Commit 205d6bcf authored by Takashi Iwai's avatar Takashi Iwai
Browse files

Merge branch 'topic/pcm-lock-refactor' into for-next 



Pull PCM lock refactoring.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parents 3a554371 ef2056b8

include/sound/pcm.h

+2 −1
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#include <linux/mm.h>

#include <linux/bitops.h>

#include <linux/pm_qos.h>

#include <linux/refcount.h>



#define snd_pcm_substream_chip(substream) ((substream)->private_data)

#define snd_pcm_chip(pcm) ((pcm)->private_data)
@@ -439,7 +440,7 @@ struct snd_pcm_group { /* keep linked substreams */ 
	spinlock_t lock;

	struct mutex mutex;

	struct list_head substreams;

	int count;

	refcount_t refs;

};



struct pid;

sound/core/pcm.c

+1 −3
Original line number Diff line number Diff line
@@ -733,9 +733,7 @@ int snd_pcm_new_stream(struct snd_pcm *pcm, int stream, int substream_count) 
			}

		}

		substream->group = &substream->self_group;

		spin_lock_init(&substream->self_group.lock);

		mutex_init(&substream->self_group.mutex);

		INIT_LIST_HEAD(&substream->self_group.substreams);

		snd_pcm_group_init(&substream->self_group);

		list_add_tail(&substream->link_list, &substream->self_group.substreams);

		atomic_set(&substream->mmap_count, 0);

		prev = substream;

sound/core/pcm_local.h

+1 −0
Original line number Diff line number Diff line
@@ -66,5 +66,6 @@ static inline void snd_pcm_timer_done(struct snd_pcm_substream *substream) {} 
#endif



void __snd_pcm_xrun(struct snd_pcm_substream *substream);

void snd_pcm_group_init(struct snd_pcm_group *group);



#endif	/* __SOUND_CORE_PCM_LOCAL_H */

sound/core/pcm_native.c

+167 −123
Original line number Diff line number Diff line
@@ -85,71 +85,30 @@ 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

 * sleep until all the readers are completed without blocking by writer.

 */

static inline void down_write_nonfifo(struct rw_semaphore *lock)

void snd_pcm_group_init(struct snd_pcm_group *group)

{

	while (!down_write_trylock(lock))

		msleep(1);

	spin_lock_init(&group->lock);

	mutex_init(&group->mutex);

	INIT_LIST_HEAD(&group->substreams);

	refcount_set(&group->refs, 0);

}



#define PCM_LOCK_DEFAULT	0

#define PCM_LOCK_IRQ	1

#define PCM_LOCK_IRQSAVE	2



static unsigned long __snd_pcm_stream_lock_mode(struct snd_pcm_substream *substream,

						unsigned int mode)

{

	unsigned long flags = 0;

	if (substream->pcm->nonatomic) {

		down_read_nested(&snd_pcm_link_rwsem, SINGLE_DEPTH_NESTING);

		mutex_lock(&substream->self_group.mutex);

	} else {

		switch (mode) {

		case PCM_LOCK_DEFAULT:

			read_lock(&snd_pcm_link_rwlock);

			break;

		case PCM_LOCK_IRQ:

			read_lock_irq(&snd_pcm_link_rwlock);

			break;

		case PCM_LOCK_IRQSAVE:

			read_lock_irqsave(&snd_pcm_link_rwlock, flags);

			break;

		}

		spin_lock(&substream->self_group.lock);

/* define group lock helpers */

#define DEFINE_PCM_GROUP_LOCK(action, mutex_action) \

static void snd_pcm_group_ ## action(struct snd_pcm_group *group, bool nonatomic) \

{ \

	if (nonatomic) \

		mutex_ ## mutex_action(&group->mutex); \

	else \

		spin_ ## action(&group->lock); \

}

	return flags;

}



static void __snd_pcm_stream_unlock_mode(struct snd_pcm_substream *substream,

					 unsigned int mode, unsigned long flags)

