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Date:      Wed, 04 Dec 2002 16:46:32 -0800
From:      Lars Eggert <larse@ISI.EDU>
To:        Alfred Perlstein <alfred@FreeBSD.org>
Cc:        Kris Kennaway <kris@obsecurity.org>, current@FreeBSD.org, tanimura@FreeBSD.org
Subject:   Re: Lock order reversals in sys_pipe.c and kern_sig.c
Message-ID:  <3DEEA1E8.8000900@isi.edu>
In-Reply-To: <20021118190819.GK12906@rot13.obsecurity.org>
References:  <20021118190819.GK12906@rot13.obsecurity.org> <20021118193901.GA16066@elvis.mu.org> <3DEE8996.70602@isi.edu> <20021204231245.GH58155@elvis.mu.org>
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[-- Attachment #1 --]
Alfred Perlstein wrote:

> * Lars Eggert  [021204 15:04] wrote:
>
> >FYI, just got a similar one yesterday on an up-to-date -current:
> >
> >lock order reversal
> > 1st 0xc784d700 pipe mutex (pipe mutex) @ 
> /usr/src/sys/kern/sys_pipe.c:465
> > 2nd 0xc0513840 sigio lock (sigio lock) @ 
> /usr/src/sys/kern/kern_sig.c:2225
>
>
> Since no one has given me the traceback based on the patch I posted
> earlier I have ceased to care about the "problem".  If someone
> seriously cares they will run with my patch and post a backtrace.

Here's one:

lock order reversal
  1st 0xc795ea00 pipe mutex (pipe mutex) @ /usr/src/sys/kern/sys_pipe.c:465
  2nd 0xc0515340 sigio lock (sigio lock) @ /usr/src/sys/kern/kern_sig.c:2225
Debugger("witness_lock")
Stopped at      Debugger+0x5a:  xchgl   %ebx,in_Debugger.0

db> trace

Debugger(c0472495,c0515340,c04a8e51,c04a8e51,c04ab721) at Debugger+0x5a
witness_lock(c0515340,8,c04ab721,8b1,eb4d8be8) at witness_lock+0x142
_mtx_lock_flags(c0515340,0,c04ab721,8b1,c02f1531) at _mtx_lock_flags+0x63
pgsigio(c77afae8,17,0,1ad,0) at pgsigio+0x2d
pipe_read(c6ff8384,eb4d8c78,c6beb100,0,c6ac9e00) at pipe_read+0x2d4
dofileread(c6ac9e00,c6ff8384,3,bfbfe317,1) at dofileread+0xd7
read(c6ac9e00,eb4d8d10,c04c9811,407,c6bced50) at read+0x7b
syscall(2f,2f,bfbf002f,281dca2b,bfbfe330) at syscall+0x3c6
Xint0x80_syscall() at Xint0x80_syscall+0x1d
--- syscall (3, FreeBSD ELF32, read), eip = 0x280c5ff3, esp = 
0xbfbfe2fc, ebp = 0xbfbfe358 ---


-- 
Lars Eggert <larse@isi.edu>           USC Information Sciences Institute

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