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 --- drivers/cpuidle/driver.c | 10 +--------- 1 files changed, 1 insertions(+), 9 deletions(-)
diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c index 39ba8e1..3e59075 100644 --- a/drivers/cpuidle/driver.c +++ b/drivers/cpuidle/driver.c @@ -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);