{

	if (substream->pcm->nonatomic) {

		mutex_unlock(&substream->self_group.mutex);

		up_read(&snd_pcm_link_rwsem);

	} else {

		spin_unlock(&substream->self_group.lock);



		switch (mode) {

		case PCM_LOCK_DEFAULT:

			read_unlock(&snd_pcm_link_rwlock);

			break;

		case PCM_LOCK_IRQ:

			read_unlock_irq(&snd_pcm_link_rwlock);

			break;

		case PCM_LOCK_IRQSAVE:

			read_unlock_irqrestore(&snd_pcm_link_rwlock, flags);

			break;

		}

	}

}

DEFINE_PCM_GROUP_LOCK(lock, lock);

DEFINE_PCM_GROUP_LOCK(unlock, unlock);

DEFINE_PCM_GROUP_LOCK(lock_irq, lock);

DEFINE_PCM_GROUP_LOCK(unlock_irq, unlock);



/**

 * snd_pcm_stream_lock - Lock the PCM stream
@@ -161,7 +120,7 @@ static void __snd_pcm_stream_unlock_mode(struct snd_pcm_substream *substream, 
 */

void snd_pcm_stream_lock(struct snd_pcm_substream *substream)

{

	__snd_pcm_stream_lock_mode(substream, PCM_LOCK_DEFAULT);

	snd_pcm_group_lock(&substream->self_group, substream->pcm->nonatomic);

}

EXPORT_SYMBOL_GPL(snd_pcm_stream_lock);
@@ -173,7 +132,7 @@ EXPORT_SYMBOL_GPL(snd_pcm_stream_lock); 
 */

void snd_pcm_stream_unlock(struct snd_pcm_substream *substream)

{

	__snd_pcm_stream_unlock_mode(substream, PCM_LOCK_DEFAULT, 0);

	snd_pcm_group_unlock(&substream->self_group, substream->pcm->nonatomic);

}

EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock);
@@ -187,7 +146,8 @@ EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock); 
 */

void snd_pcm_stream_lock_irq(struct snd_pcm_substream *substream)

{

	__snd_pcm_stream_lock_mode(substream, PCM_LOCK_IRQ);

	snd_pcm_group_lock_irq(&substream->self_group,

			       substream->pcm->nonatomic);

}

EXPORT_SYMBOL_GPL(snd_pcm_stream_lock_irq);
@@ -199,13 +159,19 @@ EXPORT_SYMBOL_GPL(snd_pcm_stream_lock_irq); 
 */

void snd_pcm_stream_unlock_irq(struct snd_pcm_substream *substream)

{

	__snd_pcm_stream_unlock_mode(substream, PCM_LOCK_IRQ, 0);

	snd_pcm_group_unlock_irq(&substream->self_group,

				 substream->pcm->nonatomic);

}

EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock_irq);



unsigned long _snd_pcm_stream_lock_irqsave(struct snd_pcm_substream *substream)

{

	return __snd_pcm_stream_lock_mode(substream, PCM_LOCK_IRQSAVE);

	unsigned long flags = 0;

	if (substream->pcm->nonatomic)

		mutex_lock(&substream->self_group.mutex);

	else

		spin_lock_irqsave(&substream->self_group.lock, flags);

	return flags;

}

EXPORT_SYMBOL_GPL(_snd_pcm_stream_lock_irqsave);
@@ -219,7 +185,10 @@ EXPORT_SYMBOL_GPL(_snd_pcm_stream_lock_irqsave); 
void snd_pcm_stream_unlock_irqrestore(struct snd_pcm_substream *substream,

				      unsigned long flags)

{

	__snd_pcm_stream_unlock_mode(substream, PCM_LOCK_IRQSAVE, flags);

	if (substream->pcm->nonatomic)

		mutex_unlock(&substream->self_group.mutex);

	else

		spin_unlock_irqrestore(&substream->self_group.lock, flags);

}

EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock_irqrestore);
@@ -1124,6 +1093,68 @@ static int snd_pcm_action_single(const struct action_ops *ops, 
	return res;

