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sound: snd_ctl_remove_unlocked_id: simplify user control counting

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Move the decrementing of the user controls counter from
snd_ctl_elem_remove to snd_ctl_remove_unlocked_id; this saves the
separate locking of the controls semaphore, and therefore removes
a harmless race.

Since the purpose of the function is to operate on user controls (the
control being unlocked is just a prerequisite), rename it to
snd_ctl_remove_user_ctl.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Clemens Ladisch 2009-08-17 12:27:22 +02:00 committed by Takashi Iwai
parent 317b80817f
commit f217ac59b6
1 changed files with 7 additions and 12 deletions
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19
sound/core/control.c
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@ -414,7 +414,7 @@ int snd_ctl_remove_id(struct snd_card *card, struct snd_ctl_elem_id *id)
EXPORT_SYMBOL(snd_ctl_remove_id);
/**
* snd_ctl_remove_unlocked_id - remove the unlocked control of the given id and release it
* snd_ctl_remove_user_ctl - remove and release the unlocked user control
* @file: active control handle
* @id: the control id to remove
*
@ -423,8 +423,8 @@ EXPORT_SYMBOL(snd_ctl_remove_id);
*
* Returns 0 if successful, or a negative error code on failure.
*/
static int snd_ctl_remove_unlocked_id(struct snd_ctl_file * file,
struct snd_ctl_elem_id *id)
static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
struct snd_ctl_elem_id *id)
{
struct snd_card *card = file->card;
struct snd_kcontrol *kctl;
@ -442,6 +442,9 @@ static int snd_ctl_remove_unlocked_id(struct snd_ctl_file * file,
goto error;
}
ret = snd_ctl_remove(card, kctl);
if (ret < 0)
goto error;
card->user_ctl_count--;
error:
up_write(&card->controls_rwsem);
return ret;
@ -1053,18 +1056,10 @@ static int snd_ctl_elem_remove(struct snd_ctl_file *file,
struct snd_ctl_elem_id __user *_id)
{
struct snd_ctl_elem_id id;
int err;
if (copy_from_user(&id, _id, sizeof(id)))
return -EFAULT;
err = snd_ctl_remove_unlocked_id(file, &id);
if (! err) {
struct snd_card *card = file->card;
down_write(&card->controls_rwsem);
card->user_ctl_count--;
up_write(&card->controls_rwsem);
}
return err;
return snd_ctl_remove_user_ctl(file, &id);
}
static int snd_ctl_subscribe_events(struct snd_ctl_file *file, int __user *ptr)