tcp: do not lock listener to process SYN packets

[deliverable/linux.git] / net / ipv4 / tcp_ipv4.c

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index ac2ea73e9aafcdd2040b374a3b218d7bed07b614..34310748a36554a4ca6cfdd733e5844a04d992d0 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1355,7 +1355,7 @@ static struct sock *tcp_v4_cookie_check(struct sock *sk, struct sk_buff *skb)
 }
 
 /* The socket must have it's spinlock held when we get
- * here.
+ * here, unless it is a TCP_LISTEN socket.
  *
  * We have a potential double-lock case here, so even when
  * doing backlog processing we use the BH locking scheme.
@@ -1619,9 +1619,15 @@ process:
        if (sk_filter(sk, skb))
                goto discard_and_relse;
 
-       sk_incoming_cpu_update(sk);
        skb->dev = NULL;
 
+       if (sk->sk_state == TCP_LISTEN) {
+               ret = tcp_v4_do_rcv(sk, skb);
+               goto put_and_return;
+       }
+
+       sk_incoming_cpu_update(sk);
+
        bh_lock_sock_nested(sk);
        tcp_sk(sk)->segs_in += max_t(u16, 1, skb_shinfo(skb)->gso_segs);
        ret = 0;
@@ -1636,6 +1642,7 @@ process:
        }
        bh_unlock_sock(sk);
 
+put_and_return:
        sock_put(sk);
 
        return ret;