}



static void snd_pcm_group_assign(struct snd_pcm_substream *substream,

				 struct snd_pcm_group *new_group)

{

	substream->group = new_group;

	list_move(&substream->link_list, &new_group->substreams);

}



/*

 * Unref and unlock the group, but keep the stream lock;

 * when the group becomes empty and no longer referred, destroy itself

 */

static void snd_pcm_group_unref(struct snd_pcm_group *group,

				struct snd_pcm_substream *substream)

{

	bool do_free;



	if (!group)

		return;

	do_free = refcount_dec_and_test(&group->refs) &&

		list_empty(&group->substreams);

	snd_pcm_group_unlock(group, substream->pcm->nonatomic);

	if (do_free)

		kfree(group);

}



/*

 * Lock the group inside a stream lock and reference it;

 * return the locked group object, or NULL if not linked

 */

static struct snd_pcm_group *

snd_pcm_stream_group_ref(struct snd_pcm_substream *substream)

{

	bool nonatomic = substream->pcm->nonatomic;

	struct snd_pcm_group *group;

	bool trylock;



	for (;;) {

		if (!snd_pcm_stream_linked(substream))

			return NULL;

		group = substream->group;

		/* block freeing the group object */

		refcount_inc(&group->refs);



		trylock = nonatomic ? mutex_trylock(&group->mutex) :

			spin_trylock(&group->lock);

		if (trylock)

			break; /* OK */



		/* re-lock for avoiding ABBA deadlock */

		snd_pcm_stream_unlock(substream);

		snd_pcm_group_lock(group, nonatomic);

		snd_pcm_stream_lock(substream);



		/* check the group again; the above opens a small race window */

		if (substream->group == group)

			break; /* OK */

		/* group changed, try again */

		snd_pcm_group_unref(group, substream);

	}

	return group;

}



/*

 *  Note: call with stream lock

 */
@@ -1131,28 +1162,15 @@ static int snd_pcm_action(const struct action_ops *ops, 
			  struct snd_pcm_substream *substream,

			  int state)

{

	struct snd_pcm_group *group;

	int res;



	if (!snd_pcm_stream_linked(substream))

		return snd_pcm_action_single(ops, substream, state);



	if (substream->pcm->nonatomic) {

		if (!mutex_trylock(&substream->group->mutex)) {

			mutex_unlock(&substream->self_group.mutex);

			mutex_lock(&substream->group->mutex);

			mutex_lock(&substream->self_group.mutex);

		}

	group = snd_pcm_stream_group_ref(substream);

	if (group)

		res = snd_pcm_action_group(ops, substream, state, 1);

		mutex_unlock(&substream->group->mutex);

	} else {

		if (!spin_trylock(&substream->group->lock)) {

			spin_unlock(&substream->self_group.lock);

			spin_lock(&substream->group->lock);

			spin_lock(&substream->self_group.lock);

		}

		res = snd_pcm_action_group(ops, substream, state, 1);

		spin_unlock(&substream->group->lock);

	}

	else

		res = snd_pcm_action_single(ops, substream, state);

	snd_pcm_group_unref(group, substream);

	return res;

}
@@ -1179,6 +1197,7 @@ static int snd_pcm_action_nonatomic(const struct action_ops *ops, 
{

	int res;



	/* Guarantee the group members won't change during non-atomic action */

	down_read(&snd_pcm_link_rwsem);

	if (snd_pcm_stream_linked(substream))

		res = snd_pcm_action_group(ops, substream, state, 0);
@@ -1802,6 +1821,7 @@ static int snd_pcm_drain(struct snd_pcm_substream *substream, 
	struct snd_card *card;

	struct snd_pcm_runtime *runtime;

	struct snd_pcm_substream *s;

	struct snd_pcm_group *group;

	wait_queue_entry_t wait;

	int result = 0;

	int nonblock = 0;
@@ -1818,7 +1838,6 @@ static int snd_pcm_drain(struct snd_pcm_substream *substream, 
	} else if (substream->f_flags & O_NONBLOCK)

		nonblock = 1;



	down_read(&snd_pcm_link_rwsem);

	snd_pcm_stream_lock_irq(substream);

