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Commit 398958ae authored by Ido Schimmel's avatar Ido Schimmel Committed by David S. Miller
Browse files

ipv6: Add support for non-equal-cost multipath 



The use of hash-threshold instead of modulo-N makes it trivial to add
support for non-equal-cost multipath.

Instead of dividing the multipath hash function's output space equally
between the nexthops, each nexthop is assigned a region size which is
proportional to its weight.

Signed-off-by: default avatarIdo Schimmel <idosch@mellanox.com>
Acked-by: default avatarDavid Ahern <dsahern@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3d709f69

include/net/ip6_fib.h

+1 −0
Original line number Diff line number Diff line
@@ -171,6 +171,7 @@ struct rt6_info { 
	u32				rt6i_metric;

	u32				rt6i_pmtu;

	/* more non-fragment space at head required */

	int				rt6i_nh_weight;

	unsigned short			rt6i_nfheader_len;

	u8				rt6i_protocol;

	u8				exception_bucket_flushed:1,

net/ipv6/route.c

+7 −4
Original line number Diff line number Diff line
@@ -2594,6 +2594,7 @@ static struct rt6_info *ip6_route_info_create(struct fib6_config *cfg, 
#endif



	rt->rt6i_metric = cfg->fc_metric;

	rt->rt6i_nh_weight = 1;



	/* We cannot add true routes via loopback here,

	   they would result in kernel looping; promote them to reject routes
@@ -3507,11 +3508,11 @@ static int rt6_multipath_total_weight(const struct rt6_info *rt) 
	int total = 0;



	if (!rt6_is_dead(rt))

		total++;

		total += rt->rt6i_nh_weight;



	list_for_each_entry(iter, &rt->rt6i_siblings, rt6i_siblings) {

		if (!rt6_is_dead(iter))

			total++;

			total += iter->rt6i_nh_weight;

	}



	return total;
@@ -3522,7 +3523,7 @@ static void rt6_upper_bound_set(struct rt6_info *rt, int *weight, int total) 
	int upper_bound = -1;



	if (!rt6_is_dead(rt)) {

		(*weight)++;

		*weight += rt->rt6i_nh_weight;

		upper_bound = DIV_ROUND_CLOSEST_ULL((u64) (*weight) << 31,

						    total) - 1;

	}
@@ -4024,6 +4025,8 @@ static int ip6_route_multipath_add(struct fib6_config *cfg, 
			goto cleanup;

		}



		rt->rt6i_nh_weight = rtnh->rtnh_hops + 1;



		err = ip6_route_info_append(&rt6_nh_list, rt, &r_cfg);

		if (err) {

			dst_release_immediate(&rt->dst);
@@ -4246,7 +4249,7 @@ static int rt6_add_nexthop(struct sk_buff *skb, struct rt6_info *rt) 
	if (!rtnh)

		goto nla_put_failure;



	rtnh->rtnh_hops = 0;

	rtnh->rtnh_hops = rt->rt6i_nh_weight - 1;

	rtnh->rtnh_ifindex = rt->dst.dev ? rt->dst.dev->ifindex : 0;



	if (rt6_nexthop_info(skb, rt, &flags, true) < 0)