From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756600Ab3HFR0D (ORCPT ); Tue, 6 Aug 2013 13:26:03 -0400 Received: from mail-pb0-f51.google.com ([209.85.160.51]:57742 "EHLO mail-pb0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756492Ab3HFRYf (ORCPT ); Tue, 6 Aug 2013 13:24:35 -0400 From: Viresh Kumar To: rjw@sisk.pl Cc: linaro-kernel@lists.linaro.org, patches@linaro.org, cpufreq@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, srivatsa.bhat@linux.vnet.ibm.com, Viresh Kumar Subject: [PATCH V2 08/11] cpufreq: Fix broken usage of governor->owner's refcount Date: Tue, 6 Aug 2013 22:53:10 +0530 Message-Id: <28d948514a30b279afb99ff156bc3a3f74234641.1375809311.git.viresh.kumar@linaro.org> X-Mailer: git-send-email 1.7.12.rc2.18.g61b472e In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Governor's owner refcount usage was broken. We should increment refcount only when CPUFREQ_GOV_POLICY_INIT event has come and should decrement only if CPUFREQ_GOV_POLICY_EXIT has come. Currently there can be situations where governor is in use but we have allowed it to be unloaded which may result in undefined behavior. Lets fix it. Signed-off-by: Viresh Kumar --- drivers/cpufreq/cpufreq.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index fe04b79..62eddb6 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1708,8 +1708,9 @@ static int __cpufreq_governor(struct cpufreq_policy *policy, } } - if (!try_module_get(policy->governor->owner)) - return -EINVAL; + if (event == CPUFREQ_GOV_POLICY_INIT) + if (!try_module_get(policy->governor->owner)) + return -EINVAL; pr_debug("__cpufreq_governor for CPU %u, event %u\n", policy->cpu, event); @@ -1718,6 +1719,8 @@ static int __cpufreq_governor(struct cpufreq_policy *policy, if ((!policy->governor_enabled && (event == CPUFREQ_GOV_STOP)) || (policy->governor_enabled && (event == CPUFREQ_GOV_START))) { mutex_unlock(&cpufreq_governor_lock); + if (event == CPUFREQ_GOV_POLICY_INIT) + module_put(policy->governor->owner); return -EBUSY; } @@ -1745,11 +1748,8 @@ static int __cpufreq_governor(struct cpufreq_policy *policy, mutex_unlock(&cpufreq_governor_lock); } - /* we keep one module reference alive for - each CPU governed by this CPU */ - if ((event != CPUFREQ_GOV_START) || ret) - module_put(policy->governor->owner); - if ((event == CPUFREQ_GOV_STOP) && !ret) + if (((event == CPUFREQ_GOV_POLICY_INIT) && ret) || + ((event == CPUFREQ_GOV_POLICY_EXIT) && !ret)) module_put(policy->governor->owner); return ret; -- 1.7.12.rc2.18.g61b472e