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| author | Takashi Iwai <tiwai@suse.de> | 2018-11-29 08:02:49 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-13 09:16:16 +0100 |
| commit | 19054c18846ec5fb0820febae3bfea4cac05d6e8 (patch) | |
| tree | fd899035dea3b1d6772225c7eb53db0645d957f8 | |
| parent | 026fdecbc3d79bce37d46290305cb69df4ca2711 (diff) | |
| download | linux-stable-19054c18846ec5fb0820febae3bfea4cac05d6e8.tar.gz linux-stable-19054c18846ec5fb0820febae3bfea4cac05d6e8.tar.bz2 linux-stable-19054c18846ec5fb0820febae3bfea4cac05d6e8.zip | |
ALSA: pcm: Call snd_pcm_unlink() conditionally at closing
commit b51abed8355e5556886623b2772fa6b7598d2282 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | sound/core/pcm_native.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index bdca0e10bebe..818dff1de545 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -2370,7 +2370,8 @@ 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) |