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ALSA: pcm: Use deferred fasync helper 

For avoiding the potential deadlock via kill_fasync() call, use the
new fasync helpers to defer the invocation from timer API.  Note that
it's merely a workaround.

Reported-by: syzbot+8285e973a41b5aa68902@syzkaller.appspotmail.com
Reported-by: syzbot+669c9abf11a6a011dd09@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20220728125945.29533-4-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2022-07-28 14:59:44 +02:00
parent 95cc637c1a
commit 96b097091c
4 changed files with 4 additions and 3 deletions
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2
include/sound/pcm.h
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@ -399,7 +399,7 @@ struct snd_pcm_runtime {
snd_pcm_uframes_t twake; /* do transfer (!poll) wakeup if non-zero */
wait_queue_head_t sleep; /* poll sleep */
wait_queue_head_t tsleep; /* transfer sleep */
struct fasync_struct *fasync;
struct snd_fasync *fasync;
bool stop_operating; /* sync_stop will be called */
struct mutex buffer_mutex; /* protect for buffer changes */
atomic_t buffer_accessing; /* >0: in r/w operation, <0: blocked */

1
sound/core/pcm.c
View File

@ -1007,6 +1007,7 @@ void snd_pcm_detach_substream(struct snd_pcm_substream *substream)
substream->runtime = NULL;
}
mutex_destroy(&runtime->buffer_mutex);
snd_fasync_free(runtime->fasync);
kfree(runtime);
put_pid(substream->pid);
substream->pid = NULL;

2
sound/core/pcm_lib.c
View File

@ -1822,7 +1822,7 @@ void snd_pcm_period_elapsed_under_stream_lock(struct snd_pcm_substream *substrea
snd_timer_interrupt(substream->timer, 1);
#endif
_end:
kill_fasync(&runtime->fasync, SIGIO, POLL_IN);
snd_kill_fasync(runtime->fasync, SIGIO, POLL_IN);
}
EXPORT_SYMBOL(snd_pcm_period_elapsed_under_stream_lock);

2
sound/core/pcm_native.c
View File

@ -3951,7 +3951,7 @@ static int snd_pcm_fasync(int fd, struct file * file, int on)
runtime = substream->runtime;
if (runtime->status->state == SNDRV_PCM_STATE_DISCONNECTED)
return -EBADFD;
return fasync_helper(fd, file, on, &runtime->fasync);
return snd_fasync_helper(fd, file, on, &runtime->fasync);
}
/*