From 3d4762639dd36a5f0f433f0c9d82e9743dc21a33 Mon Sep 17 00:00:00 2001 From: Eric Dumazet <edumazet@google.com> Date: Tue, 18 Apr 2017 09:45:51 -0700 Subject: [PATCH] tcp: remove poll() flakes when receiving RST When a RST packet is processed, we send two wakeup events to interested polling users. First one by a sk->sk_error_report(sk) from tcp_reset(), followed by a sk->sk_state_change(sk) from tcp_done(). Depending on machine load and luck, poll() can either return POLLERR, or POLLIN|POLLOUT|POLLERR|POLLHUP (this happens on 99 % of the cases) This is probably fine, but we can avoid the confusion by reordering things so that we have more TCP fields updated before the first wakeup. This might even allow us to remove some barriers we added in the past. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> --- net/ipv4/tcp_input.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index a5838858c362c..37e2aa925f623 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4008,10 +4008,10 @@ void tcp_reset(struct sock *sk) /* This barrier is coupled with smp_rmb() in tcp_poll() */ smp_wmb(); + tcp_done(sk); + if (!sock_flag(sk, SOCK_DEAD)) sk->sk_error_report(sk); - - tcp_done(sk); } /* -- GitLab