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| author | Richard Cochran <rcochran@linutronix.de> | 2016-03-11 09:43:07 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2016-03-18 01:49:01 +0100 |
| commit | c75361c0b08a59d3c9863a5a673ae039d5118c35 (patch) | |
| tree | d406a57cfcbdf87374400d333f28dc47b064db05 | |
| parent | 4fec7ad5f637159525265a45f66482cf8817b45f (diff) | |
| download | op-kernel-dev-c75361c0b08a59d3c9863a5a673ae039d5118c35.zip op-kernel-dev-c75361c0b08a59d3c9863a5a673ae039d5118c35.tar.gz | |
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>
| -rw-r--r-- | drivers/cpufreq/cpufreq.c | 12 |
1 files changed, 10 insertions, 2 deletions
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 @@ 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) { |
