ALSA: Add a reference counter to card instance
For more strict protection for wild disconnections, a refcount is
introduced to the card instance, and let it up/down when an object is
referred via snd_lookup_*() in the open ops.
The free-after-last-close check is also changed to check this refcount
instead of the empty list, too.
Reported-by: Matthieu CASTET <matthieu.castet@parrot.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/control.c b/sound/core/control.c
index 7e86a5b9..9768a39 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -86,6 +86,7 @@
write_lock_irqsave(&card->ctl_files_rwlock, flags);
list_add_tail(&ctl->list, &card->ctl_files);
write_unlock_irqrestore(&card->ctl_files_rwlock, flags);
+ snd_card_unref(card);
return 0;
__error:
@@ -93,6 +94,8 @@
__error2:
snd_card_file_remove(card, file);
__error1:
+ if (card)
+ snd_card_unref(card);
return err;
}