[alsa-devel] [PATCH 3/5] ALSA: control: fix logic error about control count in a device

[Takashi Sakamoto]

It's assumed that the number of userspace controls is just 1 in several
parts, while this assumptions is not always true because the value of
'owner' member can be assigned to.

This commit fixes this issue.

Signed-off-by: Takashi Sakamoto <o-takashi at sakamocchi.jp>
---
 sound/core/control.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/sound/core/control.c b/sound/core/control.c
index 1edd6c5..bce4730 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -514,6 +514,7 @@ static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
 {
 	struct snd_card *card = file->card;
 	struct snd_kcontrol *kctl;
+	unsigned int count;
 	int i, ret;
 
 	down_write(&card->controls_rwsem);
@@ -531,10 +532,11 @@ static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
 			ret = -EBUSY;
 			goto error;
 		}
+	count = kctl->count;
 	ret = snd_ctl_remove(card, kctl);
 	if (ret < 0)
 		goto error;
-	card->user_ctl_count--;
+	card->user_ctl_count -= count;
 error:
 	up_write(&card->controls_rwsem);
 	return ret;
@@ -1202,10 +1204,15 @@ static int snd_ctl_elem_add(struct snd_ctl_file *file,
 			return err;
 	}
 
-	if (card->user_ctl_count >= MAX_USER_CONTROLS)
-		return -ENOMEM;
+	/*
+	 * The number of controls with the same feature, distinguished by index.
+	 */
+	kctl.count = info->owner;
+	if (kctl.count == 0)
+		kctl.count = 1;
+	if (card->user_ctl_count + kctl.count > MAX_USER_CONTROLS)
+		return -ENOSPC;
 
-	kctl.count = info->owner ? info->owner : 1;
 	if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED)
 		kctl.info = snd_ctl_elem_user_enum_info;
 	else
@@ -1259,7 +1266,7 @@ static int snd_ctl_elem_add(struct snd_ctl_file *file,
 		return err;
 
 	down_write(&card->controls_rwsem);
-	card->user_ctl_count++;
+	card->user_ctl_count += _kctl->count;
 	up_write(&card->controls_rwsem);
 
 	return 0;
-- 
2.1.0