PM / devfreq: Fix devfreq_remove_device() to improve the sequence of resource free

This patch modify devfreq_remove_device() to improve the sequence of resource
free. If executing existing devfreq_remove_device(), this function always
executes _remove_devfreq() twice. In result, second _remove_devfreq() always
return error value. So, This patch resolves complicated function sequence
as following:

[Flow sequence before modification]
devfreq_remove_device()
   _remove_devfreq(devfreq, false)
      kfree(devfreq);  /* Free devfreq */
      if (!skip ...) { /* skip is false */
         device_unregister(&devfreq->dev)
         put_device(&devfreq->dev);
            ...
            dev->release()
               devfreq_dev_release()
                  _remove_devfreq(devfreq, true) <- Recall to free devfreq
                  /*
		   * Always return error without freeing resource because
		   * already _remove_devfreq() frees the memory of devfreq.
		   */
   }

[Flow sequence after modification]
devfreq_remove_device
   device_unregister(&devfreq->dev)
   put_device(&devfreq->dev);
      ..
      dev->release()
         devfreq_dev_release()
            _remove_devfreq()
               kfree(devfreq); /* Free devfreq */

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
[Merge conflict resolved by MyungJoo]
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>

1 files changed, 4 insertions, 10 deletions

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 2042ec3656ba..af4af7708574 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -394,7 +394,7 @@ static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
  * @devfreq:    the devfreq struct
  * @skip:       skip calling device_unregister().
  */
-static void _remove_devfreq(struct devfreq *devfreq, bool skip)
+static void _remove_devfreq(struct devfreq *devfreq)
 {
         mutex_lock(&devfreq_list_lock);
         if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
@@ -412,11 +412,6 @@ static void _remove_devfreq(struct devfreq *devfreq, bool skip)
         if (devfreq->profile->exit)
                 devfreq->profile->exit(devfreq->dev.parent);
 
-        if (!skip && get_device(&devfreq->dev)) {
-                device_unregister(&devfreq->dev);
-                put_device(&devfreq->dev);
-        }
-
         mutex_destroy(&devfreq->lock);
         kfree(devfreq);
 }
@@ -426,14 +421,12 @@ static void _remove_devfreq(struct devfreq *devfreq, bool skip)
  * @dev:        the devfreq device
  *
  * This calls _remove_devfreq() if _remove_devfreq() is not called.
- * Note that devfreq_dev_release() could be called by _remove_devfreq() as
- * well as by others unregistering the device.
  */
 static void devfreq_dev_release(struct device *dev)
 {
         struct devfreq *devfreq = to_devfreq(dev);
 
-        _remove_devfreq(devfreq, true);
+        _remove_devfreq(devfreq);
 }
 
 /**
@@ -544,7 +537,8 @@ int devfreq_remove_device(struct devfreq *devfreq)
         if (!devfreq)
                 return -EINVAL;
 
-        _remove_devfreq(devfreq, false);
+        device_unregister(&devfreq->dev);
+        put_device(&devfreq->dev);
 
         return 0;
 }