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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 D1AF9C1B0F2 for ; Wed, 20 Jun 2018 09:06:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8FA3620846 for ; Wed, 20 Jun 2018 09:06:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8FA3620846 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932519AbeFTJG4 (ORCPT ); Wed, 20 Jun 2018 05:06:56 -0400 Received: from foss.arm.com ([217.140.101.70]:34018 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754813AbeFTJGu (ORCPT ); Wed, 20 Jun 2018 05:06:50 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id AE2311682; Wed, 20 Jun 2018 02:06:50 -0700 (PDT) Received: from e105550-lin.cambridge.arm.com (e105550-lin.cambridge.arm.com [10.1.211.30]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 36D893F246; Wed, 20 Jun 2018 02:06:49 -0700 (PDT) From: Morten Rasmussen To: peterz@infradead.org, mingo@redhat.com Cc: valentin.schneider@arm.com, dietmar.eggemann@arm.com, vincent.guittot@linaro.org, gaku.inami.xh@renesas.com, linux-kernel@vger.kernel.org, Morten Rasmussen Subject: [PATCHv3 7/9] sched: Wrap rq->rd->overload accesses with READ/WRITE_ONCE Date: Wed, 20 Jun 2018 10:05:47 +0100 Message-Id: <1529485549-5191-8-git-send-email-morten.rasmussen@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1529485549-5191-1-git-send-email-morten.rasmussen@arm.com> References: <1529485549-5191-1-git-send-email-morten.rasmussen@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Valentin Schneider This variable can be read and set locklessly within update_sd_lb_stats(). As such, READ/WRITE_ONCE are added to make sure nothing terribly wrong can happen because of the compiler. cc: Ingo Molnar cc: Peter Zijlstra Signed-off-by: Valentin Schneider Signed-off-by: Morten Rasmussen --- kernel/sched/fair.c | 6 +++--- kernel/sched/sched.h | 4 ++-- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 545fa3600894..9dd147c71dd0 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8431,8 +8431,8 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd if (!env->sd->parent) { /* update overload indicator if we are at root domain */ - if (env->dst_rq->rd->overload != overload) - env->dst_rq->rd->overload = overload; + if (READ_ONCE(env->dst_rq->rd->overload) != overload) + WRITE_ONCE(env->dst_rq->rd->overload, overload); } } @@ -9875,7 +9875,7 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf) rq_unpin_lock(this_rq, rf); if (this_rq->avg_idle < sysctl_sched_migration_cost || - !this_rq->rd->overload) { + !READ_ONCE(this_rq->rd->overload)) { rcu_read_lock(); sd = rcu_dereference_check_sched_domain(this_rq->sd); diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index f945edadd2c5..791d9badad31 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1665,8 +1665,8 @@ static inline void add_nr_running(struct rq *rq, unsigned count) if (prev_nr < 2 && rq->nr_running >= 2) { #ifdef CONFIG_SMP - if (!rq->rd->overload) - rq->rd->overload = 1; + if (!READ_ONCE(rq->rd->overload)) + WRITE_ONCE(rq->rd->overload, 1); #endif } -- 2.7.4