LOR on kldunload snd_hda

log in
kldload snd_hda
cat /dev/sndstat

FreeBSD Audio Driver (newpcm: 32 bit 20090615000/i386)
Installed devices:
pcm0: <HDA Sigmatel STAC9228X PCM #0 Analog> at cad 0 nid 1 on hdac0 kld 
snd_hda
[MPSAFE] (1p:1v/1r:1v channels duplex default)

mixer
Mixer vol is currently set to 75:75
Mixer pcm is currently set to 75:75
Mixer speaker is currently set to 75:75
Mixer mic is currently set to 0:0
Mixer rec is currently set to 0:0

"insert cd"

cdcontrol -f /dev/acd0 play 1

"no sound at all"

cdcontrol eject
kldunload snd_hda

Jul  7 21:44:15 gargoyle login: ROOT LOGIN (root) ON ttyv0
Jul  7 21:54:27 gargoyle kernel: hdac0: <Intel 82801H High Definition 
Audio Controller> mem 0xf6dfc000-0xf6dfffff irq 21 at device 27.0 on 
pci0
Jul  7 21:54:27 gargoyle kernel: hdac0: HDA Driver Revision: 
20090624_0136
Jul  7 21:54:27 gargoyle kernel: hdac0: [ITHREAD]
Jul  7 21:54:27 gargoyle kernel: hdac0: HDA Codec #0: Sigmatel STAC9228X
Jul  7 21:54:27 gargoyle kernel: pcm0: <HDA Sigmatel STAC9228X PCM #0 
Analog> at cad 0 nid 1 on hdac0
Jul  7 22:03:27 gargoyle kernel: lock order reversal:
Jul  7 22:03:27 gargoyle kernel: 1st 0xc0da8cdc kernel linker (kernel 
linker) _at_ /usr/src/sys/kern/kern_linker.c:1079
Jul  7 22:03:27 gargoyle kernel: 2nd 0xc0daa4e4 sysctl lock (sysctl 
lock) _at_ /usr/src/sys/kern/kern_sysctl.c:255
Jul  7 22:03:27 gargoyle kernel: KDB: stack backtrace:
Jul  7 22:03:27 gargoyle kernel: 
db_trace_self_wrapper(c0c5b564,e6df7ac0,c08b5b35,c08a68db,c0c5e3f9,...) 
at db_trace_self_wrapper+0x26
Jul  7 22:03:27 gargoyle kernel: 
kdb_backtrace(c08a68db,c0c5e3f9,c452cae8,c452ad40,e6df7b1c,...) at 
kdb_backtrace+0x29
Jul  7 22:03:27 gargoyle kernel: 
_witness_debugger(c0c5e3f9,c0daa4e4,c0c58fbb,c452ad40,c0c58ec2,...) at 
_witness_debugger+0x25
Jul  7 22:03:27 gargoyle kernel: 
witness_checkorder(c0daa4e4,9,c0c58ec2,ff,0,...) at 
witness_checkorder+0x839
Jul  7 22:03:27 gargoyle kernel: _sx_xlock(c0daa4e4,0,c0c58ec2,ff,0,...) 
at _sx_xlock+0x85
Jul  7 22:03:27 gargoyle kernel: 
sysctl_ctx_free(c4d7379c,0,c4e1c712,4a1,c4ca9480,...) at 
sysctl_ctx_free+0x30
Jul  7 22:03:27 gargoyle kernel: 
pcm_unregister(c488f800,c4da3860,c0d3b6c8,a3c,c4887a80,...) at 
pcm_unregister+0x4e1
Jul  7 22:03:27 gargoyle kernel: 
device_detach(c488f800,c0865663,c0da9df0,c4dd22d4,c4a95100,...) at 
device_detach+0x8c
Jul  7 22:03:27 gargoyle kernel: 
driver_module_handler(c4887a80,1,c4dd22d4,109,0,...) at 
driver_module_handler+0x29c
Jul  7 22:03:27 gargoyle kernel: 
module_unload(c4887a80,c0c54c7c,273,270,c08592b6,...) at 
module_unload+0x43
Jul  7 22:03:27 gargoyle kernel: 
linker_file_unload(c4a92600,0,c0c54c7c,437,c4dba000,...) at 
linker_file_unload+0x15e
Jul  7 22:03:27 gargoyle kernel: 
kern_kldunload(c4ca9480,2,0,e6df7d2c,c0b98e73,...) at 
kern_kldunload+0xd5
Jul  7 22:03:27 gargoyle kernel: 
kldunloadf(c4ca9480,e6df7cf8,8,c0c5f4bb,c0d3f0b0,...) at 
kldunloadf+0x2b
Jul  7 22:03:27 gargoyle kernel: syscall(e6df7d38) at syscall+0x2a3
Jul  7 22:03:27 gargoyle kernel: Xint0x80_syscall() at 
Xint0x80_syscall+0x20
Jul  7 22:03:27 gargoyle kernel: --- syscall (444, FreeBSD ELF32, 
kldunloadf), eip = 0x280d573b, esp = 0xbfbfe47c, ebp = 0xbfbfecc8 ---
Jul  7 22:03:27 gargoyle kernel: pcm0: detached
Jul  7 22:03:27 gargoyle kernel: hdac0: detached

Any pointers??

Best Regards
Gonzalo
-- 
Blessings
Gonzalo Nemmi