This is a note to let you know that I've just added the patch titled
ALSA: pcm: Allow aborting mutex lock at OSS read/write loops
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
alsa-pcm-allow-aborting-mutex-lock-at-oss-read-write-loops.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 900498a34a3ac9c611e9b425094c8106bdd7dc1c Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@xxxxxxx>
Date: Mon, 8 Jan 2018 14:03:53 +0100
Subject: ALSA: pcm: Allow aborting mutex lock at OSS read/write loops
From: Takashi Iwai <tiwai@xxxxxxx>
commit 900498a34a3ac9c611e9b425094c8106bdd7dc1c upstream.
PCM OSS read/write loops keep taking the mutex lock for the whole
read/write, and this might take very long when the exceptionally high
amount of data is given. Also, since it invokes with mutex_lock(),
the concurrent read/write becomes unbreakable.
This patch tries to address these issues by replacing mutex_lock()
with mutex_lock_interruptible(), and also splits / re-takes the lock
at each read/write period chunk, so that it can switch the context
more finely if requested.
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/core/oss/pcm_oss.c | 36 +++++++++++++++++++++---------------
1 file changed, 21 insertions(+), 15 deletions(-)
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -1370,8 +1370,11 @@ static ssize_t snd_pcm_oss_write1(struct
if ((tmp = snd_pcm_oss_make_ready(substream)) < 0)
return tmp;
- mutex_lock(&runtime->oss.params_lock);
while (bytes > 0) {
+ if (mutex_lock_interruptible(&runtime->oss.params_lock)) {
+ tmp = -ERESTARTSYS;
+ break;
+ }
if (bytes < runtime->oss.period_bytes || runtime->oss.buffer_used > 0) {
tmp = bytes;
if (tmp + runtime->oss.buffer_used > runtime->oss.period_bytes)
@@ -1415,18 +1418,18 @@ static ssize_t snd_pcm_oss_write1(struct
xfer += tmp;
if ((substream->f_flags & O_NONBLOCK) != 0 &&
tmp != runtime->oss.period_bytes)
- break;
+ tmp = -EAGAIN;
}
+ err:
+ mutex_unlock(&runtime->oss.params_lock);
+ if (tmp < 0)
+ break;
if (signal_pending(current)) {
tmp = -ERESTARTSYS;
- goto err;
+ break;
}
+ tmp = 0;
}
- mutex_unlock(&runtime->oss.params_lock);
- return xfer;
-
- err:
- mutex_unlock(&runtime->oss.params_lock);
return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp;
}
@@ -1474,8 +1477,11 @@ static ssize_t snd_pcm_oss_read1(struct
if ((tmp = snd_pcm_oss_make_ready(substream)) < 0)
return tmp;
- mutex_lock(&runtime->oss.params_lock);
while (bytes > 0) {
+ if (mutex_lock_interruptible(&runtime->oss.params_lock)) {
+ tmp = -ERESTARTSYS;
+ break;
+ }
if (bytes < runtime->oss.period_bytes || runtime->oss.buffer_used > 0) {
if (runtime->oss.buffer_used == 0) {
tmp = snd_pcm_oss_read2(substream, runtime->oss.buffer, runtime->oss.period_bytes, 1);
@@ -1506,16 +1512,16 @@ static ssize_t snd_pcm_oss_read1(struct
bytes -= tmp;
xfer += tmp;
}
+ err:
+ mutex_unlock(&runtime->oss.params_lock);
+ if (tmp < 0)
+ break;
if (signal_pending(current)) {
tmp = -ERESTARTSYS;
- goto err;
+ break;
}
+ tmp = 0;
}
- mutex_unlock(&runtime->oss.params_lock);
- return xfer;
-
- err:
- mutex_unlock(&runtime->oss.params_lock);
return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp;
}
Patches currently in stable-queue which might be from tiwai@xxxxxxx are
queue-3.18/alsa-pcm-remove-incorrect-snd_bug_on-usages.patch
queue-3.18/alsa-aloop-fix-inconsistent-format-due-to-incomplete-rule.patch
queue-3.18/alsa-pcm-add-missing-error-checks-in-oss-emulation-plugin-builder.patch
queue-3.18/alsa-pcm-abort-properly-at-pending-signal-in-oss-read-write-loops.patch
queue-3.18/alsa-pcm-allow-aborting-mutex-lock-at-oss-read-write-loops.patch
queue-3.18/alsa-aloop-fix-racy-hw-constraints-adjustment.patch
queue-3.18/alsa-aloop-release-cable-upon-open-error-path.patch