[PATCH] ALSA: core: Make sure to call snd_card_disconnect() at freeing

[PATCH] ALSA: core: Make sure to call snd_card_disconnect() at freeing

[Takashi Iwai]

When a card object gets freed via devres, it might be freed without
calling snd_card_disconnect(), and it might forget to release some
resources such as the procfs that gets deleted at the disconnect call.

Add an explicit call of snd_card_disconnect() at snd_card_do_free()
for assuring the preparation for cleanup.

Fixes: e8ad415b7a55 ("ALSA: core: Add managed card creation")
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---

This patch is required as a prerequisite for the recent cleanup series
to use auto-cleanup:
  http://lore.kernel.org/20261001110447.486782-1-tiwai@suse.de

 sound/core/init.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sound/core/init.c b/sound/core/init.c
index 0897b3a11617..764d3d1073e7 100644
--- a/sound/core/init.c
+++ b/sound/core/init.c
@@ -564,6 +564,10 @@ static int snd_card_do_free(struct snd_card *card)
 	bool managed = card->managed;
 
 	card->releasing = true;
+
+	/* for case without explicit disconnect call (e.g. via devres) */
+	snd_card_disconnect(card);
+
 #if IS_ENABLED(CONFIG_SND_MIXER_OSS)
 	if (snd_mixer_oss_notify_callback)
 		snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_FREE);
-- 
2.55.0

Re: [PATCH] ALSA: core: Make sure to call snd_card_disconnect() at freeing

[Takashi Iwai]

On Thu, 01 Oct 2026 15:18:09 +0200,
Takashi Iwai wrote:
> 
> When a card object gets freed via devres, it might be freed without
> calling snd_card_disconnect(), and it might forget to release some
> resources such as the procfs that gets deleted at the disconnect call.
> 
> Add an explicit call of snd_card_disconnect() at snd_card_do_free()
> for assuring the preparation for cleanup.
> 
> Fixes: e8ad415b7a55 ("ALSA: core: Add managed card creation")
> Signed-off-by: Takashi Iwai <tiwai@suse.de>
> ---
> 
> This patch is required as a prerequisite for the recent cleanup series
> to use auto-cleanup:
>   http://lore.kernel.org/20261001110447.486782-1-tiwai@suse.de

Scratch this (and the series above).

It turned out that this can be problematic in another subtle way.
Namely, when snd_card_disconnect() is called from the card_dev's
destructor, it can double-free the card_dev via device_del().
Skipping this call doesn't suffice as dpm_list may be still unbalanced
without the explicit call of device_del() beforehand...

A new fix and another series of cleanups will come up later.


Takashi