From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4D1B5C33CB6 for ; Thu, 16 Jan 2020 17:30:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1A12724716 for ; Thu, 16 Jan 2020 17:30:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579195812; bh=4yi/VfKsIAwD+kVuskrVQiWDYeWK1KPjwiFrid/OIkk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=jX1FxN6I7/JSex4UWO0MHdGtAkeyWww5LBFbjhQKA7WvFNIBl9RGPME/2JrpxGEu4 kY7Bj6an19UnjTSIDqo7x1zBr0ZtQL66aEA6KSvm6CSYiYMcKhLtGYYTMUkuHVABy8 cv8wgvrgLOHp10M9gM7vJdEu68suxZEVL1boTwOQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404327AbgAPRaK (ORCPT ); Thu, 16 Jan 2020 12:30:10 -0500 Received: from mail.kernel.org ([198.145.29.99]:42384 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392968AbgAPRaH (ORCPT ); Thu, 16 Jan 2020 12:30:07 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1F2B724727; Thu, 16 Jan 2020 17:30:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579195806; bh=4yi/VfKsIAwD+kVuskrVQiWDYeWK1KPjwiFrid/OIkk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Xyx+c/JkDpm2Yh2DH/GvP1NaNKZZ9B8MUK4/ZA7VMGj8Rbdf8LNmQFokpZstVi5/U 1pf4C+tNR4w4YUwsPEg+PQs5m5cbX23e1+rV5qa+YGuMO8WSQQWgGVKd88inTeWCco RkdnN0QiNcF1TFugWV3gXpGCrGuUJh2KIFKD2Qww= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Eric Dumazet , Jakub Kicinski , Sasha Levin , netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 320/371] tcp: annotate lockless access to tcp_memory_pressure Date: Thu, 16 Jan 2020 12:23:12 -0500 Message-Id: <20200116172403.18149-263-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200116172403.18149-1-sashal@kernel.org> References: <20200116172403.18149-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Eric Dumazet [ Upstream commit 1f142c17d19a5618d5a633195a46f2c8be9bf232 ] tcp_memory_pressure is read without holding any lock, and its value could be changed on other cpus. Use READ_ONCE() to annotate these lockless reads. The write side is already using atomic ops. Fixes: b8da51ebb1aa ("tcp: introduce tcp_under_memory_pressure()") Signed-off-by: Eric Dumazet Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- include/net/tcp.h | 2 +- net/ipv4/tcp.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 00d10f0e1194..c96302310314 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -289,7 +289,7 @@ static inline bool tcp_under_memory_pressure(const struct sock *sk) mem_cgroup_under_socket_pressure(sk->sk_memcg)) return true; - return tcp_memory_pressure; + return READ_ONCE(tcp_memory_pressure); } /* * The next routines deal with comparing 32 bit unsigned ints diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 8f07655718f3..db1eceda2359 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -328,7 +328,7 @@ void tcp_enter_memory_pressure(struct sock *sk) { unsigned long val; - if (tcp_memory_pressure) + if (READ_ONCE(tcp_memory_pressure)) return; val = jiffies; @@ -343,7 +343,7 @@ void tcp_leave_memory_pressure(struct sock *sk) { unsigned long val; - if (!tcp_memory_pressure) + if (!READ_ONCE(tcp_memory_pressure)) return; val = xchg(&tcp_memory_pressure, 0); if (val) -- 2.20.1