From 825a52482a616d74bd2f5eacc0f8946d025499a7 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Sat, 31 Jul 2021 10:34:46 +0200 Subject: 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: e8ad415b7a55 ("ALSA: core: Add managed card creation") Link: https://lore.kernel.org/r/20210731083446.26680-1-tiwai@suse.de Signed-off-by: Takashi Iwai --- sound/core/init.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'sound/core') diff --git a/sound/core/init.c b/sound/core/init.c index e985185ebc91..ac335f5906c6 100644 --- a/sound/core/init.c +++ b/sound/core/init.c @@ -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); } /** -- cgit