Re: [alsa-devel] [PATCH 04/10] ALSA: aloop: Use always spin_lock_irqsave() for cable->lock

On Mon, 25 Mar 2019 17:00:38 +0100, twischer@de.adit-jv.com wrote:

From: Timo Wischer twischer@de.adit-jv.com

to allow the usage of timer callbacks from interrupt context. For example the sound timer.

The trigger callback is already irq-disabled. And, open/close must not be irq-disabled OTOH. So these changes must be superfluous.

thanks,

Takashi

Signed-off-by: Timo Wischer twischer@de.adit-jv.com

sound/drivers/aloop.c | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-)

diff --git a/sound/drivers/aloop.c b/sound/drivers/aloop.c index 11e8ed6..c6217c4 100644 --- a/sound/drivers/aloop.c +++ b/sound/drivers/aloop.c @@ -272,6 +272,7 @@ static int loopback_trigger(struct snd_pcm_substream *substream, int cmd) struct loopback_pcm *dpcm = runtime->private_data; struct loopback_cable *cable = dpcm->cable; int err = 0, stream = 1 << substream->stream;

• unsigned long flags;

  switch (cmd) { case SNDRV_PCM_TRIGGER_START:

@@ -281,39 +282,39 @@ static int loopback_trigger(struct snd_pcm_substream *substream, int cmd) dpcm->last_jiffies = jiffies; dpcm->pcm_rate_shift = 0; dpcm->last_drift = 0;

• spin_lock(&cable->lock);	
  

• spin_lock_irqsave(&cable->lock, flags);
  

  cable->running |= stream; cable->pause &= ~stream; err = loopback_timer_start(dpcm);

• spin_unlock(&cable->lock);
  

• spin_unlock_irqrestore(&cable->lock, flags);
  

  if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) loopback_active_notify(dpcm); break; case SNDRV_PCM_TRIGGER_STOP:

• spin_lock(&cable->lock);	
  

• spin_lock_irqsave(&cable->lock, flags);
  

  cable->running &= ~stream; cable->pause &= ~stream; err = loopback_timer_stop(dpcm);

• spin_unlock(&cable->lock);
  

• spin_unlock_irqrestore(&cable->lock, flags);
  

  if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) loopback_active_notify(dpcm); break; case SNDRV_PCM_TRIGGER_PAUSE_PUSH: case SNDRV_PCM_TRIGGER_SUSPEND:

• spin_lock(&cable->lock);	
  

• spin_lock_irqsave(&cable->lock, flags);
  

  cable->pause |= stream; err = loopback_timer_stop(dpcm);

• spin_unlock(&cable->lock);
  

• spin_unlock_irqrestore(&cable->lock, flags);
  

  if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) loopback_active_notify(dpcm); break; case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: case SNDRV_PCM_TRIGGER_RESUME:

• spin_lock(&cable->lock);
  

• spin_lock_irqsave(&cable->lock, flags);
  

  dpcm->last_jiffies = jiffies; cable->pause &= ~stream; err = loopback_timer_start(dpcm);

• spin_unlock(&cable->lock);
  

• spin_unlock_irqrestore(&cable->lock, flags);
  

  if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) loopback_active_notify(dpcm); break;

@@ -557,12 +558,13 @@ static snd_pcm_uframes_t loopback_pointer(struct snd_pcm_substream *substream) { struct snd_pcm_runtime *runtime = substream->runtime; struct loopback_pcm *dpcm = runtime->private_data;

• unsigned long flags; snd_pcm_uframes_t pos;

• spin_lock(&dpcm->cable->lock);

• spin_lock_irqsave(&dpcm->cable->lock, flags); loopback_pos_update(dpcm->cable); pos = dpcm->buf_pos;

• spin_unlock(&dpcm->cable->lock);

• spin_unlock_irqrestore(&dpcm->cable->lock, flags); return bytes_to_frames(runtime, pos);

}

@@ -679,10 +681,12 @@ static void free_cable(struct snd_pcm_substream *substream) if (!cable) return; if (cable->streams[!substream->stream]) {

• unsigned long flags;
  

• /* other stream is still alive */

• spin_lock_irq(&cable->lock);
  

• spin_lock_irqsave(&cable->lock, flags);
  

  cable->streams[substream->stream] = NULL;

• spin_unlock_irq(&cable->lock);
  

• spin_unlock_irqrestore(&cable->lock, flags);
  

  } else { /* free the cable */ loopback->cables[substream->number][dev] = NULL;

@@ -698,6 +702,7 @@ static int loopback_open(struct snd_pcm_substream *substream) struct loopback_cable *cable = NULL; int err = 0; int dev = get_cable_index(substream);

• unsigned long flags;

  mutex_lock(&loopback->cable_lock); dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);

@@ -753,9 +758,9 @@ static int loopback_open(struct snd_pcm_substream *substream) else runtime->hw = cable->hw;

• spin_lock_irq(&cable->lock);

• spin_lock_irqsave(&cable->lock, flags); cable->streams[substream->stream] = dpcm;

• spin_unlock_irq(&cable->lock);

• spin_unlock_irqrestore(&cable->lock, flags);

  unlock: if (err < 0) {

-- 2.7.4