Date: Tue, 23 Dec 2003 12:26:45 +0100 From: Simon Heath <heath@cng.fr> To: Poul-Henning Kamp <phk@phk.freebsd.dk> Cc: freebsd-current@freebsd.org Subject: Re: cd taste crash followup Message-ID: <20031223112645.GA14443@madiran.cng.fr> In-Reply-To: <43106.1072177560@critter.freebsd.dk> References: <20031223105208.GA8531@madiran.cng.fr> <43106.1072177560@critter.freebsd.dk>
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On Tue, Dec 23, 2003 at 12:06:00PM +0100, Poul-Henning Kamp wrote:
> In message <20031223105208.GA8531@madiran.cng.fr>, Simon Heath writes:
>
> >The calls come from g_orphan_register which calls g_dev_orphan() on each
> >element from pp->consumers, which in turn calls g_detach() which calls
> >g_destroy_provider(). g_orphan_register() then calls g_destroy_provider()
> >directly with pp (because G_PF_WITHER is set), but pp has already been
> >passed to g_destroy_provider() in the previous loop, so we end up with the
> >attempt to remove the devstat twice. As to why pp appears as a provider in
> >pp->consumers I have no idea, but I hope this makes some sense to people who
> >understand GEOM.
>
> Sigh, I know the per provider wither flag sounded too easy...
>
> Can you try this patch ?
>
> Index: geom_event.c
> ===================================================================
> RCS file: /home/ncvs/src/sys/geom/geom_event.c,v
> retrieving revision 1.44
> diff -u -r1.44 geom_event.c
> --- geom_event.c 7 Dec 2003 10:04:43 -0000 1.44
> +++ geom_event.c 23 Dec 2003 11:04:58 -0000
> @@ -126,10 +126,14 @@
> g_orphan_register(struct g_provider *pp)
> {
> struct g_consumer *cp, *cp2;
> + int wf;
>
> g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
> g_topology_assert();
>
> + wf = pp->flags & G_PF_WITHER;
> + pp->flags &= ~G_PF_WITHER;
> +
> /*
> * Tell all consumers the bad news.
> * Don't be surprised if they self-destruct.
> @@ -143,8 +147,10 @@
> cp->geom->orphan(cp);
> cp = cp2;
> }
> - if (LIST_EMPTY(&pp->consumers) && (pp->flags & G_PF_WITHER))
> + if (LIST_EMPTY(&pp->consumers) && wf)
> g_destroy_provider(pp);
> + else
> + pp->flags |= wf;
> #ifdef notyet
> cp = LIST_FIRST(&pp->consumers);
> if (cp != NULL)
>
That works fine for me - I can't reproduce the crash with this patch.
Thanks,
Simon
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