From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757198Ab0EKOVP (ORCPT ); Tue, 11 May 2010 10:21:15 -0400 Received: from mx1.HRZ.Uni-Dortmund.DE ([129.217.128.51]:57696 "EHLO unimail.uni-dortmund.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751885Ab0EKOVN (ORCPT ); Tue, 11 May 2010 10:21:13 -0400 Message-ID: <4BE967B9.5050107@udo.edu> Date: Tue, 11 May 2010 16:20:41 +0200 From: Andrej Gelenberg User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100330 Shredder/3.0.4 MIME-Version: 1.0 To: linux@brodo.de, ashok.raj@intel.com, jacob.shin@amd.com CC: linux-kernel@vger.kernel.org, akpm@linux-foundation.org Subject: [PATCH] [CPUFREQ] fix race condition in store_scaling_governor Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Wrap store_scaling_governor with mutex lock cpufreq_governor_mutex. Fix kernel panic if switch scaling governor very fast. Bug in bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=15948 Signed-off-by: Andrej Gelenberg --- drivers/cpufreq/cpufreq.c | 16 +++++++++++----- 1 files changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 75d293e..6ba42f9 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -403,8 +403,6 @@ static int cpufreq_parse_governor(char *str_governor, unsigned int *policy, } else if (cpufreq_driver->target) { struct cpufreq_governor *t; - mutex_lock(&cpufreq_governor_mutex); - t = __find_governor(str_governor); if (t == NULL) { @@ -429,8 +427,6 @@ static int cpufreq_parse_governor(char *str_governor, unsigned int *policy, *governor = t; err = 0; } - - mutex_unlock(&cpufreq_governor_mutex); } out: return err; @@ -521,7 +517,7 @@ static ssize_t show_scaling_governor(struct cpufreq_policy *policy, char *buf) /** * store_scaling_governor - store policy for the specified CPU */ -static ssize_t store_scaling_governor(struct cpufreq_policy *policy, +static ssize_t _store_scaling_governor(struct cpufreq_policy *policy, const char *buf, size_t count) { unsigned int ret = -EINVAL; @@ -553,6 +549,16 @@ static ssize_t store_scaling_governor(struct cpufreq_policy *policy, return count; } +static ssize_t store_scaling_governor(struct cpufreq_policy *policy, + const char *buf, size_t count) +{ + ssize_t ret; + mutex_lock(&cpufreq_governor_mutex); + ret = _store_scaling_governor(policy, buf, count); + mutex_unlock(&cpufreq_governor_mutex); + return ret; +} + /** * show_scaling_driver - show the cpufreq driver currently loaded */ -- 1.7.1