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Commit 51ebd318 authored by Nicolas Dichtel's avatar Nicolas Dichtel Committed by David S. Miller
Browse files

ipv6: add support of equal cost multipath (ECMP) 



Each nexthop is added like a single route in the routing table. All routes
that have the same metric/weight and destination but not the same gateway
are considering as ECMP routes. They are linked together, through a list called
rt6i_siblings.

ECMP routes can be added in one shot, with RTA_MULTIPATH attribute or one after
the other (in both case, the flag NLM_F_EXCL should not be set).

The patch is based on a previous work from
Luc Saillard <luc.saillard@6wind.com>.

Signed-off-by: default avatarNicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d94ce9b2

include/net/ip6_fib.h

+10 −0
Original line number Original line Diff line number Diff line
@@ -47,6 +47,8 @@ struct fib6_config { 
	unsigned long	fc_expires;

	unsigned long	fc_expires;

	struct nlattr	*fc_mx;

	struct nlattr	*fc_mx;

	int		fc_mx_len;

	int		fc_mx_len;

	int		fc_mp_len;

	struct nlattr	*fc_mp;





	struct nl_info	fc_nlinfo;

	struct nl_info	fc_nlinfo;

};

};
@@ -99,6 +101,14 @@ struct rt6_info { 




	struct in6_addr			rt6i_gateway;

	struct in6_addr			rt6i_gateway;





	/* Multipath routes:

	 * siblings is a list of rt6_info that have the the same metric/weight,

	 * destination, but not the same gateway. nsiblings is just a cache

	 * to speed up lookup.

	 */

	struct list_head		rt6i_siblings;

	unsigned int			rt6i_nsiblings;



	atomic_t			rt6i_ref;

	atomic_t			rt6i_ref;





	/* These are in a separate cache line. */

	/* These are in a separate cache line. */

net/ipv6/ip6_fib.c

+57 −0
Original line number Original line Diff line number Diff line
@@ -672,6 +672,8 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt, 
			    iter->rt6i_idev == rt->rt6i_idev &&

			    iter->rt6i_idev == rt->rt6i_idev &&

			    ipv6_addr_equal(&iter->rt6i_gateway,

			    ipv6_addr_equal(&iter->rt6i_gateway,

					    &rt->rt6i_gateway)) {

					    &rt->rt6i_gateway)) {

				if (rt->rt6i_nsiblings)

					rt->rt6i_nsiblings = 0;

				if (!(iter->rt6i_flags & RTF_EXPIRES))

				if (!(iter->rt6i_flags & RTF_EXPIRES))

					return -EEXIST;

					return -EEXIST;

				if (!(rt->rt6i_flags & RTF_EXPIRES))

				if (!(rt->rt6i_flags & RTF_EXPIRES))
@@ -680,6 +682,21 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt, 
					rt6_set_expires(iter, rt->dst.expires);

					rt6_set_expires(iter, rt->dst.expires);

				return -EEXIST;

				return -EEXIST;

			}

			}

			/* 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

			 * of siblings, and later we will add our route to the

			 * list.

			 * Only static routes (which don't have flag

			 * RTF_EXPIRES) are used for ECMPv6.

			 *

			 * To avoid long list, we only had siblings if the

			 * route have a gateway.

			 */

			if (rt->rt6i_flags & RTF_GATEWAY &&

			    !(rt->rt6i_flags & RTF_EXPIRES) &&

			    !(iter->rt6i_flags & RTF_EXPIRES))

				rt->rt6i_nsiblings++;

		}

		}





		if (iter->rt6i_metric > rt->rt6i_metric)

		if (iter->rt6i_metric > rt->rt6i_metric)
@@ -692,6 +709,35 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt, 
	if (ins == &fn->leaf)

	if (ins == &fn->leaf)

		fn->rr_ptr = NULL;

		fn->rr_ptr = NULL;





	/* Link this route to others same route. */

	if (rt->rt6i_nsiblings) {

		unsigned int rt6i_nsiblings;

		struct rt6_info *sibling, *temp_sibling;



		/* Find the first route that have the same metric */

		sibling = fn->leaf;

		while (sibling) {

			if (sibling->rt6i_metric == rt->rt6i_metric) {

				list_add_tail(&rt->rt6i_siblings,

					      &sibling->rt6i_siblings);

				break;

			}

			sibling = sibling->dst.rt6_next;

		}

		/* For each sibling in the list, increment the counter of

		 * siblings. BUG() if counters does not match, list of siblings

		 * is broken!

