Re: [PATCH net v3 2/2] ipv6: fix ECMP route replacement

[Nicolas Dichtel]

Le 18/05/2015 20:54, Michal Kubecek a Ãcrit :
> When replacing an IPv6 multipath route with "ip route replace", i.e.
> NLM_F_CREATE | NLM_F_REPLACE, fib6_add_rt2node() replaces only first
> matching route without fixing its siblings, resulting in corrupted
> siblings linked list; removing one of the siblings can then end in an
> infinite loop.
>
> IPv6 ECMP implementation is a bit different from IPv4 so that route
> replacement cannot work in exactly the same way. This should be a
> reasonable approximation:
>
> 1. If the new route is ECMP-able and there is a matching ECMP-able one
> already, replace it and all its siblings (if any).
>
> 2. If the new route is ECMP-able and no matching ECMP-able route exists,
> replace first matching non-ECMP-able (if any) or just add the new one.
>
> 3. If the new route is not ECMP-able, replace first matching
> non-ECMP-able route (if any) or add the new route.
>
> We also need to remove the NLM_F_REPLACE flag after replacing old
> route(s) by first nexthop of an ECMP route so that each subsequent
> nexthop does not replace previous one.
>
> Fixes: 51ebd3181572 ("ipv6: add support of equal cost multipath (ECMP)")
> Signed-off-by: Michal Kubecek <mkubecek@xxxxxxx>
LGTM.
Acked-by: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>
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