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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 51895C2D0DB for ; Fri, 24 Jan 2020 11:35:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 20671222D9 for ; Fri, 24 Jan 2020 11:35:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579865703; bh=B8Sf/ztuwijQujQ65GBe6GFH4/Czinnh5+RDWtZNTGY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=dB8L3LyveZT/ySlNQlMXASllEPGRsVlPf+PZNJB1pbUmPlCg3k4j5Fl8BcZzfOZu4 R00W6TjvmDUxLoxYgxG9cUsrgaiIxuIpGRP3PZuc3e4KakJlJFmNX4lQ/HzBs+3A66 CM4WluWk8JV1fUBfMozw2a7gP4Nn2cStTw6TMEfg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404786AbgAXLfB (ORCPT ); Fri, 24 Jan 2020 06:35:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:54902 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391908AbgAXLe5 (ORCPT ); Fri, 24 Jan 2020 06:34:57 -0500 Received: from localhost (ip-213-127-102-57.ip.prioritytelecom.net [213.127.102.57]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BBEB722527; Fri, 24 Jan 2020 11:34:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579865696; bh=B8Sf/ztuwijQujQ65GBe6GFH4/Czinnh5+RDWtZNTGY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=16wabLKsnGkv6zQVKB1HncaPhIm26cxA0ng6eJCbBlKrIs6Z7agY9FgPR2yKo6q+/ 89tqrSVePdlJlcC6TazVINQwds7L9hYFGaovNxh+bEAWkMk81Tq9wjzhcSHT7E/cVT uDRiD7z/DdP0tQeNSJtz3m38NskHA/gCKmATW/SM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Jakub Kicinski , Sasha Levin Subject: [PATCH 4.19 601/639] tcp: annotate lockless access to tcp_memory_pressure Date: Fri, 24 Jan 2020 10:32:51 +0100 Message-Id: <20200124093204.662654132@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200124093047.008739095@linuxfoundation.org> References: <20200124093047.008739095@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 ac4ffe8013d8a..918bfd0d7d1f9 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -261,7 +261,7 @@ 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 cd8a92e7a39eb..af9361eba64a6 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -325,7 +325,7 @@ void tcp_enter_memory_pressure(struct sock *sk) { unsigned long val; - if (tcp_memory_pressure) + if (READ_ONCE(tcp_memory_pressure)) return; val = jiffies; @@ -340,7 +340,7 @@ 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