From a41c4cb913b53bf74f1ec66a4b96057626c87009 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Sun, 13 Jan 2019 09:40:21 +0100 Subject: [PATCH] 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: Takashi Iwai --- include/sound/pcm.h | 1 - sound/core/pcm_native.c | 34 ++++++++++++++++++++-------------- 2 files changed, 20 insertions(+), 15 deletions(-) diff --git a/include/sound/pcm.h b/include/sound/pcm.h index d6bd3caf6878..e1c747c70883 100644 --- a/include/sound/pcm.h +++ b/include/sound/pcm.h @@ -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; diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 9e4e289e5703..1a56bb1ad780 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -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);