linux-kernel - [PATCH 6.1] ALSA: control: Avoid WARN() for symlink errors

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Message-ID: <20250321182701.1729403-1-sdl@nppct.ru>
Date: Fri, 21 Mar 2025 18:27:00 +0000
From: Alexey Nepomnyashih <sdl@...ct.ru>
To: Jaroslav Kysela <perex@...ex.cz>
Cc: Alexey Nepomnyashih <sdl@...ct.ru>,
	Takashi Iwai <tiwai@...e.com>,
	alsa-devel@...a-project.org,
	linux-kernel@...r.kernel.org,
	lvc-project@...uxtesting.org,
	syzbot+4e7919b09c67ffd198ae@...kaller.appspotmail.com,
	Takashi Iwai <tiwai@...e.de>
Subject: [PATCH 6.1] ALSA: control: Avoid WARN() for symlink errors

From: Takashi Iwai <tiwai@...e.de>

commit b2e538a9827dd04ab5273bf4be8eb2edb84357b0 upstream.

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@...kaller.appspotmail.com
Closes: https://lore.kernel.org/675664c7.050a0220.a30f1.018c.GAE@google.com
Link: https://patch.msgid.link/20241209095614.4273-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@...e.de>
[ Alexey Nepomnyashih: changed &card->ctl_dev->kobj
 to &card->ctl_dev.kobj. ]
Signed-off-by: Alexey Nepomnyashih <sdl@...ct.ru>
---
 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 3cadd40100f3..6d81a6a59f29 100644
--- a/sound/core/control_led.c
+++ b/sound/core/control_led.c
@@ -688,10 +688,16 @@ 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:
-- 
2.43.0