linux-kernel - [PATCH] cpufreq: Call __cpufreq_governor() with correct policy->cpus mask

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <e3001264b4d7328b41130857adbb51e93d224c26.1365667475.git.viresh.kumar@linaro.org>
Date:	Thu, 11 Apr 2013 13:34:53 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	rjw@...k.pl
Cc:	cpufreq@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, robin.randhawa@....com,
	Steve.Bannister@....com, Liviu.Dudau@....com,
	charles.garcia-tobin@....com, arvind.chauhan@....com,
	linaro-kernel@...ts.linaro.org, patches@...aro.org,
	Viresh Kumar <viresh.kumar@...aro.org>
Subject: [PATCH] cpufreq: Call __cpufreq_governor() with correct policy->cpus mask

__cpufreq_governor() must be called with correct policy->cpus mask. In
__cpufreq_remove_dev() we initially clear policy->cpus with cpumask_clear_cpu()
and then call __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT). In case
governor is doing some per-cpu stuff in EXIT callback, this can create uncertain
behavior.

Generic governors in drivers/cpufreq/ doesn't do any per-cpu stuff in EXIT
callback and so we don't face any issues currently. But its better to keep the
code clean, so we don't face any issues in future.

Now, we call cpumask_clear_cpu() only when multiple cpus are managed by policy.

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/cpufreq/cpufreq.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index fd97a62..3564947 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1105,7 +1105,9 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
 
 	WARN_ON(lock_policy_rwsem_write(cpu));
 	cpus = cpumask_weight(data->cpus);
-	cpumask_clear_cpu(cpu, data->cpus);
+
+	if (cpus > 1)
+		cpumask_clear_cpu(cpu, data->cpus);
 	unlock_policy_rwsem_write(cpu);
 
 	if (cpu != data->cpu) {
-- 
1.7.12.rc2.18.g61b472e

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/