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/include/sound/core.h b/include/sound/core.h
index bc05668..93896ad 100644
--- a/include/sound/core.h
+++ b/include/sound/core.h
@@ -132,6 +132,7 @@
int shutdown; /* this card is going down */
int free_on_last_close; /* free in context of file_release */
wait_queue_head_t shutdown_sleep;
+ atomic_t refcount; /* refcount for disconnection */
struct device *dev; /* device assigned to this card */
struct device *card_dev; /* cardX object for sysfs */
@@ -189,6 +190,7 @@
const struct file_operations *f_ops; /* file operations */
void *private_data; /* private data for f_ops->open */
struct device *dev; /* device for sysfs */
+ struct snd_card *card_ptr; /* assigned card instance */
};
/* return a device pointer linked to each sound device as a parent */
@@ -295,6 +297,7 @@
int snd_component_add(struct snd_card *card, const char *component);
int snd_card_file_add(struct snd_card *card, struct file *file);
int snd_card_file_remove(struct snd_card *card, struct file *file);
+void snd_card_unref(struct snd_card *card);
#define snd_card_set_dev(card, devptr) ((card)->dev = (devptr))