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Commit 900498a3 authored by Takashi Iwai's avatar Takashi Iwai
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ALSA: pcm: Allow aborting mutex lock at OSS read/write loops 



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.

Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 29159a4e

sound/core/oss/pcm_oss.c

+21 −15
Original line number Diff line number Diff line
@@ -1334,8 +1334,11 @@ static ssize_t snd_pcm_oss_write1(struct snd_pcm_substream *substream, const cha 


	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)
@@ -1379,18 +1382,18 @@ static ssize_t snd_pcm_oss_write1(struct snd_pcm_substream *substream, const cha 
			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;

}
@@ -1438,8 +1441,11 @@ static ssize_t snd_pcm_oss_read1(struct snd_pcm_substream *substream, char __use 


	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);
@@ -1470,16 +1476,16 @@ static ssize_t snd_pcm_oss_read1(struct snd_pcm_substream *substream, char __use 
			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;

}