kern/71382: Recursive mutex panic in sbc(4)

[Christian Weisgerber]

>Number:         71382
>Category:       kern
>Synopsis:       Recursive mutex panic in sbc(4)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Sep 04 21:40:23 GMT 2004
>Closed-Date:
>Last-Modified:
>Originator:     Christian Weisgerber
>Release:        FreeBSD 5.3-BETA2 alpha
>Organization:
>Environment:
System: FreeBSD kemoauc.mips.inka.de 5.3-BETA2 FreeBSD 5.3-BETA2 #0: Sat Sep 4 11:25:17 CEST 2004 naddy at kemoauc.mips.inka.de:/usr/obj/usr/src/sys/GENERIC alpha

>Description:

System: 5.3-BETA2/alpha.

With a Soundblaster Vibra16C soundcard (modules: sound, snd_sbc,
snd_sb16), any attempt to output sound immediately causes a kernel
panic.  The same setup used to work fine in 5.x/alpha; the problem
appeared in 5.x a few weeks ago.

panic: _mtx_lock_sleep: recursed on non-recursive mutex sbc0 @ /usr/src/sys/modules/sound/driver/sbc/../../../../dev/sound/isa/sbc.c:131

panic() at panic+0x210
_mtx_lock_sleep() at _mtx_lock_sleep+0x64
_mtx_lock_flags() at _mtx_lock_flags+0x9c
sbc_lock() at sbc_lock+0x28
sb_lock() at sb_lock+0x30
sb_cmd2() at sb_cmd2+0x30
sb_setup() at sb_setup+0x3e0
sb16chan_trigger() at sb16chan_trigger+0x34
chn_trigger() at chn_trigger+0xd0
chn_start() at chn_start+0x19c
chn_write() at chn_write+0x350
dsp_write() at dsp_write+0xd0
spec_write() at spec_write+0x204
spec_vnoperate() at spec_vnoperate+0x2c
vn_write() at vn_write+0x2c0
dofilewrite() at dofilewrite+0x110
write() at write+0x60
syscall() at syscall+0x38c

>How-To-Repeat:

>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: