ALSA: use correct lock in snd_ctl_dev_disconnect()

commit d8009882 upstream

The lock used in snd_ctl_dev_disconnect() should be card->ctl_files_rwlock
for protection of card->ctl_files entries, instead of card->controls_rwsem.
Reported-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Cc: Chris Wedgwood <cw@f00f.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

sound/core/control.c

@@ -1426,12 +1426,12 @@ static int snd_ctl_dev_disconnect(struct snd_device *device)
 	cardnum = card->number;
 	snd_assert(cardnum >= 0 && cardnum < SNDRV_CARDS, return -ENXIO);
 
-	down_read(&card->controls_rwsem);
+	read_lock(&card->ctl_files_rwlock);
 	list_for_each_entry(ctl, &card->ctl_files, list) {
 		wake_up(&ctl->change_sleep);
 		kill_fasync(&ctl->fasync, SIGIO, POLL_ERR);
 	}
-	up_read(&card->controls_rwsem);
+	read_unlock(&card->ctl_files_rwlock);
 
 	if ((err = snd_unregister_device(SNDRV_DEVICE_TYPE_CONTROL,
 					 card, -1)) < 0)