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ALSA: pcm: Fix races among concurrent prepare and hw_params/hw_free calls

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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>
This commit is contained in:
Takashi Iwai 2022-03-22 18:07:19 +01:00
parent dca947d4d2
commit 3c3201f8c7
1 changed files with 18 additions and 14 deletions
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32
sound/core/pcm_native.c
View file

@ -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;
}