Commit 56d80622 authored Jan 24, 2017 by Jason Baron Committed by David S. Miller Jan 25, 2017

tcp: correct memory barrier usage in tcp_check_space()

sock_reset_flag() maps to __clear_bit() not the atomic version clear_bit().
Thus, we need smp_mb(), smp_mb__after_atomic() is not sufficient.

Fixes: 3c715127 ("tcp: add memory barriers to write space paths")
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 5207f399

net/ipv4/tcp_input.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -5078,7 +5078,7 @@ static void tcp_check_space(struct sock *sk)
		if (sock_flag(sk, SOCK_QUEUE_SHRUNK)) {
		sock_reset_flag(sk, SOCK_QUEUE_SHRUNK);
		/* pairs with tcp_poll() */
		smp_mb__after_atomic();
		smp_mb();
		if (sk->sk_socket &&
		test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
		tcp_new_space(sk);