Re: [alsa-devel] [PATCH 3/3] sound: dummy, avoid races with timer

On 01/19/2015, 10:49 AM, Takashi Iwai wrote:

...

@@ -322,12 +325,14 @@ static snd_pcm_uframes_t dummy_systimer_pointer(struct snd_pcm_substream *substream) { struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;

• unsigned long flags; snd_pcm_uframes_t pos;

• spin_lock(&dpcm->lock);

• spin_lock_irqsave(&dpcm->lock, flags); dummy_systimer_update(dpcm); pos = dpcm->frac_pos / HZ;

• spin_unlock(&dpcm->lock);

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

This chunk is superfluous. The pointer callback is guaranteed to be called in the irq-disabled context.

Oh, my bad, I was looking at snd_compr_ops->pointer which is not the case.