		 */

		rt6i_nsiblings = 0;

		list_for_each_entry_safe(sibling, temp_sibling,

					 &rt->rt6i_siblings, rt6i_siblings) {

			sibling->rt6i_nsiblings++;

			BUG_ON(sibling->rt6i_nsiblings != rt->rt6i_nsiblings);

			rt6i_nsiblings++;

		}

		BUG_ON(rt6i_nsiblings != rt->rt6i_nsiblings);

	}



	/*

	/*

	 *	insert node

	 *	insert node

	 */

	 */
@@ -1193,6 +1239,17 @@ static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp, 
	if (fn->rr_ptr == rt)

	if (fn->rr_ptr == rt)

		fn->rr_ptr = NULL;

		fn->rr_ptr = NULL;





	/* Remove this entry from other siblings */

	if (rt->rt6i_nsiblings) {

		struct rt6_info *sibling, *next_sibling;



		list_for_each_entry_safe(sibling, next_sibling,

					 &rt->rt6i_siblings, rt6i_siblings)

			sibling->rt6i_nsiblings--;

		rt->rt6i_nsiblings = 0;

		list_del_init(&rt->rt6i_siblings);

	}



	/* Adjust walkers */

	/* Adjust walkers */

	read_lock(&fib6_walker_lock);

	read_lock(&fib6_walker_lock);

	FOR_WALKERS(w) {

	FOR_WALKERS(w) {

net/ipv6/route.c

+133 −3
Original line number Original line Diff line number Diff line
@@ -57,6 +57,7 @@ 
#include <net/xfrm.h>

#include <net/xfrm.h>

#include <net/netevent.h>

#include <net/netevent.h>

#include <net/netlink.h>

#include <net/netlink.h>

#include <net/nexthop.h>





#include <asm/uaccess.h>

#include <asm/uaccess.h>
@@ -289,6 +290,8 @@ static inline struct rt6_info *ip6_dst_alloc(struct net *net, 
		memset(dst + 1, 0, sizeof(*rt) - sizeof(*dst));

		memset(dst + 1, 0, sizeof(*rt) - sizeof(*dst));

		rt6_init_peer(rt, table ? &table->tb6_peers : net->ipv6.peers);

		rt6_init_peer(rt, table ? &table->tb6_peers : net->ipv6.peers);

		rt->rt6i_genid = rt_genid(net);

		rt->rt6i_genid = rt_genid(net);

		INIT_LIST_HEAD(&rt->rt6i_siblings);

		rt->rt6i_nsiblings = 0;

	}

	}

	return rt;

	return rt;

}

}
@@ -385,6 +388,69 @@ static bool rt6_need_strict(const struct in6_addr *daddr) 
		(IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL | IPV6_ADDR_LOOPBACK);

		(IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL | IPV6_ADDR_LOOPBACK);

}

}





/* Multipath route selection:

 *   Hash based function using packet header and flowlabel.

 * Adapted from fib_info_hashfn()

 */

static int rt6_info_hash_nhsfn(unsigned int candidate_count,

			       const struct flowi6 *fl6)

{

	unsigned int val = fl6->flowi6_proto;



	val ^= fl6->daddr.s6_addr32[0];

	val ^= fl6->daddr.s6_addr32[1];

	val ^= fl6->daddr.s6_addr32[2];

	val ^= fl6->daddr.s6_addr32[3];



	val ^= fl6->saddr.s6_addr32[0];

	val ^= fl6->saddr.s6_addr32[1];

	val ^= fl6->saddr.s6_addr32[2];

	val ^= fl6->saddr.s6_addr32[3];



	/* Work only if this not encapsulated */

	switch (fl6->flowi6_proto) {

	case IPPROTO_UDP:

	case IPPROTO_TCP:

	case IPPROTO_SCTP:

		val ^= fl6->fl6_sport;

		val ^= fl6->fl6_dport;

		break;



	case IPPROTO_ICMPV6:

		val ^= fl6->fl6_icmp_type;

		val ^= fl6->fl6_icmp_code;

		break;

	}

	/* RFC6438 recommands to use flowlabel */

	val ^= fl6->flowlabel;



	/* Perhaps, we need to tune, this function? */

	val = val ^ (val >> 7) ^ (val >> 12);

	return val % candidate_count;

}



static struct rt6_info *rt6_multipath_select(struct rt6_info *match,

					     struct flowi6 *fl6)

{

	struct rt6_info *sibling, *next_sibling;

	int route_choosen;



	route_choosen = rt6_info_hash_nhsfn(match->rt6i_nsiblings + 1, fl6);

	/* Don't change the route, if route_choosen == 0

	 * (siblings does not include ourself)

	 */

	if (route_choosen)

		list_for_each_entry_safe(sibling, next_sibling,

				&match->rt6i_siblings, rt6i_siblings) {

			route_choosen--;

			if (route_choosen == 0) {

				match = sibling;

				break;

			}

		}

	return match;

}



/*

/*

 *	Route lookup. Any table->tb6_lock is implied.

 *	Route lookup. Any table->tb6_lock is implied.

