sound: snd_ctl_remove_unlocked_id: simplify user control counting

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>

diff --git a/sound/core/control.c b/sound/core/control.c
index 9d91f77..bc64b72 100644 (file)
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -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)