Date: Sat, 16 Aug 2003 01:13:30 -0700 From: Kris Kennaway <kris@obsecurity.org> To: Poul-Henning Kamp <phk@phk.freebsd.dk> Cc: Kris Kennaway <kris@obsecurity.org> Subject: Re: LOR with filedesc structure and Giant Message-ID: <20030816081330.GA73680@rot13.obsecurity.org> In-Reply-To: <18472.1061017947@critter.freebsd.dk> References: <Pine.NEB.3.96L.1030815225914.97011A-100000@fledge.watson.org> <18472.1061017947@critter.freebsd.dk>
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--AhhlLboLdkugWU4S Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Aug 16, 2003 at 09:12:27AM +0200, Poul-Henning Kamp wrote: > In message <Pine.NEB.3.96L.1030815225914.97011A-100000@fledge.watson.org>= , Robe > rt Watson writes: > > > >On Fri, 15 Aug 2003, Kris Kennaway wrote: > > > >> The problem seems to be due to select() being called on the /dev/null > >> device, and it is holding the filedesc lock when it reaches > >> PICKUP_GIANT() in spec_poll. > > > >Yeah, this is pretty much the same issue you've been bumping into for a > >bit -- we hold filedesc lock over select(), which means every object we > >poll can't grab a lock that either comes before the file descriptor lock= in > >the lock order, or that might sleep. >=20 > Doesn't this effectively doom any attempt at getting rid af Giant > from below ? It seems like the locking strategy is wrong (see other LORs in select() and poll()). Alfred said he had fixed it, but it was backed out: http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/kern/kern_descrip.c?rev=3D1.1= 91&content-type=3Dtext/x-cvsweb-markup As I seem to recall, his strategy of fixing the problem itself caused other problems, though (which was why it was backed out). Kris --AhhlLboLdkugWU4S Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.2 (FreeBSD) iD8DBQE/PeeqWry0BWjoQKURApoOAJ0WKpKCI088jOfv/uuDsV9FSg7SHQCdH/gG AAYLEwxovhOXrRkV3m5nPy8= =wWpw -----END PGP SIGNATURE----- --AhhlLboLdkugWU4S--
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