[PATCH net-next v2 3/5] ipv6: Use multipath hash from flow info if available

[Jakub Sitnicki <jkbs@redhat.com>]

Allow our callers to influence the choice of ECMP link by honoring the
hash passed together with the flow info. This will allow for special
treatment of ICMP errors which we would like to route over the same link
as the IP datagram that triggered the error.

Signed-off-by: Jakub Sitnicki <jkbs@redhat.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
---
 net/ipv6/route.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 0514b35..1184c2b 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -430,9 +430,11 @@ static struct rt6_info *rt6_multipath_select(struct rt6_info *match,
 					     int strict)
 {
 	struct rt6_info *sibling, *next_sibling;
+	unsigned int hash;
 	int route_choosen;
 
-	route_choosen = get_hash_from_flowi6(fl6) % (match->rt6i_nsiblings + 1);
+	hash = fl6->mp_hash ? : get_hash_from_flowi6(fl6);
+	route_choosen = hash % (match->rt6i_nsiblings + 1);
 	/* Don't change the route, if route_choosen == 0
 	 * (siblings does not include ourself)
 	 */
-- 
2.7.4