Re: [PATCH 2/2] ALSA: pcm: auto-fill buffer with silence when draining playback

[Takashi Iwai <tiwai@suse.de>]

On Wed, 12 Apr 2023 10:04:31 +0200,
Oswald Buddenhagen wrote:
> 
> On Wed, Apr 12, 2023 at 09:54:54AM +0200, Takashi Iwai wrote:
> > I'm thinking whether we need to change anything in the kernel side for
> > this at all.  Can't it be changed rather in alsa-lib side instead?
> > 
> it could, but it would be a lot uglier. user space would have to do a
> "man-in-the-middle attack" on the data, while in the kernel we can
> just slightly modify the consumer. this would be particularly obvious
> in the case of write() access.

But basically it'd be like fiddling sw_params temporarily for
draining, I suppose?  And the "attack" here can be taken too
seriously; the whole PCM operation can be somehow interfered if a
process may have the access to the PCM device, and changing sw_params
itself must not introduce too much trouble.


thanks,

Takashi