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Date:      Mon, 18 Nov 2002 15:43:10 -0500 (EST)
From:      John Baldwin <jhb@FreeBSD.org>
To:        Alfred Perlstein <alfred@FreeBSD.ORG>
Cc:        tanimura@FreeBSD.ORG, current@FreeBSD.ORG, Kris Kennaway <kris@obsecurity.org>
Subject:   Re: Lock order reversals in sys_pipe.c and kern_sig.c
Message-ID:  <XFMail.20021118154310.jhb@FreeBSD.org>
In-Reply-To: <20021118201808.GB16066@elvis.mu.org>

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On 18-Nov-2002 Alfred Perlstein wrote:
> * Kris Kennaway <kris@obsecurity.org> [021118 12:01] wrote:
>> On Mon, Nov 18, 2002 at 11:39:01AM -0800, Alfred Perlstein wrote:
>> 
>> > Well now they are, I will investigate as time permits.
>> 
>> Thanks.
>> 
>> > I'm still in a holding pattern about adding more debugging info to
>> > lockd now that we're in release candidate mode.  I may ask for a
>> > branch to be done, but i'm not sure yet.
>> 
>> Feel free to give me non-committed patches to test :-)
> 
> GRR, witless always gives me the locations of the correct lock
> order, never the locations of the incorrect ones, so here, try this
> and give me a backtrace, it should nail you with extreme prejudice
> when you get what i think is the wrong order:

This is why there is a static lock-order list that you can add to.
For example:

Index: subr_witness.c
===================================================================
RCS file: /usr/cvs/src/sys/kern/subr_witness.c,v
retrieving revision 1.130
diff -u -r1.130 subr_witness.c
--- subr_witness.c      11 Nov 2002 16:36:20 -0000      1.130
+++ subr_witness.c      18 Nov 2002 20:42:35 -0000
@@ -205,6 +205,9 @@
        { "uidinfo hash", &lock_class_mtx_sleep },
        { "uidinfo struct", &lock_class_mtx_sleep },
        { NULL, NULL },
+       { "sigio lock", &lock_class_mtx_sleep },
+       { "pipe mutex", &lock_class_mtx_sleep },
+       { NULL, NULL },
        /*
         * spin locks
         */


-- 

John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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