Audio subsystem versus unplugging uaudio

[Julian Coleman <jdc%coris.org.uk@localhost>]

Hi,

Testing ohci recently, I came across a problem where our audio stack doesn't
handle removing an audio device whilst it's open.  I connected a uaudio
device (dmesg below), ran mplayer:

  :; mplayer -ao oss:device=/dev/audio1 track.ogg

and removed the uaudio device in the middle of the track.  This resulted in
an endless stream (roughly once every 5 seconds) of:

  audio1: audio_unlink: cv_timedwait_sig failed 35

and no USB device was recognised on that (phtsical) port.  Also, when I
connected the uaudio device to another port, it kept incrementing the
device number - uaudio1/audio2, uaudio2/audio1, etc.

Finally, when rebooting, I saw:

  panic: kernel diagnostic assertion "(target->prt_class == class)" failed: file "/usr/src/sys/kern/subr_psref.c", line 519 mismatched psref target class: 0x0 (ref) != 0x106eba700 (expected)

with a backtrace:

  db{0}> bt
  kern_assert(1adcb08, 1a370f0, 1adcae8, 1adc9d0, 207, 0) at netbsd:kern_assert+0x34
  psref_target_destroy(109591e88, 106eba700, 1092688c0, 1a37100, 109591e70, e0048000) at netbsd:psref_target_destroy+0xf8
  audiodetach(109591640, 4, ff070000000001, 109591e70, 0, 109591cc0) at netbsd:audiodetach+0xb8
  config_detach(109591640, 4, 1c7b400, 1a37100, 1c70240, 1c3c220) at netbsd:config_detach+0x90
    ...

The devices that I tested with were:

  ohci0 at pci0 dev 5 function 3: Sun Microsystems USB Controller (rev. 0x01)
  ohci0: interrupting at ivec 21f
  ohci0: OHCI version 1.0, legacy support
  usb0 at ohci0: USB revision 1.0

  ohci1 at pci0 dev 2 function 0: Acer Labs M5237 USB 1.1 Host Controller (rev. 0x03)
  ohci1: interrupting at ivec 211
  ohci1: OHCI version 1.0, legacy support
  usb1 at ohci1: USB revision 1.0
  ohci2 at pci0 dev 2 function 1: Acer Labs M5237 USB 1.1 Host Controller (rev. 0x03)
  ohci2: interrupting at ivec 211
  ohci2: OHCI version 1.0, legacy support
  usb2 at ohci2: USB revision 1.0
  ehci0 at pci0 dev 2 function 3: Acer Labs M5239 USB 2.0 Host Controller (rev. 0x01)
  ehci0: interrupting at ivec 210
  ehci0: 2 companion controllers, 2 ports each: ohci1 ohci2
  usb3 at ehci0: USB revision 2.0

  uaudio0 at uhub0 port 4 configuration 1 interface 0
  uaudio0: Logitech (0x046d) Logitech USB Headset (0x0a01), rev 1.10/10.13, addr 2
  uaudio0: ignored input endpoint of type adaptive
  uaudio0: audio rev 1.00
  audio1 at uaudio0: playback
  audio1: slinear_be:16 -> slinear_le:16 2ch 48000Hz, blk 11520 bytes (60ms) for playback
  spkr1 at audio1: PC Speaker (synthesized)
  wsbell at spkr1 not configured

Regards,

Julian