Commit 901d46d5 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: pcm - Fix race with proc files 



The PCM proc files may open a race against substream close, which can
end up with an Oops.  Use the open_mutex to protect for it.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 8699a0b6

sound/core/pcm.c

+24 −9
Original line number Diff line number Diff line
@@ -372,14 +372,17 @@ static void snd_pcm_substream_proc_hw_params_read(struct snd_info_entry *entry, 
						  struct snd_info_buffer *buffer)

{

	struct snd_pcm_substream *substream = entry->private_data;

	struct snd_pcm_runtime *runtime = substream->runtime;

	struct snd_pcm_runtime *runtime;



	mutex_lock(&substream->pcm->open_mutex);

	runtime = substream->runtime;

	if (!runtime) {

		snd_iprintf(buffer, "closed\n");

		return;

		goto unlock;

	}

	if (runtime->status->state == SNDRV_PCM_STATE_OPEN) {

		snd_iprintf(buffer, "no setup\n");

		return;

		goto unlock;

	}

	snd_iprintf(buffer, "access: %s\n", snd_pcm_access_name(runtime->access));

	snd_iprintf(buffer, "format: %s\n", snd_pcm_format_name(runtime->format));
@@ -398,20 +401,25 @@ static void snd_pcm_substream_proc_hw_params_read(struct snd_info_entry *entry, 
		snd_iprintf(buffer, "OSS period frames: %lu\n", (unsigned long)runtime->oss.period_frames);

	}

#endif

 unlock:

	mutex_unlock(&substream->pcm->open_mutex);

}



static void snd_pcm_substream_proc_sw_params_read(struct snd_info_entry *entry,

						  struct snd_info_buffer *buffer)

{

	struct snd_pcm_substream *substream = entry->private_data;

	struct snd_pcm_runtime *runtime = substream->runtime;

	struct snd_pcm_runtime *runtime;



	mutex_lock(&substream->pcm->open_mutex);

	runtime = substream->runtime;

	if (!runtime) {

		snd_iprintf(buffer, "closed\n");

		return;

		goto unlock;

	}

	if (runtime->status->state == SNDRV_PCM_STATE_OPEN) {

		snd_iprintf(buffer, "no setup\n");

		return;

		goto unlock;

	}

	snd_iprintf(buffer, "tstamp_mode: %s\n", snd_pcm_tstamp_mode_name(runtime->tstamp_mode));

	snd_iprintf(buffer, "period_step: %u\n", runtime->period_step);
@@ -421,24 +429,29 @@ static void snd_pcm_substream_proc_sw_params_read(struct snd_info_entry *entry, 
	snd_iprintf(buffer, "silence_threshold: %lu\n", runtime->silence_threshold);

	snd_iprintf(buffer, "silence_size: %lu\n", runtime->silence_size);

	snd_iprintf(buffer, "boundary: %lu\n", runtime->boundary);

 unlock:

	mutex_unlock(&substream->pcm->open_mutex);

}



static void snd_pcm_substream_proc_status_read(struct snd_info_entry *entry,

					       struct snd_info_buffer *buffer)

{

	struct snd_pcm_substream *substream = entry->private_data;

	struct snd_pcm_runtime *runtime = substream->runtime;

	struct snd_pcm_runtime *runtime;

	struct snd_pcm_status status;

	int err;



	mutex_lock(&substream->pcm->open_mutex);

	runtime = substream->runtime;

	if (!runtime) {

		snd_iprintf(buffer, "closed\n");

		return;

		goto unlock;

	}

	memset(&status, 0, sizeof(status));

	err = snd_pcm_status(substream, &status);

	if (err < 0) {

		snd_iprintf(buffer, "error %d\n", err);

		return;

		goto unlock;

	}

	snd_iprintf(buffer, "state: %s\n", snd_pcm_state_name(status.state));

	snd_iprintf(buffer, "owner_pid   : %d\n", pid_vnr(substream->pid));
@@ -452,6 +465,8 @@ static void snd_pcm_substream_proc_status_read(struct snd_info_entry *entry, 
	snd_iprintf(buffer, "-----\n");

	snd_iprintf(buffer, "hw_ptr      : %ld\n", runtime->status->hw_ptr);

	snd_iprintf(buffer, "appl_ptr    : %ld\n", runtime->control->appl_ptr);

 unlock:

	mutex_unlock(&substream->pcm->open_mutex);

}



#ifdef CONFIG_SND_PCM_XRUN_DEBUG