Re: locking against myself

From: Jerry Toung (jtoung_at_arc.nasa.gov)
Date: 02/19/04

  • Next message: Ted Unangst: "use after free bugs" 
    To: Andrey Simonenko <simon@comsys.ntu-kpi.kiev.ua>
Date: Thu, 19 Feb 2004 07:37:48 -0800

    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 Debugger+0x54: xchgl %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
    > lock is already held, and LK_CANRECURSE is not
    > set, the system will panic(9). 

    -- 
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