Commit a41c4cb9 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: pcm: Make PCM linked list consistent while re-grouping 



Make a common helper to re-assign the PCM link using list_move() instead
of open code with manual list_del() and list_add_tail().  This assures
the consistency and we can get rid of snd_pcm_group.count field -- its
purpose is only to check whether the list is singular, and we can know
it by list_is_singular() call now.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 73365cb1

include/sound/pcm.h

+0 −1
Original line number Diff line number Diff line
@@ -439,7 +439,6 @@ struct snd_pcm_group { /* keep linked substreams */ 
	spinlock_t lock;

	struct mutex mutex;

	struct list_head substreams;

	int count;

};



struct pid;

sound/core/pcm_native.c

+20 −14
Original line number Diff line number Diff line
@@ -1131,6 +1131,13 @@ 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);

}



/*

 *  Note: call with stream lock

 */
@@ -1995,14 +2002,10 @@ static int snd_pcm_link(struct snd_pcm_substream *substream, int fd) 
		goto _end;

	}

	if (!snd_pcm_stream_linked(substream)) {

		substream->group = group;

		snd_pcm_group_assign(substream, group);

		group = NULL;

		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(substream1, substream->group);

 _end:

	write_unlock_irq(&snd_pcm_link_rwlock);

	up_write(&snd_pcm_link_rwsem);
@@ -2015,14 +2018,13 @@ 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_group_assign(substream, &substream->self_group);

}



static int snd_pcm_unlink(struct snd_pcm_substream *substream)

{

	struct snd_pcm_substream *s;

	struct snd_pcm_group *group;

	int res = 0;



	down_write_nonfifo(&snd_pcm_link_rwsem);
@@ -2031,16 +2033,20 @@ static int snd_pcm_unlink(struct snd_pcm_substream *substream) 
		res = -EALREADY;

		goto _end;

	}

	list_del(&substream->link_list);

	substream->group->count--;

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



	group = substream->group;



	relink_to_local(substream);



	/* detach the last stream, too */

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

		snd_pcm_group_for_each_entry(s, substream) {

			relink_to_local(s);

			break;

		}

		kfree(substream->group);

		kfree(group);

	}

	relink_to_local(substream);



       _end:

	write_unlock_irq(&snd_pcm_link_rwlock);

	up_write(&snd_pcm_link_rwsem);

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