kern/43884: subr_log.c: Mutex error: lockdebug_wantlock: locking against myself

[Christoph_Egger%gmx.de@localhost]

>Number:         43884
>Category:       kern
>Synopsis:       subr_log.c: Mutex error: lockdebug_wantlock: locking against 
>myself
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Sep 16 09:50:00 +0000 2010
>Originator:     Christoph Egger
>Release:        NeBSD-current
>Organization:
>Environment:
>Description:

I got this LOCKDEBUG panic:

Mutex error: lockdebug_wantlock: locking against myself

lock address : 0xffffffff80cb2a90 type     :               spin
initialized  : 0xffffffff805bd764
shared holds :                  0 exclusive:                  1
shares wanted:                  0 exclusive:                  1
current cpu  :                  0 last held:                  0
current lwp  : 0xffffa0002591f640 last held: 0xffffa0002591f640
last locked  : 0xffffffff805bd5e2 unlocked : 0xffffffff805bd35a
owner field  : 0x0000000000010600 wait/spin:                0/1

panic: LOCKDEBUG

'last locked' points to function sys/kern/subr_log.c:logread

mutex_spin_enter(&log_lock);

'unlocked' points to function sys/kern/subr_log.c:filt_logread

mutex_spin_exit(&log_lock);

The backtrace:

breakpoint() at netbsd:breakpoint+0x5
panic() at netbsd:panic+0x28f
lockdebug_more() at netbsd:lockdebug_more
mutex_enter() at netbsd:mutex_enter+0x263
logputchar() at netbsd:logputchar+0x68
putchar() at netbsd:putchar+0x95
kprintf() at netbsd:kprintf+0x1d2
printf() at netbsd:printf+0xb7


The 'logputchar+0x68' points to sys/kern/subr_log.c:logputchar

  mutex_spin_enter(&log_lock);


>How-To-Repeat:

>Fix: