From 51ebd3181572af8d5076808dab2682d800f6da5d Mon Sep 17 00:00:00 2001 From: Nicolas Dichtel Date: Mon, 22 Oct 2012 03:42:09 +0000 Subject: 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 . Signed-off-by: Nicolas Dichtel Signed-off-by: David S. Miller --- include/net/ip6_fib.h | 10 ++++ net/ipv6/ip6_fib.c | 57 +++++++++++++++++++++ net/ipv6/route.c | 136 ++++++++++++++++++++++++++++++++++++++++++++++++-- 3 files changed, 200 insertions(+), 3 deletions(-) diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h index 8a2a203eb15..20210d79e36 100644 --- a/include/net/ip6_fib.h +++ b/include/net/ip6_fib.h @@ -47,6 +47,8 @@ struct fib6_config { unsigned long fc_expires; struct nlattr *fc_mx; int fc_mx_len; + int fc_mp_len; + struct nlattr *fc_mp; struct nl_info fc_nlinfo; }; @@ -99,6 +101,14 @@ struct rt6_info { 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; /* These are in a separate cache line. */ diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index 24995a93ef8..710cafd2e1a 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -672,6 +672,8 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt, iter->rt6i_idev == rt->rt6i_idev && ipv6_addr_equal(&iter->rt6i_gateway, &rt->rt6i_gateway)) { + if (rt->rt6i_nsiblings) + rt->rt6i_nsiblings = 0; if (!(iter->rt6i_flags & RTF_EXPIRES)) return -EEXIST; 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); 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) @@ -692,6 +709,35 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt, if (ins == &fn->leaf) 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 */ @@ -1193,6 +1239,17 @@ static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp, if (fn->rr_ptr == rt) 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 */ read_lock(&fib6_walker_lock); FOR_WALKERS(w) { diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 7c7e963260e..126da562d3e 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -57,6 +57,7 @@ #include #include #include +#include #include @@ -289,6 +290,8 @@ static inline struct rt6_info *ip6_dst_alloc(struct net *net, memset(dst + 1, 0, sizeof(*rt) - sizeof(*dst)); rt6_init_peer(rt, table ? &table->tb6_peers : net->ipv6.peers); rt->rt6i_genid = rt_genid(net); + INIT_LIST_HEAD(&rt->rt6i_siblings); + rt->rt6i_nsiblings = 0; } 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); } +/* 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. */ @@ -702,6 +768,8 @@ static struct rt6_info *ip6_pol_route_lookup(struct net *net, restart: rt = fn->leaf; 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); out: dst_use(&rt->dst, jiffies); @@ -863,7 +931,8 @@ restart_2: restart: rt = rt6_select(fn, oif, strict | reachable); - + if (rt->rt6i_nsiblings && oif == 0) + rt = rt6_multipath_select(rt, fl6); BACKTRACK(net, &fl6->saddr); if (rt == net->ipv6.ip6_null_entry || 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_PRIORITY] = { .type = NLA_U32 }, [RTA_METRICS] = { .type = NLA_NESTED }, + [RTA_MULTIPATH] = { .len = sizeof(struct rtnexthop) }, }; 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]) 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; errout: 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) { struct fib6_config cfg; @@ -2340,7 +2464,10 @@ static int inet6_rtm_delroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *a if (err < 0) return err; - return ip6_route_del(&cfg); + if (cfg.fc_mp) + return ip6_route_multipath(&cfg, 0); + else + return ip6_route_del(&cfg); } static int inet6_rtm_newroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg) @@ -2352,7 +2479,10 @@ static int inet6_rtm_newroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *a if (err < 0) return err; - return ip6_route_add(&cfg); + if (cfg.fc_mp) + return ip6_route_multipath(&cfg, 1); + else + return ip6_route_add(&cfg); } static inline size_t rt6_nlmsg_size(void) -- cgit v1.2.3