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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 8FEBEC4321D for ; Mon, 20 Aug 2018 09:10:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 48F4F20C03 for ; Mon, 20 Aug 2018 09:10:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 48F4F20C03 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=rjwysocki.net 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 S1726237AbeHTMYz (ORCPT ); Mon, 20 Aug 2018 08:24:55 -0400 Received: from cloudserver094114.home.pl ([79.96.170.134]:55918 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726010AbeHTMYz (ORCPT ); Mon, 20 Aug 2018 08:24:55 -0400 Received: from 79.184.253.33.ipv4.supernova.orange.pl (79.184.253.33) (HELO aspire.rjw.lan) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83) id 46afced0d44f25f0; Mon, 20 Aug 2018 11:10:05 +0200 From: "Rafael J. Wysocki" To: Henry Willard Cc: viresh.kumar@linaro.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] cpufreq: governor: Protect cpufreq governor_data Date: Mon, 20 Aug 2018 11:07:49 +0200 Message-ID: <2923321.jmYcvy9DfS@aspire.rjw.lan> In-Reply-To: <1534291262-4207-1-git-send-email-henry.willard@oracle.com> References: <1534291262-4207-1-git-send-email-henry.willard@oracle.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday, August 15, 2018 2:01:02 AM CEST Henry Willard wrote: > If cppc_cpufreq.ko is deleted at the same time that tuned-adm is > changing profiles, there is a small chance that a race can occur > between cpufreq_dbs_governor_exit() and cpufreq_dbs_governor_limits() > resulting in a system failure when the latter tries to use > policy->governor_data that has been freed by the former. > > This patch uses gov_dbs_data_mutex to synchronize access. > > Signed-off-by: Henry Willard > --- > drivers/cpufreq/cpufreq_governor.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c > index 1d50e97d49f1..43416ee55849 100644 > --- a/drivers/cpufreq/cpufreq_governor.c > +++ b/drivers/cpufreq/cpufreq_governor.c > @@ -555,12 +555,20 @@ void cpufreq_dbs_governor_stop(struct cpufreq_policy *policy) > > void cpufreq_dbs_governor_limits(struct cpufreq_policy *policy) > { > - struct policy_dbs_info *policy_dbs = policy->governor_data; > + struct policy_dbs_info *policy_dbs; > + > + /* Protect gov->gdbs_data against cpufreq_dbs_governor_exit */ > + mutex_lock(&gov_dbs_data_mutex); > + policy_dbs = policy->governor_data; > + if (!policy_dbs) > + goto out; > > mutex_lock(&policy_dbs->update_mutex); > cpufreq_policy_apply_limits(policy); > gov_update_sample_delay(policy_dbs, 0); > > mutex_unlock(&policy_dbs->update_mutex); > +out: > + mutex_unlock(&gov_dbs_data_mutex); > } > EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_limits); > Applied, thanks!