Commit 8448f91f authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'ipv6-Add-support-for-non-equal-cost-multipath' 



Ido Schimmel says:

====================
ipv6: Add support for non-equal-cost multipath

This set aims to add support for IPv6 non-equal-cost multipath routes.
The first three patches convert multipath selection to use the
hash-threshold method (RFC 2992) instead of modulo-N. The same method is
employed by the IPv4 routing code since commit 0e884c78 ("ipv4: L3
hash-based multipath").

Unlike modulo-N, with hash-threshold only the flows near the region
boundaries are affected when a nexthop is added or removed. In addition,
it allows us to easily add support for non-equal-cost multipath in the
last patch by sizing the different regions according to the provided
weights.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents e2b3b35e 398958ae

include/net/ip6_fib.h

+2 −0
Original line number Diff line number Diff line
@@ -149,6 +149,7 @@ struct rt6_info { 
	 */

	struct list_head		rt6i_siblings;

	unsigned int			rt6i_nsiblings;

	atomic_t			rt6i_nh_upper_bound;



	atomic_t			rt6i_ref;
@@ -170,6 +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,

include/net/ip6_route.h

+7 −0
Original line number Diff line number Diff line
@@ -66,6 +66,12 @@ static inline bool rt6_need_strict(const struct in6_addr *daddr) 
		(IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL | IPV6_ADDR_LOOPBACK);

}



static inline bool rt6_qualify_for_ecmp(const struct rt6_info *rt)

{

	return (rt->rt6i_flags & (RTF_GATEWAY|RTF_ADDRCONF|RTF_DYNAMIC)) ==

	       RTF_GATEWAY;

}



void ip6_route_input(struct sk_buff *skb);

struct dst_entry *ip6_route_input_lookup(struct net *net,

					 struct net_device *dev,
@@ -171,6 +177,7 @@ void rt6_clean_tohost(struct net *net, struct in6_addr *gateway); 
void rt6_sync_up(struct net_device *dev, unsigned int nh_flags);

void rt6_disable_ip(struct net_device *dev, unsigned long event);

void rt6_sync_down_dev(struct net_device *dev, unsigned long event);

void rt6_multipath_rebalance(struct rt6_info *rt);



static inline const struct rt6_info *skb_rt6_info(const struct sk_buff *skb)

{

net/ipv6/ip6_fib.c

+2 −6
Original line number Diff line number Diff line
@@ -796,12 +796,6 @@ insert_above: 
	return ln;

}



static bool rt6_qualify_for_ecmp(struct rt6_info *rt)

{

	return (rt->rt6i_flags & (RTF_GATEWAY|RTF_ADDRCONF|RTF_DYNAMIC)) ==

	       RTF_GATEWAY;

}



static void fib6_copy_metrics(u32 *mp, const struct mx6_config *mxc)

{

	int i;
@@ -991,6 +985,7 @@ next_iter: 
			rt6i_nsiblings++;

		}

		BUG_ON(rt6i_nsiblings != rt->rt6i_nsiblings);

		rt6_multipath_rebalance(temp_sibling);

	}



	/*
@@ -1672,6 +1667,7 @@ static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn, 
			sibling->rt6i_nsiblings--;

		rt->rt6i_nsiblings = 0;

		list_del_init(&rt->rt6i_siblings);

		rt6_multipath_rebalance(next_sibling);

	}



	/* Adjust walkers */

net/ipv6/route.c

+115 −26
Original line number Diff line number Diff line
@@ -455,7 +455,6 @@ static struct rt6_info *rt6_multipath_select(struct rt6_info *match, 
					     int strict)

{

	struct rt6_info *sibling, *next_sibling;

	int route_choosen;



	/* We might have already computed the hash for ICMPv6 errors. In such

	 * case it will always be non-zero. Otherwise now is the time to do it.
@@ -463,28 +462,19 @@ static struct rt6_info *rt6_multipath_select(struct rt6_info *match, 
	if (!fl6->mp_hash)

		fl6->mp_hash = rt6_multipath_hash(fl6, NULL);



	route_choosen = fl6->mp_hash % (match->rt6i_nsiblings + 1);

	/* 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) {

				struct inet6_dev *idev = sibling->rt6i_idev;

	if (fl6->mp_hash <= atomic_read(&match->rt6i_nh_upper_bound))

		return match;



				if (sibling->rt6i_nh_flags & RTNH_F_DEAD)

					break;

				if (sibling->rt6i_nh_flags & RTNH_F_LINKDOWN &&

				    idev->cnf.ignore_routes_with_linkdown)

					break;

	list_for_each_entry_safe(sibling, next_sibling, &match->rt6i_siblings,

				 rt6i_siblings) {

		if (fl6->mp_hash > atomic_read(&sibling->rt6i_nh_upper_bound))

			continue;

		if (rt6_score_route(sibling, oif, strict) < 0)

			break;

		match = sibling;

		break;

