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cpufreq: Make cpufreq_quick_get() safe to call 

The function, cpufreq_quick_get, accesses the global 'cpufreq_driver' and
its fields without taking the associated lock, cpufreq_driver_lock.

Without the locking, nothing guarantees that 'cpufreq_driver' remains
consistent during the call.  This patch fixes the issue by taking the lock
before accessing the data structure.

Signed-off-by: Richard Cochran <rcochran@linutronix.de>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Richard Cochran 2016-03-11 09:43:07 +01:00 committed by Rafael J. Wysocki
parent 4fec7ad5f6
commit c75361c0b0
1 changed files with 10 additions and 2 deletions
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12
drivers/cpufreq/cpufreq.c
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@ -1401,9 +1401,17 @@ unsigned int cpufreq_quick_get(unsigned int cpu)
{
struct cpufreq_policy *policy;
unsigned int ret_freq = 0;
unsigned long flags;
if (cpufreq_driver && cpufreq_driver->setpolicy && cpufreq_driver->get)
return cpufreq_driver->get(cpu);
read_lock_irqsave(&cpufreq_driver_lock, flags);
if (cpufreq_driver && cpufreq_driver->setpolicy && cpufreq_driver->get) {
ret_freq = cpufreq_driver->get(cpu);
read_unlock_irqrestore(&cpufreq_driver_lock, flags);
return ret_freq;
}
read_unlock_irqrestore(&cpufreq_driver_lock, flags);
policy = cpufreq_cpu_get(cpu);
if (policy) {