[alsa-devel] [Pkg-alsa-devel] Bug#438118: alsa-utils: aplay non-blocking mode isn't working
tiwai at suse.de
Fri Dec 14 13:41:07 CET 2007
At Fri, 14 Dec 2007 11:53:11 +0100 (CET),
Jaroslav Kysela wrote:
> On Fri, 14 Dec 2007, Anders Boström wrote:
> > >>>>> "TI" == Takashi Iwai <tiwai at suse.de> writes:
> > TI> OK, thanks, I see the problem now.
> > >>
> > TI> I don't remember whether it's a feature or a bug. The drain ioctl
> > TI> rejects the non-block mode.
> > >>
> > >> I can understand the idea here, that in non-blocking mode, no call
> > >> should block, ever. But on the other hand, if you call the drain
> > >> ioctl, you probably expect it to work, even in non-blocking mode. Why
> > >> would you otherwise call it?
> > TI> Yes, that's my opinion, too. This particular ioctl is to block the
> > TI> operation, so it should be allowed as long as it's called.
> > TI> But I vaguely remember that we discussed about it, and the current
> > TI> form is the result of that. Namely, we can call
> > TI> snd_pcm_nonblock(FALSE) explicitly before calling snd_pcm_drain().
> > TI> Though, I prefer fixing the behavior in the core side to allow the
> > TI> blocking with this call... Any reasonable objections in mind?
> > Any progress in including a solotion to this bug in mainstream
> > alsa & linux kernel? Has anything been done? The patch works fine for
> > me...
> I think that this proposal breaks basic posix rules.
AFAIK, O_NONBLOCK doesn't define the behavior of each ioctl on POSIX
at all. Some standard POSIX-defined ioctls block even with O_NONBLOCK
> Application should
> change blocking state itself. And non-blocking snd_pcm_drain() still makes
> sense - it will return state of stream (-EAGAIN - unfinished) or reset PCM
> state to SETUP in case when all data are played.
Well, this can be kept as is, but it's a bit weird (and silly)
behavior. Anyway, we'll need fix this bug in our own codes in
alsa-utils first :)
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