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Commit 585fc83e authored by Chanwoo Choi's avatar Chanwoo Choi Committed by MyungJoo Ham
Browse files

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: default avatarChanwoo Choi <cw00.choi@samsung.com>
[Merge conflict resolved by MyungJoo]
Signed-off-by: default avatarMyungJoo Ham <myungjoo.ham@samsung.com>
parent 26d51853

drivers/devfreq/devfreq.c

+4 −10
Original line number Diff line number Diff line
@@ -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;

}