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ALSA: pcm: Fix mutex unbalance in OSS emulation ioctls

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The previous fix 40cab6e88c ("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: 40cab6e88c ("ALSA: pcm: Return -EBUSY for OSS ioctls changing busy streams")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2018-03-27 14:32:23 +02:00
parent 306a4f3ca7
commit f6d297df4d
1 changed files with 42 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

67
sound/core/oss/pcm_oss.c
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@ -823,6 +823,23 @@ 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)
{
@ -1721,6 +1738,8 @@ 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;
@ -1728,15 +1747,14 @@ 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);
}
@ -1761,18 +1779,19 @@ 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);
}
@ -1845,6 +1864,7 @@ 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);
@ -1858,15 +1878,14 @@ 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);
@ -1914,12 +1933,11 @@ 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;
}
@ -1954,12 +1972,11 @@ 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;
}