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Commit 24fd21ae authored by Takashi Iwai's avatar Takashi Iwai Committed by Greg Kroah-Hartman
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ALSA: pcm: Fix mutex unbalance in OSS emulation ioctls 



commit f6d297df4dd47ef949540e4a201230d0c5308325 upstream.

The previous fix 40cab6e88cb0 ("ALSA: pcm: Return -EBUSY for OSS
ioctls changing busy streams") introduced some mutex unbalance; the
check of runtime->oss.rw_ref was inserted in a wrong place after the
mutex lock.

This patch fixes the inconsistency by rewriting with the helper
functions to lock/unlock parameters with the stream check.

Fixes: 40cab6e88cb0 ("ALSA: pcm: Return -EBUSY for OSS ioctls changing busy streams")
Reported-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3724f9c7

sound/core/oss/pcm_oss.c

+42 −25
Original line number Diff line number Diff line
@@ -834,6 +834,23 @@ static int choose_rate(struct snd_pcm_substream *substream, 
	return snd_pcm_hw_param_near(substream, params, SNDRV_PCM_HW_PARAM_RATE, best_rate, NULL);

}



/* parameter locking: returns immediately if tried during streaming */

static int lock_params(struct snd_pcm_runtime *runtime)

{

	if (mutex_lock_interruptible(&runtime->oss.params_lock))

		return -ERESTARTSYS;

	if (atomic_read(&runtime->oss.rw_ref)) {

		mutex_unlock(&runtime->oss.params_lock);

		return -EBUSY;

	}

	return 0;

}



static void unlock_params(struct snd_pcm_runtime *runtime)

{

	mutex_unlock(&runtime->oss.params_lock);

}



/* call with params_lock held */

static int snd_pcm_oss_change_params_locked(struct snd_pcm_substream *substream)

{
@@ -1773,6 +1790,8 @@ static int snd_pcm_oss_set_rate(struct snd_pcm_oss_file *pcm_oss_file, int rate) 
	for (idx = 1; idx >= 0; --idx) {

		struct snd_pcm_substream *substream = pcm_oss_file->streams[idx];

		struct snd_pcm_runtime *runtime;

		int err;



		if (substream == NULL)

			continue;

		runtime = substream->runtime;
@@ -1780,15 +1799,14 @@ static int snd_pcm_oss_set_rate(struct snd_pcm_oss_file *pcm_oss_file, int rate) 
			rate = 1000;

		else if (rate > 192000)

			rate = 192000;

		if (mutex_lock_interruptible(&runtime->oss.params_lock))

			return -ERESTARTSYS;

		if (atomic_read(&runtime->oss.rw_ref))

			return -EBUSY;

		err = lock_params(runtime);

		if (err < 0)

			return err;

		if (runtime->oss.rate != rate) {

			runtime->oss.params = 1;

			runtime->oss.rate = rate;

		}

		mutex_unlock(&runtime->oss.params_lock);

		unlock_params(runtime);

	}

	return snd_pcm_oss_get_rate(pcm_oss_file);

}
@@ -1813,18 +1831,19 @@ static int snd_pcm_oss_set_channels(struct snd_pcm_oss_file *pcm_oss_file, unsig 
	for (idx = 1; idx >= 0; --idx) {

		struct snd_pcm_substream *substream = pcm_oss_file->streams[idx];

		struct snd_pcm_runtime *runtime;

		int err;



		if (substream == NULL)

			continue;

		runtime = substream->runtime;

		if (mutex_lock_interruptible(&runtime->oss.params_lock))

			return -ERESTARTSYS;

		if (atomic_read(&runtime->oss.rw_ref))

			return -EBUSY;

		err = lock_params(runtime);

		if (err < 0)

			return err;

		if (runtime->oss.channels != channels) {

			runtime->oss.params = 1;

			runtime->oss.channels = channels;

		}

		mutex_unlock(&runtime->oss.params_lock);

		unlock_params(runtime);

	}

	return snd_pcm_oss_get_channels(pcm_oss_file);

}
@@ -1897,6 +1916,7 @@ static int snd_pcm_oss_get_formats(struct snd_pcm_oss_file *pcm_oss_file) 
static int snd_pcm_oss_set_format(struct snd_pcm_oss_file *pcm_oss_file, int format)

{

	int formats, idx;

	int err;

	

	if (format != AFMT_QUERY) {

		formats = snd_pcm_oss_get_formats(pcm_oss_file);
@@ -1910,15 +1930,14 @@ static int snd_pcm_oss_set_format(struct snd_pcm_oss_file *pcm_oss_file, int for 
			if (substream == NULL)

				continue;

			runtime = substream->runtime;

			if (atomic_read(&runtime->oss.rw_ref))

				return -EBUSY;

			if (mutex_lock_interruptible(&runtime->oss.params_lock))

				return -ERESTARTSYS;

			err = lock_params(runtime);

			if (err < 0)

				return err;

			if (runtime->oss.format != format) {

				runtime->oss.params = 1;

				runtime->oss.format = format;

			}

			mutex_unlock(&runtime->oss.params_lock);

			unlock_params(runtime);

		}

	}

	return snd_pcm_oss_get_format(pcm_oss_file);
@@ -1966,12 +1985,11 @@ static int snd_pcm_oss_set_subdivide(struct snd_pcm_oss_file *pcm_oss_file, int 
		if (substream == NULL)

			continue;

		runtime = substream->runtime;

		if (atomic_read(&runtime->oss.rw_ref))

			return -EBUSY;

		if (mutex_lock_interruptible(&runtime->oss.params_lock))

			return -ERESTARTSYS;

		err = lock_params(runtime);

		if (err < 0)

			return err;

		err = snd_pcm_oss_set_subdivide1(substream, subdivide);

		mutex_unlock(&runtime->oss.params_lock);

		unlock_params(runtime);

		if (err < 0)

			return err;

	}
@@ -2006,12 +2024,11 @@ static int snd_pcm_oss_set_fragment(struct snd_pcm_oss_file *pcm_oss_file, unsig 
		if (substream == NULL)

			continue;

		runtime = substream->runtime;

		if (atomic_read(&runtime->oss.rw_ref))

			return -EBUSY;

		if (mutex_lock_interruptible(&runtime->oss.params_lock))

			return -ERESTARTSYS;

		err = lock_params(runtime);

		if (err < 0)

			return err;

		err = snd_pcm_oss_set_fragment1(substream, val);

		mutex_unlock(&runtime->oss.params_lock);

		unlock_params(runtime);

		if (err < 0)

			return err;

	}