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Date: Fri, 16 Jan 2004 18:24:24 -0500 (EST)
From: Robert Watson <rwatson@FreeBSD.org>
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To: Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?= <des@des.no>
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cc: "Brian F. Feldman" <green@FreeBSD.org>
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Subject: Re: cvs commit: src/sys/kern kern_descrip.c
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On Fri, 16 Jan 2004, Dag-Erling Sm=F8rgrav wrote:

> "Brian F. Feldman" <green@FreeBSD.org> writes:
> > I don't see a reason "newfdp" needs to be locked, since it is not
> > referenced by anything yet.  If "fdp" alone is locked, that is
> > sufficient to ensure they will both be consistent.
>=20
> It needs to be locked because it is passed to functions which assert
> that it is locked.=20

It sounds like this is an API problem, and is probably what we should fix.=
=20
I've found WITNESS an invaluable debugging tool for locking, and when
programming on systems without it, it's a very painful experience (i.e.,
debugging lock orders on Darwin).  You've also pointed out that the extra
locking work being done is actually unnecessary, so maybe we just need an
_unlocked() version of the API, or changes elsewhere?=20

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org      Senior Research Scientist, McAfee Research