[PATCH 2/3] ALSA: core: Add scoped cleanup helper for card references

[Cássio Gabriel]

Several ALSA paths acquire temporary card references with snd_card_ref()
and release them manually with snd_card_unref(). control_led.c already
defines a local cleanup helper for this pattern, while other core paths
still open-code the release.

Move the helper to the common ALSA core header and use it in control-layer
card-reference paths. This makes the ownership rule explicit and avoids
future missing-unref mistakes when adding early exits.

No functional change is intended.

Signed-off-by: Cássio Gabriel <cassiogabrielcontato@xxxxxxxxx>
---
 include/sound/core.h     |  2 ++
 sound/core/control.c     |  6 +++---
 sound/core/control_led.c | 11 ++++-------
 3 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/include/sound/core.h b/include/sound/core.h
index 4bb76c21c956..8b2ca95d13f7 100644
--- a/include/sound/core.h
+++ b/include/sound/core.h
@@ -319,6 +319,8 @@ static inline void snd_card_unref(struct snd_card *card)
 	put_device(&card->card_dev);
 }
 
+DEFINE_FREE(snd_card_unref, struct snd_card *, if (_T) snd_card_unref(_T))
+
 #define snd_card_set_dev(card, devptr) ((card)->dev = (devptr))
 
 /* device.c */
diff --git a/sound/core/control.c b/sound/core/control.c
index 28fffbe92e66..7a8dc506221e 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -2291,7 +2291,6 @@ EXPORT_SYMBOL_GPL(snd_ctl_request_layer);
  */
 void snd_ctl_register_layer(struct snd_ctl_layer_ops *lops)
 {
-	struct snd_card *card;
 	int card_number;
 
 	scoped_guard(rwsem_write, &snd_ctl_layer_rwsem) {
@@ -2299,11 +2298,12 @@ void snd_ctl_register_layer(struct snd_ctl_layer_ops *lops)
 		snd_ctl_layer = lops;
 	}
 	for (card_number = 0; card_number < SNDRV_CARDS; card_number++) {
-		card = snd_card_ref(card_number);
+		struct snd_card *card __free(snd_card_unref) =
+			snd_card_ref(card_number);
+
 		if (card) {
 			scoped_guard(rwsem_read, &card->controls_rwsem)
 				lops->lregister(card);
-			snd_card_unref(card);
 		}
 	}
 }
diff --git a/sound/core/control_led.c b/sound/core/control_led.c
index d92b36ab5ec6..8cbacee57ce7 100644
--- a/sound/core/control_led.c
+++ b/sound/core/control_led.c
@@ -240,8 +240,6 @@ static void snd_ctl_led_notify(struct snd_card *card, unsigned int mask,
 	}
 }
 
-DEFINE_FREE(snd_card_unref, struct snd_card *, if (_T) snd_card_unref(_T))
-
 static int snd_ctl_led_set_id(int card_number, struct snd_ctl_elem_id *id,
 			      unsigned int group, bool set)
 {
@@ -758,18 +756,17 @@ static int __init snd_ctl_led_init(void)
 static void __exit snd_ctl_led_exit(void)
 {
 	struct snd_ctl_led *led;
-	struct snd_card *card;
 	unsigned int group, card_number;
 
 	snd_ctl_disconnect_layer(&snd_ctl_led_lops);
 	for (card_number = 0; card_number < SNDRV_CARDS; card_number++) {
 		if (!snd_ctl_led_card_valid[card_number])
 			continue;
-		card = snd_card_ref(card_number);
-		if (card) {
+		struct snd_card *card __free(snd_card_unref) =
+			snd_card_ref(card_number);
+
+		if (card)
 			snd_ctl_led_sysfs_remove(card);
-			snd_card_unref(card);
-		}
 	}
 	for (group = 0; group < MAX_LED; group++) {
 		led = &snd_ctl_leds[group];

-- 
2.54.0