Commit 41682032 authored Oct 31, 2012 by Daniel Lezcano Committed by Rafael J. Wysocki Nov 15, 2012

cpuidle: move driver checking within the lock section



The code is racy and the check with cpuidle_curr_driver should be
done under the lock.

I don't find a path in the different drivers where that could happen
because the arch specific drivers are written in such way it is not
possible to register a driver while it is unregistered, except maybe
in a very improbable case when "intel_idle" and "processor_idle" are
competing. One could unregister a driver, while the other one is
registering.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

parent 42f67f2a

drivers/cpuidle/driver.c

+1 −9

Original line number	Diff line number	Diff line
		@@ -85,17 +85,9 @@ EXPORT_SYMBOL_GPL(cpuidle_get_driver);
		*/
		void cpuidle_unregister_driver(struct cpuidle_driver *drv)
		{
		if (drv != cpuidle_curr_driver) {
		WARN(1, "invalid cpuidle_unregister_driver(%s)\n",
		drv->name);
		return;
		}

		spin_lock(&cpuidle_driver_lock);

		if (!WARN_ON(drv->refcnt > 0))
		if (drv == cpuidle_curr_driver && !WARN_ON(drv->refcnt > 0))
		cpuidle_curr_driver = NULL;

		spin_unlock(&cpuidle_driver_lock);
		}
		EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);