recv");
         return -ENOMEM;
     }
 
     send_workqueue = alloc_ordered_workqueue("dlm_send", WQ_MEM_RECLAIM);
     if (!send_workqueue) {
         log_print("can't start dlm_send");
         destroy_workqueue(recv_workqueue);
         recv_workqueue = NULL;
         return -ENOMEM;
     }
 
     return 0;
 }
 
 static void shutdown_conn(struct connection *con)
 {
     if (dlm_proto_ops->shutdown_action)
         dlm_proto_ops->shutdown_action(con);
 }
 
 void dlm_lowcomms_shutdown(void)
 {
     int idx;
 
     /* Set all the flags to prevent any
      * socket activity.
      */
     dlm_allow_conn = 0;
 
     if (recv_workqueue)
         flush_workqueue(recv_workqueue);
     if (send_workqueue)
         flush_workqueue(send_workqueue);
 
     dlm_close_sock(&listen_con.sock);
 
     idx = srcu_read_lock(&connections_srcu);
     foreach_conn(shutdown_conn);
     srcu_read_unlock(&connections_srcu, idx);
 }
 
 static void _stop_conn(struct connection *con, bool and_other)
 {
     mutex_lock(&con->sock_mutex);
     set_bit(CF_CLOSE, &con->flags);
     set_bit(CF_READ_PENDING, &con->flags);
     set_bit(CF_WRITE_PENDING, &con->flags);
     if (con->sock && con->sock->sk) {
         lock_sock(con->sock->sk);
         con->sock->sk->sk_user_data = NULL;
         release_sock(con->sock->sk);
     }
     if (con->othercon && and_other)
         _stop_conn(con->othercon, false);
     mutex_unlock(&con->sock_mutex);
 }
 
 static void stop_conn(struct connection *con)
 {
     _stop_conn(con, true);
 }
 
 static void connection_release(struct rcu_head *rcu)
 {
     struct connection *con = container_of(rcu, struct connection, rcu);
 
     kfree(con->rx_buf);
     kfree(con);
 }
 
 static void free_conn(struct connection *con)
 {
     close_connection(con, true, true, true);
     spin_lock(&connections_lock);
     hlist_del_rcu(&con->list);
     spin_unlock(&connections_lock);
     if (con->othercon) {
         clean_one_writequeue(con->othercon);
         call_srcu(&connections_srcu, &con->othercon->rcu,
               connection_release);
     }
     clean_one_writequeue(con);
     call_srcu(&connections_srcu, &con->rcu, connection_release);
 }
 
 static void work_flush(void)
 {
     int ok;
     int i;
     struct connection *con;
 
     do {
         ok = 1;
         foreach_conn(stop_conn);
         if (recv_workqueue)
             flush_workqueue(recv_workqueue);
         if (send_workqueue)
             flush_workqueue(send_workqueue);
         for (i = 0; i < CONN_HASH_SIZE && ok; i++) {
             hlist_for_each_entry_rcu(con, &connection_hash[i],
                          list) {
                 ok &= test_bit(CF_READ_PENDING, &con->flags);
                 ok &= test_bit(CF_WRITE_PENDING, &con->flags);
                 if (con->othercon) {
                     ok &= test_bit(CF_READ_PENDING,
                                &con->othercon->flags);
                     ok &= test_bit(CF_WRITE_PENDING,
                                &con->othercon->flags);
                 }
             }
         }
     } while (!ok);
 }
 
 void dlm_lowcomms_stop(void)
 {
     int idx;
 
     idx = srcu_read_lock(&connections_srcu);
     work_flush();
     foreach_conn(free_conn);
     srcu_read_unlock(&connections_srcu, idx);
     work_stop();
     deinit_local();
 
     dlm_proto_ops = NULL;
 }
 
 static int dlm_listen_for_all(void)
 {
     struct socket *sock;
     int result;
 
     log_print("Using %s for communications",
           dlm_proto_ops->name);
 
     result = dlm_proto_ops->listen_validate();
     if (result < 0)
         return result;
 
     result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
                   SOCK_STREAM, dlm_proto_ops->proto, &sock);
     if (result < 0) {
         log_print("Can't create comms socket: %d", result);
         return result;
     }
 
     sock_set_mark(sock->sk, dlm_config.ci_mark);
     dlm_proto_ops->listen_sockopts(sock);
 
     result = dlm_proto_ops->listen_bind(sock);
     if (result < 0)
         goto out;
 
     save_listen_callbacks(sock);
     add_listen_sock(sock, &listen_con);
 
     INIT_WORK(&listen_con.rwork, process_listen_recv_socket);
     result = sock->ops->listen(sock, 5);
     if (result < 0) {
         dlm_close_sock(&listen_con.sock);
         goto out;
     }
 
     return 0;
 
 out:
     sock_release(sock);
     return result;
 }
 
 static int dlm_tcp_bind(struct socket *sock)
 {
     struct sockaddr_storage src_addr;
     int result, addr_len;
 
