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tcp: Fix race in tcp_poll

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If a RST comes in immediately after checking sk->sk_err, tcp_poll will
return POLLIN but not POLLOUT.  Fix this by checking sk->sk_err at the end
of tcp_poll.  Additionally, ensure the correct order of operations on SMP
machines with memory barriers.

Signed-off-by: Tom Marshall <tdm.code@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tom Marshall
2010-09-20 15:42:05 -07:00
committed by David S. Miller
parent 9828e6e6e3
commit a4d258036e
2 changed files with 7 additions and 2 deletions
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2
net/ipv4/tcp_input.c
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@@ -4048,6 +4048,8 @@ static void tcp_reset(struct sock *sk)
default:
sk->sk_err = ECONNRESET;
}
/* This barrier is coupled with smp_rmb() in tcp_poll() */
smp_wmb();
if (!sock_flag(sk, SOCK_DEAD))
sk->sk_error_report(sk);