diff options
| author | Takashi Iwai <tiwai@suse.de> | 2012-10-16 13:05:59 +0200 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2012-11-16 16:46:50 +0000 |
| commit | 3b4a36722e5e518e4bdd3a215d8a1c5adc18e911 (patch) | |
| tree | 3db0ebb96a886ce6ff3c91e60510a03b561a20bc /sound/core/sound.c | |
| parent | f6415ce55f2430e38f674d8421511e489b2c71b0 (diff) | |
ALSA: Add a reference counter to card instance
commit a0830dbd4e42b38aefdf3fb61ba5019a1a99ea85 upstream.
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>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'sound/core/sound.c')
| -rw-r--r-- | sound/core/sound.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/sound/core/sound.c b/sound/core/sound.c index 828af353ea9..f1889768774 100644 --- a/sound/core/sound.c +++ b/sound/core/sound.c @@ -99,6 +99,10 @@ static void snd_request_other(int minor) * * Checks that a minor device with the specified type is registered, and returns * its user data pointer. + * + * This function increments the reference counter of the card instance + * if an associated instance with the given minor number and type is found. + * The caller must call snd_card_unref() appropriately later. */ void *snd_lookup_minor_data(unsigned int minor, int type) { @@ -109,9 +113,11 @@ void *snd_lookup_minor_data(unsigned int minor, int type) return NULL; mutex_lock(&sound_mutex); mreg = snd_minors[minor]; - if (mreg && mreg->type == type) + if (mreg && mreg->type == type) { private_data = mreg->private_data; - else + if (mreg->card_ptr) + atomic_inc(&mreg->card_ptr->refcount); + } else private_data = NULL; mutex_unlock(&sound_mutex); return private_data; @@ -275,6 +281,7 @@ int snd_register_device_for_dev(int type, struct snd_card *card, int dev, preg->device = dev; preg->f_ops = f_ops; preg->private_data = private_data; + preg->card_ptr = card; mutex_lock(&sound_mutex); #ifdef CONFIG_SND_DYNAMIC_MINORS minor = snd_find_free_minor(type); |