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Date: Sat, 18 Aug 2007 17:00:28 +0200
From: Pawel Jakub Dawidek <pjd@FreeBSD.org>
To: Alfred Perlstein <alfred@freebsd.org>
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Cc: freebsd-arch@FreeBSD.org
Subject: Re: Lockless uidinfo.
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On Sat, Aug 18, 2007 at 07:23:37AM -0700, Alfred Perlstein wrote:
> * Pawel Jakub Dawidek <pjd@FreeBSD.org> [070818 05:31] wrote:
> > Hi.
> >=20
> > The patch below remove per-uidinfo locks:
> >=20
> > 	http://people.freebsd.org/~pjd/patches/uidinfo_lockless.patch
>=20
> In uifree() is it ok to manually check the refcount for 0?
>=20
> I'm gussing the hashmtx is used as a barrier?

Yes, to lookup uidinfo you need to hold uihashtbl_mtx mutex, so once you
hold it and ui_ref is 0, noone will be able to reference it, because it
has to wait to look it up.

--=20
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd@FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!

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