	/* resume pause */

	if (runtime->status->state == SNDRV_PCM_STATE_PAUSED)
@@ -1843,6 +1862,7 @@ static int snd_pcm_drain(struct snd_pcm_substream *substream, 
		}

		/* find a substream to drain */

		to_check = NULL;

		group = snd_pcm_stream_group_ref(substream);

		snd_pcm_group_for_each_entry(s, substream) {

			if (s->stream != SNDRV_PCM_STREAM_PLAYBACK)

				continue;
@@ -1852,12 +1872,12 @@ static int snd_pcm_drain(struct snd_pcm_substream *substream, 
				break;

			}

		}

		snd_pcm_group_unref(group, substream);

		if (!to_check)

			break; /* all drained */

		init_waitqueue_entry(&wait, current);

		add_wait_queue(&to_check->sleep, &wait);

		snd_pcm_stream_unlock_irq(substream);

		up_read(&snd_pcm_link_rwsem);

		if (runtime->no_period_wakeup)

			tout = MAX_SCHEDULE_TIMEOUT;

		else {
@@ -1869,9 +1889,17 @@ static int snd_pcm_drain(struct snd_pcm_substream *substream, 
			tout = msecs_to_jiffies(tout * 1000);

		}

		tout = schedule_timeout_interruptible(tout);

		down_read(&snd_pcm_link_rwsem);



		snd_pcm_stream_lock_irq(substream);

		group = snd_pcm_stream_group_ref(substream);

		snd_pcm_group_for_each_entry(s, substream) {

			if (s->runtime == to_check) {

				remove_wait_queue(&to_check->sleep, &wait);

				break;

			}

		}

		snd_pcm_group_unref(group, substream);



		if (card->shutdown) {

			result = -ENODEV;

			break;
@@ -1891,7 +1919,6 @@ static int snd_pcm_drain(struct snd_pcm_substream *substream, 


 unlock:

	snd_pcm_stream_unlock_irq(substream);

	up_read(&snd_pcm_link_rwsem);



	return result;

}
@@ -1930,13 +1957,19 @@ static int snd_pcm_drop(struct snd_pcm_substream *substream) 
static bool is_pcm_file(struct file *file)

{

	struct inode *inode = file_inode(file);

	struct snd_pcm *pcm;

	unsigned int minor;



	if (!S_ISCHR(inode->i_mode) || imajor(inode) != snd_major)

		return false;

	minor = iminor(inode);

	return snd_lookup_minor_data(minor, SNDRV_DEVICE_TYPE_PCM_PLAYBACK) ||

		snd_lookup_minor_data(minor, SNDRV_DEVICE_TYPE_PCM_CAPTURE);

	pcm = snd_lookup_minor_data(minor, SNDRV_DEVICE_TYPE_PCM_PLAYBACK);

	if (!pcm)

		pcm = snd_lookup_minor_data(minor, SNDRV_DEVICE_TYPE_PCM_CAPTURE);

	if (!pcm)

		return false;

	snd_card_unref(pcm->card);

	return true;

}



/*
@@ -1947,7 +1980,8 @@ static int snd_pcm_link(struct snd_pcm_substream *substream, int fd) 
	int res = 0;

	struct snd_pcm_file *pcm_file;

	struct snd_pcm_substream *substream1;

	struct snd_pcm_group *group;

	struct snd_pcm_group *group, *target_group;

	bool nonatomic = substream->pcm->nonatomic;

	struct fd f = fdget(fd);



	if (!f.file)
@@ -1958,13 +1992,14 @@ static int snd_pcm_link(struct snd_pcm_substream *substream, int fd) 
	}

	pcm_file = f.file->private_data;

	substream1 = pcm_file->substream;

	group = kmalloc(sizeof(*group), GFP_KERNEL);

	group = kzalloc(sizeof(*group), GFP_KERNEL);

	if (!group) {

		res = -ENOMEM;

		goto _nolock;

