| From | Bálint Czobor <> | Subject | [PATCH 50/70] cpufreq: interactive: fix race on cpufreq TRANSITION notifier | Date | Tue, 27 Oct 2015 18:30:38 +0100 |
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From: Lianwei Wang <a22439@motorola.com>
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> Signed-off-by: Bálint Czobor <czoborbalint@gmail.com> --- drivers/cpufreq/cpufreq_interactive.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/drivers/cpufreq/cpufreq_interactive.c b/drivers/cpufreq/cpufreq_interactive.c index 7303f50..691923d 100644 --- a/drivers/cpufreq/cpufreq_interactive.c +++ b/drivers/cpufreq/cpufreq_interactive.c @@ -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); -- 1.7.9.5
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