simple_unlock: lock not held
lock:0xcd161128, currently at: /usr/src/sys/kern/tty.c:1979 on CPU 0
last locked: /usr/src/sys/kern/tty.c:1928
last unlocked: /usr/src/sys/kern/tty.c:1949
ttywrite(cd161120,d6c83ec4,1,c3a8e100,dacb5ac0) at netbsd:ttywrite+0x6d0
wsdisplaywrite(2f00,d5c83ec4,1,2f,cde539f0) at netbsd:wsdisplaywrite 
+0x5d
cnwrite(2f00,d5c83ec4,1,c063fa20,cde539f0) at netbsd:cnwrite+0x29
spec_write(d6c83e24,989680,0,0,cde63968) at netbsd:spec_write+0xa0
ufsspec_write(d6c83e24,989680,d5c83e5c,202,c0638c40) at  
netbsD:ufsspec_write+0x3b
VOP_WRITE+0x34
vn_write+0xbd
dofilewrite+0x85
sys_write+0x75
syscall_plain+0x1a5
--- stscall (number 4) ---
0xbdb2c91b:

(gdb) bt
#0  0x00000000 in ?? ()
#1  0xc0a94000 in ?? ()
#2  0xc045866d in cpu_reboot (howto=260, bootstr=0x0)
     at /usr/src/sys/arch/i386/i386/machdep.c:752
#3  0xc035f219 in db_reboot_cmd (addr=1, have_addr=0, count=-1068153318,
     modif=0xd5c839d8 "?\t\207??9??\001") at /usr/src/sys/ddb/ 
db_command.c:694
#4  0xc035ed5f in db_command (last_cmdp=0xc07f6928,  
cmd_table=0xc0635620)
     at /usr/src/sys/ddb/db_command.c:469
#5  0xc035ea6f in db_command_loop () at /usr/src/sys/ddb/db_command.c: 
260
#6  0xc0361bb3 in db_trap (type=1, code=0) at /usr/src/sys/ddb/ 
db_trap.c:101
#7  0xc0455ba6 in kdb_trap (type=1, code=0, regs=0xd5c83c2c)
     at /usr/src/sys/arch/i386/i386/db_interface.c:225
#8  0xc0463034 in trap (frame=0xd5c83c2c)
     at /usr/src/sys/arch/i386/i386/trap.c:270
#9  0xc010bdd2 in calltrap ()
#10 0xc0393823 in _simple_unlock (alp=0xcd161128,
     id=0xc074ea9a "/usr/src/sys/kern/tty.c", l=1979)
     at /usr/src/sys/kern/kern_lock.c:1252
#11 0xc03c2f80 in ttwrite (tp=0xcd161120, uio=0xd5c83ec4, flag=1)
     at /usr/src/sys/kern/tty.c:1979
#12 0xc0552e4d in wsdisplaywrite (dev=12032, uio=0xd5c83ec4, flag=1)
     at /usr/src/sys/dev/wscons/wsdisplay.c:890
#13 0xc04641f1 in cnwrite (dev=12032, uio=0xd5c83ec4, flag=1)
---Type <return> to continue, or q <return> to quit---
     at /usr/src/sys/dev/cons.c:224
#14 0xc03eebe8 in spec_write (v=0xd5c83e24)
     at /usr/src/sys/miscfs/specfs/spec_vnops.c:390
#15 0xc035d4bf in ufsspec_write (v=0xd5c83e24)
     at /usr/src/sys/ufs/ufs/ufs_vnops.c:1821
#16 0xc03e8c60 in VOP_WRITE (vp=0xcde53968, uio=0xd5c83ec4, ioflag=1,
     cred=0xcd160000) at /usr/src/sys/kern/vnode_if.c:499
#17 0xc03e7dfd in vn_write (fp=0xcd176c30, offset=0xcd176c58,  
uio=0xd5c83ec4,
     cred=0xcd160000, flags=1) at /usr/src/sys/kern/vfs_vnops.c:486
#18 0xc03b8189 in dofilewrite (p=0xdacb5ac0, fd=1, fp=0xcd176c30,
     buf=0xbfbfd9b0, nbyte=80, offset=0xcd176c58, flags=1,  
retval=0xd5c83f5c)
     at /usr/src/sys/kern/sys_generic.c:359
#19 0xc03b80d1 in sys_write (l=0xcde988c8, v=0xd5c83f64,  
retval=0xd5c83f5c)
     at /usr/src/sys/kern/sys_generic.c:315
#20 0xc04629f9 in syscall_plain (frame=0xd5c83fa8)
     at /usr/src/sys/arch/i386/i386/syscall.c:161
(gdb)