1 Mar
2021
1 Mar
'21
2:33 p.m.
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