cpuidle: Check if device is already registered

Make __cpuidle_register_device() check whether or not the device has
been registered already and return -EBUSY immediately if that's the
case.

[rjw: Changelog]
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 5b63185da59b..d75040ddd2b3 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -400,13 +400,16 @@ static int __cpuidle_register_device(struct cpuidle_device *dev)
  */
 int cpuidle_register_device(struct cpuidle_device *dev)
 {
-        int ret;
+        int ret = -EBUSY;
 
         if (!dev)
                 return -EINVAL;
 
         mutex_lock(&cpuidle_lock);
 
+        if (dev->registered)
+                goto out_unlock;
+
         ret = __cpuidle_device_init(dev);
         if (ret)
                 goto out_unlock;