[PATCH 5.15.y] ALSA: control: Avoid WARN() for symlink errors

[Robert Garcia]

From: Takashi Iwai <tiwai@xxxxxxx>

[ Upstream commit b2e538a9827dd04ab5273bf4be8eb2edb84357b0 ]

Using WARN() for showing the error of symlink creations don't give
more information than telling that something goes wrong, since the
usual code path is a lregister callback from each control element
creation.  More badly, the use of WARN() rather confuses fuzzer as if
it were serious issues.

This patch downgrades the warning messages to use the normal dev_err()
instead of WARN().  For making it clearer, add the function name to
the prefix, too.

Fixes: a135dfb5de15 ("ALSA: led control - add sysfs kcontrol LED marking layer")
Reported-by: syzbot+4e7919b09c67ffd198ae@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/675664c7.050a0220.a30f1.018c.GAE@xxxxxxxxxx
Link: https://patch.msgid.link/20241209095614.4273-1-tiwai@xxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
[ Use card->ctl_dev.kobj to keep struct consistent. ]
Signed-off-by: Robert Garcia <rob_garcia@xxxxxxx>
---
 sound/core/control_led.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/sound/core/control_led.c b/sound/core/control_led.c
index 3eb1c5af82ad..df836ff550f8 100644
--- a/sound/core/control_led.c
+++ b/sound/core/control_led.c
@@ -693,10 +693,16 @@ static void snd_ctl_led_sysfs_add(struct snd_card *card)
 			goto cerr;
 		led->cards[card->number] = led_card;
 		snprintf(link_name, sizeof(link_name), "led-%s", led->name);
-		WARN(sysfs_create_link(&card->ctl_dev.kobj, &led_card->dev.kobj, link_name),
-			"can't create symlink to controlC%i device\n", card->number);
-		WARN(sysfs_create_link(&led_card->dev.kobj, &card->card_dev.kobj, "card"),
-			"can't create symlink to card%i\n", card->number);
+		if (sysfs_create_link(&card->ctl_dev.kobj, &led_card->dev.kobj,
+				      link_name))
+			dev_err(card->dev,
+				"%s: can't create symlink to controlC%i device\n",
+				 __func__, card->number);
+		if (sysfs_create_link(&led_card->dev.kobj, &card->card_dev.kobj,
+				      "card"))
+			dev_err(card->dev,
+				"%s: can't create symlink to card%i\n",
+				__func__, card->number);
 
 		continue;
 cerr:
-- 
2.34.1