Re: Lock order reversals in sys_pipe.c and kern_sig.c

[Lars Eggert]

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 <[EMAIL PROTECTED]> USC Information Sciences Institute

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