On Mon, 01 Mar 2021 10:29:24 +0100, Anton Yakovlev wrote: > > 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? Those are already under spin_lock_irqsave() of the PCM substream lock (in the case of normal PCM operation without nonatomic flag). Takashi