     /* Bind to our cluster-known address connecting to avoid
      * routing problems.
      */
     memcpy(&src_addr, dlm_local_addr[0], sizeof(src_addr));
     make_sockaddr(&src_addr, 0, &addr_len);
 
     result = sock->ops->bind(sock, (struct sockaddr *)&src_addr,
                  addr_len);
     if (result < 0) {
         /* This *may* not indicate a critical error */
         log_print("could not bind for connect: %d", result);
     }
 
     return 0;
 }
 
 static int dlm_tcp_connect(struct connection *con, struct socket *sock,
                struct sockaddr *addr, int addr_len)
 {
     int ret;
 
     ret = sock->ops->connect(sock, addr, addr_len, O_NONBLOCK);
     switch (ret) {
     case -EINPROGRESS:
         fallthrough;
     case 0:
         return 0;
     }
 
     return ret;
 }
 
 static int dlm_tcp_listen_validate(void)
 {
     /* We don't support multi-homed hosts */
     if (dlm_local_count > 1) {
         log_print("TCP protocol can't handle multi-homed hosts, try SCTP");
         return -EINVAL;
     }
 
     return 0;
 }
 
 static void dlm_tcp_sockopts(struct socket *sock)
 {
     /* Turn off Nagle's algorithm */
     tcp_sock_set_nodelay(sock->sk);
 }
 
 static void dlm_tcp_listen_sockopts(struct socket *sock)
 {
     dlm_tcp_sockopts(sock);
     sock_set_reuseaddr(sock->sk);
 }
 
 static int dlm_tcp_listen_bind(struct socket *sock)
 {
     int addr_len;
 
     /* Bind to our port */
     make_sockaddr(dlm_local_addr[0], dlm_config.ci_tcp_port, &addr_len);
     return sock->ops->bind(sock, (struct sockaddr *)dlm_local_addr[0],
                    addr_len);
 }
 
 static const struct dlm_proto_ops dlm_tcp_ops = {
     .name = "TCP",
     .proto = IPPROTO_TCP,
     .connect = dlm_tcp_connect,
     .sockopts = dlm_tcp_sockopts,
     .bind = dlm_tcp_bind,
     .listen_validate = dlm_tcp_listen_validate,
     .listen_sockopts = dlm_tcp_listen_sockopts,
     .listen_bind = dlm_tcp_listen_bind,
     .shutdown_action = dlm_tcp_shutdown,
     .eof_condition = tcp_eof_condition,
 };
 
 static int dlm_sctp_bind(struct socket *sock)
 {
     return sctp_bind_addrs(sock, 0);
 }
 
 static int dlm_sctp_connect(struct connection *con, struct socket *sock,
                 struct sockaddr *addr, int addr_len)
 {
     int ret;
 
     /*
      * Make sock->ops->connect() function return in specified time,
      * since O_NONBLOCK argument in connect() function does not work here,
      * then, we should restore the default value of this attribute.
      */
     sock_set_sndtimeo(sock->sk, 5);
     ret = sock->ops->connect(sock, addr, addr_len, 0);
     sock_set_sndtimeo(sock->sk, 0);
     if (ret < 0)
         return ret;
 
     if (!test_and_set_bit(CF_CONNECTED, &con->flags))
         log_print("connected to node %d", con->nodeid);
 
     return 0;
 }
 
 static int dlm_sctp_listen_validate(void)
 {
     if (!IS_ENABLED(CONFIG_IP_SCTP)) {
         log_print("SCTP is not enabled by this kernel");
         return -EOPNOTSUPP;
     }
 
     request_module("sctp");
     return 0;
 }
 
 static int dlm_sctp_bind_listen(struct socket *sock)
 {
     return sctp_bind_addrs(sock, dlm_config.ci_tcp_port);
 }
 
 static void dlm_sctp_sockopts(struct socket *sock)
 {
     /* Turn off Nagle's algorithm */
     sctp_sock_set_nodelay(sock->sk);
     sock_set_rcvbuf(sock->sk, NEEDED_RMEM);
 }
 
 static const struct dlm_proto_ops dlm_sctp_ops = {
     .name = "SCTP",
     .proto = IPPROTO_SCTP,
     .try_new_addr = true,
     .connect = dlm_sctp_connect,
     .sockopts = dlm_sctp_sockopts,
     .bind = dlm_sctp_bind,
     .listen_validate = dlm_sctp_listen_validate,
     .listen_sockopts = dlm_sctp_sockopts,
     .listen_bind = dlm_sctp_bind_listen,
 };
 
 int dlm_lowcomms_start(void)
 {
     int error = -EINVAL;
     int i;
 
     for (i = 0; i < CONN_HASH_SIZE; i++)
         INIT_HLIST_HEAD(&connection_hash[i]);
 
     init_local();
     if (!dlm_local_count) {
         error = -ENOTCONN;
         log_print("no local IP address has been set");
         goto fail;
     }
 
     INIT_WORK(&listen_con.rwork, process_listen_recv_socket);
 
     error = work_start();
     if (error)
         goto fail_local;
 
     dlm_allow_conn = 1;
 
     /* Start listening */
     switch (dlm_config.ci_protocol) {
     case DLM_PROTO_TCP:
         dlm_proto_ops = &dlm_tcp_ops;
         break;
     case DLM_PROTO_SCTP:
         dlm_proto_ops = &dlm_sctp_ops;
         break;
     default:
         log_print("Invalid protocol identifier %d set",
               dlm_config.ci_protocol);
         error = -EINVAL;
         goto fail_proto_ops;
     }
 
     error = dlm_listen_for_all();
     if (error)
         goto fail_listen;
 
     return 0;
 
 fail_listen:
     dlm_proto_ops = NULL;
 fail_proto_ops:
     dlm_allow_conn = 0;
     dlm_close_sock(&listen_con.sock);
     work_stop();
 fail_local:
     deinit_local();
 fail:
     return error;
 }
 
 void dlm_lowcomms_exit(void)
 {
     struct dlm_node_addr *na, *safe;
 
     spin_lock(&dlm_node_addrs_spin);
     list_for_each_entry_safe(na, safe, &dlm_node_addrs, list) {
         list_del(&na->list);
         while (na->addr_count--)
             kfree(na->addr[na->addr_count]);
         kfree(na);
     }
     spin_unlock(&dlm_node_addrs_spin);
 }

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