From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viresh Kumar Subject: [PATCH V5 06/14] cpufreq: Mark policy->governor = NULL for inactive policies Date: Mon, 18 May 2015 10:43:29 +0530 Message-ID: References: Return-path: Received: from mail-pd0-f182.google.com ([209.85.192.182]:36662 "EHLO mail-pd0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751148AbbERFON (ORCPT ); Mon, 18 May 2015 01:14:13 -0400 Received: by pdfh10 with SMTP id h10so133406876pdf.3 for ; Sun, 17 May 2015 22:14:13 -0700 (PDT) In-Reply-To: In-Reply-To: References: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Rafael Wysocki Cc: linaro-kernel@lists.linaro.org, linux-pm@vger.kernel.org, sboyd@codeaurora.org, prarit@redhat.com, skannan@codeaurora.org, Srivatsa Bhat , Viresh Kumar Later commits would change the way policies are managed today. Policies wouldn't be freed on cpu hotplug (currently they aren't freed on suspend), and while the CPU is offline, the sysfs cpufreq files would still be present. Because we don't mark policy->governor as NULL, it still contains pointer of the last used governor. And if the governor is removed, while all the CPUs of a policy are hotplugged out, this pointer wouldn't be valid anymore. And if we try to read the 'scaling_governor', etc. from sysfs, it will result in kernel OOPs. To prevent this, mark policy->governor as NULL for all inactive policies while the governor is removed from kernel. Signed-off-by: Viresh Kumar --- drivers/cpufreq/cpufreq.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 16275ba6428e..c08de5e985c7 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1083,7 +1083,6 @@ static struct cpufreq_policy *cpufreq_policy_restore(unsigned int cpu) if (likely(policy)) { /* Policy should be inactive here */ WARN_ON(!policy_is_inactive(policy)); - policy->governor = NULL; } return policy; @@ -2145,8 +2144,10 @@ void cpufreq_unregister_governor(struct cpufreq_governor *governor) /* clear last_governor for all inactive policies */ read_lock_irqsave(&cpufreq_driver_lock, flags); for_each_inactive_policy(policy) { - if (!strcmp(policy->last_governor, governor->name)) + if (!strcmp(policy->last_governor, governor->name)) { + policy->governor = NULL; strcpy(policy->last_governor, "\0"); + } } read_unlock_irqrestore(&cpufreq_driver_lock, flags); -- 2.4.0