From 901d46d5a8eb821b03ca9e8cf005beb0c92f31ea Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Thu, 16 Sep 2010 23:06:50 +0200 Subject: [PATCH] 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: Takashi Iwai --- sound/core/pcm.c | 33 ++++++++++++++++++++++++--------- 1 file changed, 24 insertions(+), 9 deletions(-) diff --git a/sound/core/pcm.c b/sound/core/pcm.c index 204af48c5cc1..ac242a377aea 100644 --- a/sound/core/pcm.c +++ b/sound/core/pcm.c @@ -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 -- 2.20.1