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>

1 files changed, 7 insertions, 12 deletions

diff --git a/sound/core/control.c b/sound/core/control.c
index 9d91f77bc880..bc64b723415b 100644
--- 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)