On 28.02.2021 12:32, Takashi Iwai wrote:> On Sat, 27 Feb 2021 09:59:53 +0100,
> Anton Yakovlev wrote:
>>
[snip]
>> +static snd_pcm_uframes_t
>> +virtsnd_pcm_pointer(struct snd_pcm_substream *substream)
>> +{
>> + struct virtio_pcm_substream *vss =
snd_pcm_substream_chip(substream);
>> + snd_pcm_uframes_t hw_ptr = SNDRV_PCM_POS_XRUN;
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&vss->lock, flags);
>> + if (!vss->xfer_xrun)
>> + hw_ptr = bytes_to_frames(substream->runtime,
vss->hw_ptr);
>> + spin_unlock_irqrestore(&vss->lock, flags);
>
> Oh, and if we drop nonatomc PCM, both trigger and pointer callbacks
> are guaranteed to be called inside the spinlock, hence you can remove
> *_irqsave() but just us spin_lock() in those two callbacks.
As I understand, spin_lock_irqsave() disables only local interrupts. But
what about other CPU cores?
>
> thanks,
>
> Takashi
>
--
Anton Yakovlev
Senior Software Engineer
OpenSynergy GmbH
Rotherstr. 20, 10245 Berlin