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authorTakashi Iwai <tiwai@suse.de>2018-11-29 08:02:49 +0100
committerTakashi Iwai <tiwai@suse.de>2018-11-29 08:14:52 +0100
commitb51abed8355e5556886623b2772fa6b7598d2282 (patch)
parent8159a6a4a7d2a092d5375f695ecfca22b4562b5f (diff)
ALSA: pcm: Call snd_pcm_unlink() conditionally at closing
Currently the PCM core calls snd_pcm_unlink() always unconditionally at closing a stream. However, since snd_pcm_unlink() invokes the global rwsem down, the lock can be easily contended. More badly, when a thread runs in a high priority RT-FIFO, it may stall at spinning. Basically the call of snd_pcm_unlink() is required only for the linked streams that are already rare occasion. For normal use cases, this code path is fairly superfluous. As an optimization (and also as a workaround for the RT problem above in normal situations without linked streams), this patch adds a check before calling snd_pcm_unlink() and calls it only when needed. Reported-by: Chanho Min <chanho.min@lge.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
1 files changed, 2 insertions, 1 deletions
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 66c90f486af9..6afcc393113a 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -2369,7 +2369,8 @@ int snd_pcm_hw_constraints_complete(struct snd_pcm_substream *substream)
static void pcm_release_private(struct snd_pcm_substream *substream)
- snd_pcm_unlink(substream);
+ if (snd_pcm_stream_linked(substream))
+ snd_pcm_unlink(substream);
void snd_pcm_release_substream(struct snd_pcm_substream *substream)