3 files changed, 24 insertions, 2 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index 3df778ccaa82..1dbb1f9f7c1b 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -926,6 +926,17 @@ void sk_stream_kill_queues(struct sock *sk);
 void sk_set_memalloc(struct sock *sk);
 void sk_clear_memalloc(struct sock *sk);
 
+void __sk_flush_backlog(struct sock *sk);
+
+static inline bool sk_flush_backlog(struct sock *sk)
+{
+        if (unlikely(READ_ONCE(sk->sk_backlog.tail))) {
+                __sk_flush_backlog(sk);
+                return true;
+        }
+        return false;
+}
+
 int sk_wait_data(struct sock *sk, long *timeo, const struct sk_buff *skb);
 
 struct request_sock_ops;
diff --git a/net/core/sock.c b/net/core/sock.c
index 70744dbb6c3f..f615e9391170 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2048,6 +2048,13 @@ static void __release_sock(struct sock *sk)
         sk->sk_backlog.len = 0;
 }
 
+void __sk_flush_backlog(struct sock *sk)
+{
+        spin_lock_bh(&sk->sk_lock.slock);
+        __release_sock(sk);
+        spin_unlock_bh(&sk->sk_lock.slock);
+}
+
 /**
  * sk_wait_data - wait for data to arrive at sk_receive_queue
  * @sk:    sock to wait on
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 4787f86ae64c..b945c2b046c5 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1136,11 +1136,12 @@ int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
         /* This should be in poll */
         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 
-        mss_now = tcp_send_mss(sk, &size_goal, flags);
-
         /* Ok commence sending. */
         copied = 0;
 
+restart:
+        mss_now = tcp_send_mss(sk, &size_goal, flags);
+
         err = -EPIPE;
         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
                 goto out_err;
@@ -1166,6 +1167,9 @@ new_segment:
                         if (!sk_stream_memory_free(sk))
                                 goto wait_for_sndbuf;
 
+                        if (sk_flush_backlog(sk))
+                                goto restart;
+
                         skb = sk_stream_alloc_skb(sk,
                                                   select_size(sk, sg),
                                                   sk->sk_allocation,