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cpufreq: interactive: fix race on cpufreq TRANSITION notifier

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The cpufreq TRANSTION notifier callback does not check the
governor_enabled state on affected CPUS, which will case
kernel panic in update_load because the policy object maybe
NULL or invalid when governor_enabled is false.

Change-Id: Ie0f1718124f61e2f9b5da57abc6981ada5b83908
Signed-off-by: Lianwei Wang <a22439@motorola.com>
This commit is contained in:
Lianwei Wang 2013-05-16 12:07:23 +08:00 • committed by John Stultz
parent 83720c33a9
commit 7a5c8bae5c
1 changed files with 10 additions and 0 deletions
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10
drivers/cpufreq/cpufreq_interactive.c
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@ -634,9 +634,19 @@ static int cpufreq_interactive_notifier(
for_each_cpu(cpu, pcpu->policy->cpus) {
struct cpufreq_interactive_cpuinfo *pjcpu =
&per_cpu(cpuinfo, cpu);
if (cpu != freq->cpu) {
if (!down_read_trylock(&pjcpu->enable_sem))
continue;
if (!pjcpu->governor_enabled) {
up_read(&pjcpu->enable_sem);
continue;
}
}
spin_lock_irqsave(&pjcpu->load_lock, flags);
update_load(cpu);
spin_unlock_irqrestore(&pjcpu->load_lock, flags);
if (cpu != freq->cpu)
up_read(&pjcpu->enable_sem);
}
up_read(&pcpu->enable_sem);