 */

 */
@@ -702,6 +768,8 @@ static struct rt6_info *ip6_pol_route_lookup(struct net *net, 
restart:

restart:

	rt = fn->leaf;

	rt = fn->leaf;

	rt = rt6_device_match(net, rt, &fl6->saddr, fl6->flowi6_oif, flags);

	rt = rt6_device_match(net, rt, &fl6->saddr, fl6->flowi6_oif, flags);

	if (rt->rt6i_nsiblings && fl6->flowi6_oif == 0)

		rt = rt6_multipath_select(rt, fl6);

	BACKTRACK(net, &fl6->saddr);

	BACKTRACK(net, &fl6->saddr);

out:

out:

	dst_use(&rt->dst, jiffies);

	dst_use(&rt->dst, jiffies);
@@ -863,7 +931,8 @@ static struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table, 




restart:

restart:

	rt = rt6_select(fn, oif, strict | reachable);

	rt = rt6_select(fn, oif, strict | reachable);



	if (rt->rt6i_nsiblings && oif == 0)

		rt = rt6_multipath_select(rt, fl6);

	BACKTRACK(net, &fl6->saddr);

	BACKTRACK(net, &fl6->saddr);

	if (rt == net->ipv6.ip6_null_entry ||

	if (rt == net->ipv6.ip6_null_entry ||

	    rt->rt6i_flags & RTF_CACHE)

	    rt->rt6i_flags & RTF_CACHE)
@@ -2249,6 +2318,7 @@ static const struct nla_policy rtm_ipv6_policy[RTA_MAX+1] = { 
	[RTA_IIF]		= { .type = NLA_U32 },

	[RTA_IIF]		= { .type = NLA_U32 },

	[RTA_PRIORITY]          = { .type = NLA_U32 },

	[RTA_PRIORITY]          = { .type = NLA_U32 },

	[RTA_METRICS]           = { .type = NLA_NESTED },

	[RTA_METRICS]           = { .type = NLA_NESTED },

	[RTA_MULTIPATH]		= { .len = sizeof(struct rtnexthop) },

};

};





static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,

static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
@@ -2326,11 +2396,65 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh, 
	if (tb[RTA_TABLE])

	if (tb[RTA_TABLE])

		cfg->fc_table = nla_get_u32(tb[RTA_TABLE]);

		cfg->fc_table = nla_get_u32(tb[RTA_TABLE]);





	if (tb[RTA_MULTIPATH]) {

		cfg->fc_mp = nla_data(tb[RTA_MULTIPATH]);

		cfg->fc_mp_len = nla_len(tb[RTA_MULTIPATH]);

	}



	err = 0;

	err = 0;

errout:

errout:

	return err;

	return err;

}

}





static int ip6_route_multipath(struct fib6_config *cfg, int add)

{

	struct fib6_config r_cfg;

	struct rtnexthop *rtnh;

	int remaining;

	int attrlen;

	int err = 0, last_err = 0;



beginning:

	rtnh = (struct rtnexthop *)cfg->fc_mp;

	remaining = cfg->fc_mp_len;



	/* Parse a Multipath Entry */

	while (rtnh_ok(rtnh, remaining)) {

		memcpy(&r_cfg, cfg, sizeof(*cfg));

		if (rtnh->rtnh_ifindex)

			r_cfg.fc_ifindex = rtnh->rtnh_ifindex;



		attrlen = rtnh_attrlen(rtnh);

		if (attrlen > 0) {

			struct nlattr *nla, *attrs = rtnh_attrs(rtnh);



			nla = nla_find(attrs, attrlen, RTA_GATEWAY);

			if (nla) {

				nla_memcpy(&r_cfg.fc_gateway, nla, 16);

				r_cfg.fc_flags |= RTF_GATEWAY;

			}

		}

		err = add ? ip6_route_add(&r_cfg) : ip6_route_del(&r_cfg);

		if (err) {

			last_err = err;

			/* If we are trying to remove a route, do not stop the

			 * loop when ip6_route_del() fails (because next hop is

			 * already gone), we should try to remove all next hops.

			 */

			if (add) {

				/* If add fails, we should try to delete all

				 * next hops that have been already added.

				 */

				add = 0;

				goto beginning;

			}

		}

		rtnh = rtnh_next(rtnh, &remaining);

	}



	return last_err;

}



static int inet6_rtm_delroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)

static int inet6_rtm_delroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)

{

{

	struct fib6_config cfg;

	struct fib6_config cfg;
@@ -2340,6 +2464,9 @@ static int inet6_rtm_delroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *a 
	if (err < 0)

	if (err < 0)

		return err;

		return err;





	if (cfg.fc_mp)

		return ip6_route_multipath(&cfg, 0);

	else

		return ip6_route_del(&cfg);

		return ip6_route_del(&cfg);

}

}
@@ -2352,6 +2479,9 @@ static int inet6_rtm_newroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *a 
	if (err < 0)

	if (err < 0)

		return err;

		return err;





	if (cfg.fc_mp)

		return ip6_route_multipath(&cfg, 1);

	else

		return ip6_route_add(&cfg);

		return ip6_route_add(&cfg);

}

}