Date: Tue, 11 Oct 2005 08:41:16 +0200 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: Brooks Davis <brooks@one-eyed-alien.net> Cc: Brooks Davis <brooks@FreeBSD.org>, FreeBSD Current <current@FreeBSD.org>, Andrew Thompson <thompsa@FreeBSD.org> Subject: Re: panic: ifc_free_unit: bit is already cleared Message-ID: <20051011064014.GA76710@garage.freebsd.pl> In-Reply-To: <20051005205515.GA30350@odin.ac.hmc.edu> References: <20051005024903.GA72743@heff.fud.org.nz> <20051005203639.GA20552@garage.freebsd.pl> <20051005205515.GA30350@odin.ac.hmc.edu>
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[-- Attachment #1 --] On Wed, Oct 05, 2005 at 01:55:15PM -0700, Brooks Davis wrote: +> On Wed, Oct 05, 2005 at 10:36:39PM +0200, Pawel Jakub Dawidek wrote: +> > On Wed, Oct 05, 2005 at 03:49:03PM +1300, Andrew Thompson wrote: +> > +> Hi, +> > +> +> > +> I have found a repeatable panic with network device cloning, unfortunatly I am +> > +> unable to dump on this box. This is sparc64 with a 2 day old current. +> > +> > The order is wrong in vlan_modevent(). +> > +> > if_clone_detach() is freeing ifc_units field, so ifc_free_unit() should not +> > be called after that. +> > +> > This patch should fix the problem: +> > +> > http://people.freebsd.org/~pjd/patches/if_vlan.c.patch +> +> Yes. This does introduce a race in that a new interface could +> be created between the vlan_clone_destroy loop and the call to +> if_clone_detach. It's going to be hard to trigger, but it probably +> should be fixed. Since cloning isn't performance critical, I think +> adding a dead flag to the clone structure and failing all attempts once +> the flag is set. I think it is a low-risk patch and the race isn't really critical. What do you guys think about going with this fix for 6.0? I'm all for better fix (the one thompsa@ is working on) going to HEAD and 6.1, but better fix - higher risk. So what's your opinion? Or maybe we will be able to create low-risk complete fix? -- Pawel Jakub Dawidek http://www.wheel.pl pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (FreeBSD) iD8DBQFDS16MForvXbEpPzQRAr+zAJ981doxmwrcbTehCgRemxn++v6U2wCbBYHs mewMhQgDm2FMoqCBK+jAvxU= =AED0 -----END PGP SIGNATURE-----
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