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authorTakashi Iwai <tiwai@suse.de>2012-10-16 13:05:59 +0200
committerTakashi Iwai <tiwai@suse.de>2012-10-30 11:07:10 +0100
commita0830dbd4e42b38aefdf3fb61ba5019a1a99ea85 (patch)
tree4dc74b708a07b56d12ed72a34d0a2e0cb8c8b9d4 /sound/core/sound_oss.c
parent888ea7d5ac6815ba16b3b3a20f665a92c7af6724 (diff)
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>
Diffstat (limited to 'sound/core/sound_oss.c')
-rw-r--r--sound/core/sound_oss.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/sound/core/sound_oss.c b/sound/core/sound_oss.c
index e9528333e36d..e1d79ee35906 100644
--- a/sound/core/sound_oss.c
+++ b/sound/core/sound_oss.c
@@ -40,6 +40,9 @@
static struct snd_minor *snd_oss_minors[SNDRV_OSS_MINORS];
static DEFINE_MUTEX(sound_oss_mutex);
+/* NOTE: This function increments the refcount of the associated card like
+ * snd_lookup_minor_data(); the caller must call snd_card_unref() appropriately
+ */
void *snd_lookup_oss_minor_data(unsigned int minor, int type)
{
struct snd_minor *mreg;
@@ -49,9 +52,11 @@ void *snd_lookup_oss_minor_data(unsigned int minor, int type)
return NULL;
mutex_lock(&sound_oss_mutex);
mreg = snd_oss_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_oss_mutex);
return private_data;
@@ -123,6 +128,7 @@ int snd_register_oss_device(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_oss_mutex);
snd_oss_minors[minor] = preg;
minor_unit = SNDRV_MINOR_OSS_DEVICE(minor);