Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754971AbdLGNJD (ORCPT ); Thu, 7 Dec 2017 08:09:03 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:33726 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932222AbdLGNJA (ORCPT ); Thu, 7 Dec 2017 08:09:00 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Oleg Nesterov , Jason Baron , Eric Dumazet , "David S. Miller" , Sasha Levin Subject: [PATCH 4.4 36/49] tcp: correct memory barrier usage in tcp_check_space() Date: Thu, 7 Dec 2017 14:07:30 +0100 Message-Id: <20171207124708.775997948@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171207124703.742654162@linuxfoundation.org> References: <20171207124703.742654162@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1258 Lines: 37 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jason Baron [ 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 Cc: Oleg Nesterov Signed-off-by: Jason Baron Acked-by: Eric Dumazet Reported-by: Oleg Nesterov Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- 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);