Commit 3d476263 authored Apr 18, 2017 by Eric Dumazet Committed by David S. Miller Apr 20, 2017

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>

parent d02e93d6

net/ipv4/tcp_input.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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);
		}

		/*

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