Re: kern/54427: panic in audio_close

[Tetsuya Isaki <isaki%pastel-flower.jp@localhost>]

At Thu,  1 Aug 2019 16:45:00 +0000 (UTC),
coypu%sdf.org@localhost wrote:
> >Description:
> What I was doing: using bluetooth for an audio headset.
> 
> bta2dpd -a headset /dev/pad
> audioplay -d /dev/sound2 sample.wav

Yeah this is reproducible easily and I've stucked.

-----
#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
int main(int ac, char *av[])
{
	const char *devaudio = "/dev/audio1";	/* set your device */
	int fdpad;
	int fdaudio;
	int r;

	fdpad = open("/dev/pad", O_RDONLY);
	if (fdpad == -1)
		err(1, "open: dev/pad");

	
	fdaudio = open(devaudio, O_WRONLY);
	if (fdaudio == -1)
		err(1, "open: dev/audio");

	close(fdpad);
	close(fdaudio);
	return 0;
}
-----

First, when pad is closed, audiodetach is called from pad_close
but it doesn't close any associated audio descriptors.
When audio is closed then, pad(lower layer)'s resources are
no longer available.

I wonder why this code does not close descriptors...

sys/dev/audio/audio.c:
   1219 audiodetach(device_t self, int flags)
   1220 {
      :
   1252     /*
   1253      * Nuke the vnodes for any open instances (calls close).
   1254      * Will wait until any activity on the device nodes has ceased.
   1255      */
   1256     mn = device_unit(self);
   1257     vdevgone(maj, mn | SOUND_DEVICE,    mn | SOUND_DEVICE, VCHR);
   1258     vdevgone(maj, mn | AUDIO_DEVICE,    mn | AUDIO_DEVICE, VCHR);
   1259     vdevgone(maj, mn | AUDIOCTL_DEVICE, mn | AUDIOCTL_DEVICE, VCHR);
   1260     vdevgone(maj, mn | MIXER_DEVICE,    mn | MIXER_DEVICE, VCHR);
 
---
Tetsuya Isaki <isaki%pastel-flower.jp@localhost / isaki%NetBSD.org@localhost>