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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>
This commit is contained in:
Daniel Lezcano 2012-10-31 16:44:46 +00:00 committed by Rafael J. Wysocki
parent 42f67f2aca
commit 4168203271
1 changed files with 1 additions and 9 deletions
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10
drivers/cpuidle/driver.c
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@ -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);