netdev - Re: [PATCH net-next] ipv6: do not merge differe type and protocol routes

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Date: Wed, 30 Aug 2023 17:48:20 +0800
From: Hangbin Liu <liuhangbin@...il.com>
To: netdev@...r.kernel.org
Cc: "David S . Miller" <davem@...emloft.net>,
	David Ahern <dsahern@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Ido Schimmel <idosch@...sch.org>,
	Thomas Haller <thaller@...hat.com>
Subject: Re: [PATCH net-next] ipv6: do not merge differe type and protocol
 routes

OH, Just saw net-next is closed. I will re-post it when open.

Hangbin
On Wed, Aug 30, 2023 at 05:38:01PM +0800, Hangbin Liu wrote:
> Sorry, Looks it failed when I cancel the git send-email. There is
> a typo in the subject. Should be "different" instead of "differe"...
> 
> I will fix this if there is an update needed.
> 
> Hangbin
> On Wed, Aug 30, 2023 at 02:16:22PM +0800, Hangbin Liu wrote:
> > Different with IPv4, IPv6 will auto merge the same metric routes into
> > multipath routes. But the different type and protocol routes are also
> > merged, which will lost user's configure info. e.g.
> > 
> > + ip route add local 2001:db8:103::/64 via 2001:db8:101::10 dev dummy1 table 100
> > + ip route append unicast 2001:db8:103::/64 via 2001:db8:101::10 dev dummy2 table 100
> > + ip -6 route show table 100
> > local 2001:db8:103::/64 metric 1024 pref medium
> >         nexthop via 2001:db8:101::10 dev dummy1 weight 1
> >         nexthop via 2001:db8:101::10 dev dummy2 weight 1
> > 
> > + ip route add 2001:db8:104::/64 via 2001:db8:101::10 dev dummy1 proto kernel table 200
> > + ip route append 2001:db8:104::/64 via 2001:db8:101::10 dev dummy2 proto bgp table 200
> > + ip -6 route show table 200
> > 2001:db8:104::/64 proto kernel metric 1024 pref medium
> >         nexthop via 2001:db8:101::10 dev dummy1 weight 1
> >         nexthop via 2001:db8:101::10 dev dummy2 weight 1
> > 
> > So let's skip counting the different type and protocol routes as siblings.
> > After update, the different type/protocol routes will not be merged.
> > 
> > + ip -6 route show table 100
> > local 2001:db8:103::/64 via 2001:db8:101::10 dev dummy1 metric 1024 pref medium
> > 2001:db8:103::/64 via 2001:db8:101::10 dev dummy2 metric 1024 pref medium
> > 
> > + ip -6 route show table 200
> > 2001:db8:104::/64 via 2001:db8:101::10 dev dummy1 proto kernel metric 1024 pref medium
> > 2001:db8:104::/64 via 2001:db8:101::10 dev dummy2 proto bgp metric 1024 pref medium
> > 
> > Reported-by: Thomas Haller <thaller@...hat.com>
> > Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2161994
> > Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
> > ---
> > All fib test passed:
> > Tests passed: 203
> > Tests failed:   0
> > ---
> >  net/ipv6/ip6_fib.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
> > index 28b01a068412..f60f5d14f034 100644
> > --- a/net/ipv6/ip6_fib.c
> > +++ b/net/ipv6/ip6_fib.c
> > @@ -1133,6 +1133,11 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
> >  							rt->fib6_pmtu);
> >  				return -EEXIST;
> >  			}
> > +
> > +			if (iter->fib6_type != rt->fib6_type ||
> > +			    iter->fib6_protocol != rt->fib6_protocol)
> > +				goto next_iter;
> > +
> >  			/* If we have the same destination and the same metric,
> >  			 * but not the same gateway, then the route we try to
> >  			 * add is sibling to this route, increment our counter
> > -- 
> > 2.41.0
> >