[PATCH v3 4/7] ALSA: info: Fix memory leak at card removal

[Takashi Iwai <tiwai@suse.de>]

The fix for potential deadlock at disconnection by the commit
c7a606519533 ("ALSA: info: Fix potential deadlock at disconnection")
clears card->proc_root pointer at snd_info_card_disconnect(), in order
just to be sure.  But this leads to a memory leak of card->proc_root
content that should have been released at a later call of
snd_info_card_free().

For addressing the memory leak, simply drop the card->proc_root
clearance at snd_info_card_disconnect().

Since card->proc_root might be still looked at in
snd_info_card_id_change() that may be running concurrently during the
connection procedure, add a sanity check there, too.

Fixes: c7a606519533 ("ALSA: info: Fix potential deadlock at disconnection")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20261006174002.703431-1-tiwai%40suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/core/info.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sound/core/info.c b/sound/core/info.c
index 3b8ccda04e1a..c4d57d0809ad 100644
--- a/sound/core/info.c
+++ b/sound/core/info.c
@@ -528,6 +528,8 @@ int snd_info_card_register(struct snd_card *card)
 void snd_info_card_id_change(struct snd_card *card)
 {
 	guard(mutex)(&info_mutex);
+	if (card->shutdown)
+		return;
 	if (card->proc_root_link) {
 		proc_remove(card->proc_root_link);
 		card->proc_root_link = NULL;
@@ -555,7 +557,6 @@ void snd_info_card_disconnect(struct snd_card *card)
 	if (card->proc_root)
 		snd_info_clear_entries(card->proc_root);
 	card->proc_root_link = NULL;
-	card->proc_root = NULL;
 }
 
 /*
-- 
2.55.0