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Date: Wed, 8 Jan 2014 09:05:28 +0100
From: Hannes Frederic Sowa <hannes@...essinduktion.org>
To: Gao feng <gaofeng@...fujitsu.com>
Cc: chenweilong <chenweilong@...wei.com>,
David Miller <davem@...emloft.net>, kumaran.4353@...il.com,
netdev@...r.kernel.org
Subject: Re: [PATCH] ipv6: don't call addrconf_dst_alloc again when enable lo
On Wed, Jan 08, 2014 at 03:50:09PM +0800, Gao feng wrote:
> On 01/03/2014 02:53 PM, Hannes Frederic Sowa wrote:
> > On Thu, Jan 02, 2014 at 05:33:15PM +0800, chenweilong wrote:
> >> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> >> index 62d1799..d2f8c0a 100644
> >> --- a/net/ipv6/addrconf.c
> >> +++ b/net/ipv6/addrconf.c
> >> @@ -2422,8 +2422,9 @@ static void init_loopback(struct net_device *dev)
> >> if (sp_ifa->flags & (IFA_F_DADFAILED | IFA_F_TENTATIVE))
> >> continue;
> >>
> >> - if (sp_ifa->rt)
> >> - continue;
> >> + if (sp_ifa->rt && sp_ifa->rt->dst.dev == dev) {
> >> + ip6_del_rt(sp_ifa->rt);
> >> + }
> >>
> >> sp_rt = addrconf_dst_alloc(idev, &sp_ifa->addr, 0);
> >>
> >
> > Maybe this change would not be that bad after all, as those ifa attached dsts
> > are already dead and queued up for gc and should not get inserted back.
>
> I like this idea, maybe the below patch is better. we only need to delete this
> route when it has been added to garbage list.
>
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index 1a341f7..4dca886 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -2610,8 +2610,16 @@ static void init_loopback(struct net_device *dev)
> if (sp_ifa->flags & (IFA_F_DADFAILED | IFA_F_TENTATIVE))
> continue;
>
> - if (sp_ifa->rt)
> - continue;
> + if (sp_ifa->rt) {
> + /* This dst has been added to garbage list when
> + * lo device down, delete this obsolete dst and
> + * reallocate new router for ifa. */
> + if (sp_ifa->rt->dst.obsolete > 0) {
> + ip6_del_rt(sp_ifa->rt);
> + sp_ifa->rt = NULL;
> + } else
> + continue;
> + }
>
> sp_rt = addrconf_dst_alloc(idev, &sp_ifa->addr, false);
It looks like it can work but I don't know if we should just fix this the
clean way (see below).
> > I'll try to just disable routes without removing them at all when we set an
> > interface to down at the weekend.
> >
>
> How do you decide which route should be disabled? use rt6_flags? I don't know
> if your way will cause miscarriage.
What I did so far is that I added a new function next to rt6_ifdown that
only gets called if interface gets shutdown but not unregistered (from
addrconf_ifdown).
fib6_clean_all then iterates over the whole routing table with a new predicate
function which checks in the same way like fib6_ifdown, if it is a matching route
(the interfaces match up) and if so, toggles a new "DEAD" flag in rt6i_flags.
When bringing up the interface I distinguish between up and register and just
clear this death flag from the routes on bringing it up.
fib lookup code then does not honour those routes.
I had no time to test this thoroughly at the weekend and still have some code
paths were I am unsure. Do you see any problems with this so far? We could
then delete the special cases on loopback interface init.
Thanks,
Hannes
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