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authorTakashi Iwai <tiwai@suse.de>2022-03-22 20:07:19 +0300
committerTakashi Iwai <tiwai@suse.de>2022-03-22 22:56:42 +0300
commit3c3201f8c7bb77eb53b08a3ca8d9a4ddc500b4c0 (patch)
treecdc35dbfdb8c8f75bf2d2ba62912327d616f570d /sound/core
parentdca947d4d26dbf925a64a6cfb2ddbc035e831a3d (diff)
downloadlinux-3c3201f8c7bb77eb53b08a3ca8d9a4ddc500b4c0.tar.xz
ALSA: pcm: Fix races among concurrent prepare and hw_params/hw_free calls
Like the previous fixes to hw_params and hw_free ioctl races, we need to paper over the concurrent prepare ioctl calls against hw_params and hw_free, too. This patch implements the locking with the existing runtime->buffer_mutex for prepare ioctls. Unlike the previous case for snd_pcm_hw_hw_params() and snd_pcm_hw_free(), snd_pcm_prepare() is performed to the linked streams, hence the lock can't be applied simply on the top. For tracking the lock in each linked substream, we modify snd_pcm_action_group() slightly and apply the buffer_mutex for the case stream_lock=false (formerly there was no lock applied) there. Cc: <stable@vger.kernel.org> Reviewed-by: Jaroslav Kysela <perex@perex.cz> Link: https://lore.kernel.org/r/20220322170720.3529-4-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/core')
-rw-r--r--sound/core/pcm_native.c32
1 files changed, 18 insertions, 14 deletions
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 266895374b83..0e4fbf5fd87b 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1190,15 +1190,17 @@ struct action_ops {
static int snd_pcm_action_group(const struct action_ops *ops,
struct snd_pcm_substream *substream,
snd_pcm_state_t state,
- bool do_lock)
+ bool stream_lock)
{
struct snd_pcm_substream *s = NULL;
struct snd_pcm_substream *s1;
int res = 0, depth = 1;
snd_pcm_group_for_each_entry(s, substream) {
- if (do_lock && s != substream) {
- if (s->pcm->nonatomic)
+ if (s != substream) {
+ if (!stream_lock)
+ mutex_lock_nested(&s->runtime->buffer_mutex, depth);
+ else if (s->pcm->nonatomic)
mutex_lock_nested(&s->self_group.mutex, depth);
else
spin_lock_nested(&s->self_group.lock, depth);
@@ -1226,18 +1228,18 @@ static int snd_pcm_action_group(const struct action_ops *ops,
ops->post_action(s, state);
}
_unlock:
- if (do_lock) {
- /* unlock streams */
- snd_pcm_group_for_each_entry(s1, substream) {
- if (s1 != substream) {
- if (s1->pcm->nonatomic)
- mutex_unlock(&s1->self_group.mutex);
- else
- spin_unlock(&s1->self_group.lock);
- }
- if (s1 == s) /* end */
- break;
+ /* unlock streams */
+ snd_pcm_group_for_each_entry(s1, substream) {
+ if (s1 != substream) {
+ if (!stream_lock)
+ mutex_unlock(&s1->runtime->buffer_mutex);
+ else if (s1->pcm->nonatomic)
+ mutex_unlock(&s1->self_group.mutex);
+ else
+ spin_unlock(&s1->self_group.lock);
}
+ if (s1 == s) /* end */
+ break;
}
return res;
}
@@ -1367,10 +1369,12 @@ static int snd_pcm_action_nonatomic(const struct action_ops *ops,
/* Guarantee the group members won't change during non-atomic action */
down_read(&snd_pcm_link_rwsem);
+ mutex_lock(&substream->runtime->buffer_mutex);
if (snd_pcm_stream_linked(substream))
res = snd_pcm_action_group(ops, substream, state, false);
else
res = snd_pcm_action_single(ops, substream, state);
+ mutex_unlock(&substream->runtime->buffer_mutex);
up_read(&snd_pcm_link_rwsem);
return res;
}