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=-15.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,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 C921BC33CAF for ; Thu, 16 Jan 2020 17:34:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 98CD0246A1 for ; Thu, 16 Jan 2020 17:34:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579196086; bh=tO9+NvN2CHz+pMQCJlzm6srVxp0TIkGcSiB03L9otBA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=eUIZOaexx8Xmgk+FFRvHwBKsiXIE3LM2fUKYvdWtlNzMmqajgYKBevNvf+QCxRNkg BMJrsWE4M5ug5MeEkdsTTCcGR2EibsLruaY+X8cLy83H85A9d1qPe8CeGg/DYrFIvB AiL+Fpqws025poDkg7q+xPPFNIDVaH4O2AKacJU4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393017AbgAPRep (ORCPT ); Thu, 16 Jan 2020 12:34:45 -0500 Received: from mail.kernel.org ([198.145.29.99]:42302 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392946AbgAPRaE (ORCPT ); Thu, 16 Jan 2020 12:30:04 -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 56E7424714; Thu, 16 Jan 2020 17:30:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579195804; bh=tO9+NvN2CHz+pMQCJlzm6srVxp0TIkGcSiB03L9otBA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZBnNZQ9cAKG0BNNHU6cItUbCcKa8wO0YS4gNDDH2hfF/lTxCrlp0G4cUdhpDA/NGG Om4efV2xfN5nDRuCI4ZTAugI48UC1eWn9jZTPHa+75C7nMf9aAb67Ph1ryNkg6X7eW lvBCIxJxKu052ePwfTT9PEFovjKw7gY/6OC2vBC0= 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 4.14 318/371] net: avoid possible false sharing in sk_leave_memory_pressure() Date: Thu, 16 Jan 2020 12:23:10 -0500 Message-Id: <20200116172403.18149-261-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: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Dumazet [ Upstream commit 503978aca46124cd714703e180b9c8292ba50ba7 ] As mentioned in https://github.com/google/ktsan/wiki/READ_ONCE-and-WRITE_ONCE#it-may-improve-performance a C compiler can legally transform : if (memory_pressure && *memory_pressure) *memory_pressure = 0; to : if (memory_pressure) *memory_pressure = 0; Fixes: 0604475119de ("tcp: add TCPMemoryPressuresChrono counter") Fixes: 180d8cd942ce ("foundations of per-cgroup memory pressure controlling.") Fixes: 3ab224be6d69 ("[NET] CORE: Introducing new memory accounting interface.") Signed-off-by: Eric Dumazet Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/core/sock.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/core/sock.c b/net/core/sock.c index 90ccbbf9e6b0..03ca2f638eb4 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2165,8 +2165,8 @@ static void sk_leave_memory_pressure(struct sock *sk) } else { unsigned long *memory_pressure = sk->sk_prot->memory_pressure; - if (memory_pressure && *memory_pressure) - *memory_pressure = 0; + if (memory_pressure && READ_ONCE(*memory_pressure)) + WRITE_ONCE(*memory_pressure, 0); } } -- 2.20.1