diff options
Diffstat (limited to 'sound/core/pcm_native.c')
| -rw-r--r-- | sound/core/pcm_native.c | 42 |
1 files changed, 27 insertions, 15 deletions
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index a8b27cdc2844..9106d8e2300e 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -74,6 +74,18 @@ static int snd_pcm_open(struct file *file, struct snd_pcm *pcm, int stream); static DEFINE_RWLOCK(snd_pcm_link_rwlock); static DECLARE_RWSEM(snd_pcm_link_rwsem); +/* Writer in rwsem may block readers even during its waiting in queue, + * and this may lead to a deadlock when the code path takes read sem + * twice (e.g. one in snd_pcm_action_nonatomic() and another in + * snd_pcm_stream_lock()). As a (suboptimal) workaround, let writer to + * spin until it gets the lock. + */ +static inline void down_write_nonblock(struct rw_semaphore *lock) +{ + while (!down_write_trylock(lock)) + cond_resched(); +} + /** * snd_pcm_stream_lock - Lock the PCM stream * @substream: PCM substream @@ -875,7 +887,7 @@ struct action_ops { * Note: the stream state might be changed also on failure * Note2: call with calling stream lock + link lock */ -static int snd_pcm_action_group(struct action_ops *ops, +static int snd_pcm_action_group(const struct action_ops *ops, struct snd_pcm_substream *substream, int state, int do_lock) { @@ -932,7 +944,7 @@ static int snd_pcm_action_group(struct action_ops *ops, /* * Note: call with stream lock */ -static int snd_pcm_action_single(struct action_ops *ops, +static int snd_pcm_action_single(const struct action_ops *ops, struct snd_pcm_substream *substream, int state) { @@ -952,7 +964,7 @@ static int snd_pcm_action_single(struct action_ops *ops, /* * Note: call with stream lock */ -static int snd_pcm_action(struct action_ops *ops, +static int snd_pcm_action(const struct action_ops *ops, struct snd_pcm_substream *substream, int state) { @@ -984,7 +996,7 @@ static int snd_pcm_action(struct action_ops *ops, /* * Note: don't use any locks before */ -static int snd_pcm_action_lock_irq(struct action_ops *ops, +static int snd_pcm_action_lock_irq(const struct action_ops *ops, struct snd_pcm_substream *substream, int state) { @@ -998,7 +1010,7 @@ static int snd_pcm_action_lock_irq(struct action_ops *ops, /* */ -static int snd_pcm_action_nonatomic(struct action_ops *ops, +static int snd_pcm_action_nonatomic(const struct action_ops *ops, struct snd_pcm_substream *substream, int state) { @@ -1056,7 +1068,7 @@ static void snd_pcm_post_start(struct snd_pcm_substream *substream, int state) snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MSTART); } -static struct action_ops snd_pcm_action_start = { +static const struct action_ops snd_pcm_action_start = { .pre_action = snd_pcm_pre_start, .do_action = snd_pcm_do_start, .undo_action = snd_pcm_undo_start, @@ -1107,7 +1119,7 @@ static void snd_pcm_post_stop(struct snd_pcm_substream *substream, int state) wake_up(&runtime->tsleep); } -static struct action_ops snd_pcm_action_stop = { +static const struct action_ops snd_pcm_action_stop = { .pre_action = snd_pcm_pre_stop, .do_action = snd_pcm_do_stop, .post_action = snd_pcm_post_stop @@ -1224,7 +1236,7 @@ static void snd_pcm_post_pause(struct snd_pcm_substream *substream, int push) } } -static struct action_ops snd_pcm_action_pause = { +static const struct action_ops snd_pcm_action_pause = { .pre_action = snd_pcm_pre_pause, .do_action = snd_pcm_do_pause, .undo_action = snd_pcm_undo_pause, @@ -1273,7 +1285,7 @@ static void snd_pcm_post_suspend(struct snd_pcm_substream *substream, int state) wake_up(&runtime->tsleep); } -static struct action_ops snd_pcm_action_suspend = { +static const struct action_ops snd_pcm_action_suspend = { .pre_action = snd_pcm_pre_suspend, .do_action = snd_pcm_do_suspend, .post_action = snd_pcm_post_suspend @@ -1375,7 +1387,7 @@ static void snd_pcm_post_resume(struct snd_pcm_substream *substream, int state) snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MRESUME); } -static struct action_ops snd_pcm_action_resume = { +static const struct action_ops snd_pcm_action_resume = { .pre_action = snd_pcm_pre_resume, .do_action = snd_pcm_do_resume, .undo_action = snd_pcm_undo_resume, @@ -1478,7 +1490,7 @@ static void snd_pcm_post_reset(struct snd_pcm_substream *substream, int state) snd_pcm_playback_silence(substream, ULONG_MAX); } -static struct action_ops snd_pcm_action_reset = { +static const struct action_ops snd_pcm_action_reset = { .pre_action = snd_pcm_pre_reset, .do_action = snd_pcm_do_reset, .post_action = snd_pcm_post_reset @@ -1522,7 +1534,7 @@ static void snd_pcm_post_prepare(struct snd_pcm_substream *substream, int state) snd_pcm_set_state(substream, SNDRV_PCM_STATE_PREPARED); } -static struct action_ops snd_pcm_action_prepare = { +static const struct action_ops snd_pcm_action_prepare = { .pre_action = snd_pcm_pre_prepare, .do_action = snd_pcm_do_prepare, .post_action = snd_pcm_post_prepare @@ -1618,7 +1630,7 @@ static void snd_pcm_post_drain_init(struct snd_pcm_substream *substream, int sta { } -static struct action_ops snd_pcm_action_drain_init = { +static const struct action_ops snd_pcm_action_drain_init = { .pre_action = snd_pcm_pre_drain_init, .do_action = snd_pcm_do_drain_init, .post_action = snd_pcm_post_drain_init @@ -1813,7 +1825,7 @@ static int snd_pcm_link(struct snd_pcm_substream *substream, int fd) res = -ENOMEM; goto _nolock; } - down_write(&snd_pcm_link_rwsem); + down_write_nonblock(&snd_pcm_link_rwsem); write_lock_irq(&snd_pcm_link_rwlock); if (substream->runtime->status->state == SNDRV_PCM_STATE_OPEN || substream->runtime->status->state != substream1->runtime->status->state || @@ -1860,7 +1872,7 @@ static int snd_pcm_unlink(struct snd_pcm_substream *substream) struct snd_pcm_substream *s; int res = 0; - down_write(&snd_pcm_link_rwsem); + down_write_nonblock(&snd_pcm_link_rwsem); write_lock_irq(&snd_pcm_link_rwlock); if (!snd_pcm_stream_linked(substream)) { res = -EALREADY; |
