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ALSA: core: Fix double calls of snd_card_free() via devres 

At the transition to the devres-managed card release, we've put the
check of double-free at trigger_card_release().  But this wasn't
enough, as the code path calls snd_card_free() again, and it would
lead to the doubly snd_card_free() calls.

Actually the v1 patch was correct to handle this, but I forgot that
corner case and moved the check to the more obvious place as I thought
it's clearer.  But, as usual, devils live in details.

This patch corrects the check of the double-free to the right place,
with a bit more comments.

Fixes: e8ad415b7a ("ALSA: core: Add managed card creation")
Link: https://lore.kernel.org/r/20210731083446.26680-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2021-07-31 10:34:46 +02:00
parent fac24b0f34
commit 825a52482a
1 changed files with 10 additions and 4 deletions
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14
sound/core/init.c
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@ -605,6 +605,15 @@ int snd_card_free(struct snd_card *card)
DECLARE_COMPLETION_ONSTACK(released);
int ret;
/* The call of snd_card_free() is allowed from various code paths;
* a manual call from the driver and the call via devres_free, and
* we need to avoid double-free. Moreover, the release via devres
* may call snd_card_free() twice due to its nature, we need to have
* the check here at the beginning.
*/
if (card->releasing)
return 0;
card->release_completion = &released;
ret = snd_card_free_when_closed(card);
if (ret)
@ -813,10 +822,7 @@ EXPORT_SYMBOL_GPL(snd_card_add_dev_attr);
static void trigger_card_free(void *data)
{
struct snd_card *card = data;
if (!card->releasing)
snd_card_free(data);
snd_card_free(data);
}
/**