4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Jason Baron <jba...@akamai.com> [ Upstream commit 56d806222ace4c3aeae516cd7a855340fb2839d8 ] 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: 3c7151275c0c ("tcp: add memory barriers to write space paths") Cc: Eric Dumazet <eric.duma...@gmail.com> Cc: Oleg Nesterov <o...@redhat.com> Signed-off-by: Jason Baron <jba...@akamai.com> Acked-by: Eric Dumazet <eduma...@google.com> Reported-by: Oleg Nesterov <o...@redhat.com> Signed-off-by: David S. Miller <da...@davemloft.net> Signed-off-by: Sasha Levin <alexander.le...@verizon.com> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- net/ipv4/tcp_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4942,7 +4942,7 @@ static void tcp_check_space(struct sock 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);