	}

	down_write_nonfifo(&snd_pcm_link_rwsem);

	write_lock_irq(&snd_pcm_link_rwlock);

	snd_pcm_group_init(group);



	down_write(&snd_pcm_link_rwsem);

	if (substream->runtime->status->state == SNDRV_PCM_STATE_OPEN ||

	    substream->runtime->status->state != substream1->runtime->status->state ||

	    substream->pcm->nonatomic != substream1->pcm->nonatomic) {
@@ -1975,23 +2010,23 @@ static int snd_pcm_link(struct snd_pcm_substream *substream, int fd) 
		res = -EALREADY;

		goto _end;

	}



	snd_pcm_stream_lock_irq(substream);

	if (!snd_pcm_stream_linked(substream)) {

		substream->group = group;

		group = NULL;

		spin_lock_init(&substream->group->lock);

		mutex_init(&substream->group->mutex);

		INIT_LIST_HEAD(&substream->group->substreams);

		list_add_tail(&substream->link_list, &substream->group->substreams);

		substream->group->count = 1;

	}

	list_add_tail(&substream1->link_list, &substream->group->substreams);

	substream->group->count++;

	substream1->group = substream->group;

		snd_pcm_group_assign(substream, group);

		group = NULL; /* assigned, don't free this one below */

	}

	target_group = substream->group;

	snd_pcm_stream_unlock_irq(substream);



	snd_pcm_group_lock_irq(target_group, nonatomic);

	snd_pcm_stream_lock(substream1);

	snd_pcm_group_assign(substream1, target_group);

	snd_pcm_stream_unlock(substream1);

	snd_pcm_group_unlock_irq(target_group, nonatomic);

 _end:

	write_unlock_irq(&snd_pcm_link_rwlock);

	up_write(&snd_pcm_link_rwsem);

 _nolock:

	snd_card_unref(substream1->pcm->card);

	kfree(group);

 _badf:

	fdput(f);
@@ -2000,34 +2035,43 @@ static int snd_pcm_link(struct snd_pcm_substream *substream, int fd) 


static void relink_to_local(struct snd_pcm_substream *substream)

{

	substream->group = &substream->self_group;

	INIT_LIST_HEAD(&substream->self_group.substreams);

	list_add_tail(&substream->link_list, &substream->self_group.substreams);

	snd_pcm_stream_lock(substream);

	snd_pcm_group_assign(substream, &substream->self_group);

	snd_pcm_stream_unlock(substream);

}



static int snd_pcm_unlink(struct snd_pcm_substream *substream)

{

	struct snd_pcm_substream *s;

	struct snd_pcm_group *group;

	bool nonatomic = substream->pcm->nonatomic;

	bool do_free = false;

	int res = 0;



	down_write_nonfifo(&snd_pcm_link_rwsem);

	write_lock_irq(&snd_pcm_link_rwlock);

	down_write(&snd_pcm_link_rwsem);



	if (!snd_pcm_stream_linked(substream)) {

		res = -EALREADY;

		goto _end;

	}

	list_del(&substream->link_list);

	substream->group->count--;

	if (substream->group->count == 1) {	/* detach the last stream, too */

		snd_pcm_group_for_each_entry(s, substream) {

			relink_to_local(s);

			break;

		}

		kfree(substream->group);

	}



	group = substream->group;

	snd_pcm_group_lock_irq(group, nonatomic);



	relink_to_local(substream);



	/* detach the last stream, too */

	if (list_is_singular(&group->substreams)) {

		relink_to_local(list_first_entry(&group->substreams,

						 struct snd_pcm_substream,

						 link_list));

		do_free = !refcount_read(&group->refs);

	}



	snd_pcm_group_unlock_irq(group, nonatomic);

	if (do_free)

		kfree(group);



       _end:

	write_unlock_irq(&snd_pcm_link_rwlock);

	up_write(&snd_pcm_link_rwsem);

	return res;

}

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