From owner-freebsd-hackers@FreeBSD.ORG  Thu Feb 19 07:38:42 2004
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From: Jerry Toung <jtoung@arc.nasa.gov>
To: Andrey Simonenko <simon@comsys.ntu-kpi.kiev.ua>
Date: Thu, 19 Feb 2004 07:37:48 -0800
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cc: hackers <freebsd-hackers@freebsd.org>
Subject: Re: locking against myself
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Thanks a lot Andrey.

On Thursday 19 February 2004 12:05 am, Andrey Simonenko wrote:
> On Wed, Feb 18, 2004 at 11:52:26AM -0800, Jerry Toung wrote:
> > Hello hackers,
> > I am constantly getting the following message when I run my KLD:
> >
> > panic: lockmgr: locking against myself
> > Debugger("panic")
> > Stopped at=09=09Debugger+0x54:=09=09xchgl=09=09%ebx,in_Debugger.0
> > db>
> >
> > What could possibly cause this?
> > It seem to say that I'm locking an already locked variable.
>
> Hello Jerry,
>
> According to kern/kern_lock.c:lockmgr() your proc/thread already
> has an exclusive lock and it tries to obtain a recursive exclusive
> lock and lock doesn't have LK_CANRECURSE flag (also you allow to
> sleep in lockmng()).
>
> This is documented in lock(9) manual page:
>
>        LK_EXCLUSIVE    Acquire an exclusive lock.  If an exclusive
> =09=09       lock is already held, and LK_CANRECURSE is not
> =09=09       set, the system will panic(9).

--=20