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>
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 4c78258..f870399 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1401,9 +1401,17 @@
{
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) {