	}

		}



	return match;

}
@@ -1833,10 +1823,10 @@ u32 rt6_multipath_hash(const struct flowi6 *fl6, const struct sk_buff *skb) 


	if (skb) {

		ip6_multipath_l3_keys(skb, &hash_keys);

		return flow_hash_from_keys(&hash_keys);

		return flow_hash_from_keys(&hash_keys) >> 1;

	}



	return get_hash_from_flowi6(fl6);

	return get_hash_from_flowi6(fl6) >> 1;

}



void ip6_route_input(struct sk_buff *skb)
@@ -2604,6 +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
@@ -3481,6 +3472,99 @@ struct arg_netdev_event { 
	};

};



static struct rt6_info *rt6_multipath_first_sibling(const struct rt6_info *rt)

{

	struct rt6_info *iter;

	struct fib6_node *fn;



	fn = rcu_dereference_protected(rt->rt6i_node,

			lockdep_is_held(&rt->rt6i_table->tb6_lock));

	iter = rcu_dereference_protected(fn->leaf,

			lockdep_is_held(&rt->rt6i_table->tb6_lock));

	while (iter) {

		if (iter->rt6i_metric == rt->rt6i_metric &&

		    rt6_qualify_for_ecmp(iter))

			return iter;

		iter = rcu_dereference_protected(iter->rt6_next,

				lockdep_is_held(&rt->rt6i_table->tb6_lock));

	}



	return NULL;

}



static bool rt6_is_dead(const struct rt6_info *rt)

{

	if (rt->rt6i_nh_flags & RTNH_F_DEAD ||

	    (rt->rt6i_nh_flags & RTNH_F_LINKDOWN &&

	     rt->rt6i_idev->cnf.ignore_routes_with_linkdown))

		return true;



	return false;

}



static int rt6_multipath_total_weight(const struct rt6_info *rt)

{

	struct rt6_info *iter;

	int total = 0;



	if (!rt6_is_dead(rt))

		total += rt->rt6i_nh_weight;



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

		if (!rt6_is_dead(iter))

			total += iter->rt6i_nh_weight;

	}



	return total;

}



static void rt6_upper_bound_set(struct rt6_info *rt, int *weight, int total)

{

	int upper_bound = -1;



	if (!rt6_is_dead(rt)) {

		*weight += rt->rt6i_nh_weight;

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

						    total) - 1;

	}

	atomic_set(&rt->rt6i_nh_upper_bound, upper_bound);

}



static void rt6_multipath_upper_bound_set(struct rt6_info *rt, int total)

{

	struct rt6_info *iter;

	int weight = 0;



	rt6_upper_bound_set(rt, &weight, total);



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

		rt6_upper_bound_set(iter, &weight, total);

}



void rt6_multipath_rebalance(struct rt6_info *rt)

{

	struct rt6_info *first;

	int total;



	/* In case the entire multipath route was marked for flushing,

	 * then there is no need to rebalance upon the removal of every

	 * sibling route.

	 */

	if (!rt->rt6i_nsiblings || rt->should_flush)

		return;



	/* During lookup routes are evaluated in order, so we need to

	 * make sure upper bounds are assigned from the first sibling

	 * onwards.

	 */

	first = rt6_multipath_first_sibling(rt);

	if (WARN_ON_ONCE(!first))

		return;



	total = rt6_multipath_total_weight(first);

	rt6_multipath_upper_bound_set(first, total);

}



static int fib6_ifup(struct rt6_info *rt, void *p_arg)

{

	const struct arg_netdev_event *arg = p_arg;
@@ -3489,6 +3573,7 @@ static int fib6_ifup(struct rt6_info *rt, void *p_arg) 
	if (rt != net->ipv6.ip6_null_entry && rt->dst.dev == arg->dev) {

		rt->rt6i_nh_flags &= ~arg->nh_flags;

		fib6_update_sernum_upto_root(dev_net(rt->dst.dev), rt);

		rt6_multipath_rebalance(rt);

	}



	return 0;
@@ -3588,6 +3673,7 @@ static int fib6_ifdown(struct rt6_info *rt, void *p_arg) 
			rt6_multipath_nh_flags_set(rt, dev, RTNH_F_DEAD |

						   RTNH_F_LINKDOWN);

			fib6_update_sernum(rt);

			rt6_multipath_rebalance(rt);

		}

		return -2;

	case NETDEV_CHANGE:
@@ -3595,6 +3681,7 @@ static int fib6_ifdown(struct rt6_info *rt, void *p_arg) 
		    rt->rt6i_flags & (RTF_LOCAL | RTF_ANYCAST))

			break;

		rt->rt6i_nh_flags |= RTNH_F_LINKDOWN;

		rt6_multipath_rebalance(rt);

		break;

	}
@@ -3938,6 +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);
@@ -4160,7 +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)

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