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ipv4: L3 hash-based multipath
Replaces the per-packet multipath with a hash-based multipath using source and destination address. Signed-off-by: Peter Nørlund <pch@ordbogen.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Peter Nørlund
David S. Miller
parent
2472186f58
commit
0e884c78ee
3 changed files with 98 additions and 72 deletions
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@ -79,7 +79,7 @@ struct fib_nh {
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unsigned char nh_scope;
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#ifdef CONFIG_IP_ROUTE_MULTIPATH
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int nh_weight;
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int nh_power;
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atomic_t nh_upper_bound;
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#endif
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#ifdef CONFIG_IP_ROUTE_CLASSID
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__u32 nh_tclassid;
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@ -118,7 +118,7 @@ struct fib_info {
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#define fib_advmss fib_metrics[RTAX_ADVMSS-1]
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int fib_nhs;
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#ifdef CONFIG_IP_ROUTE_MULTIPATH
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int fib_power;
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int fib_weight;
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#endif
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struct rcu_head rcu;
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struct fib_nh fib_nh[0];
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@ -320,7 +320,15 @@ int ip_fib_check_default(__be32 gw, struct net_device *dev);
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int fib_sync_down_dev(struct net_device *dev, unsigned long event);
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int fib_sync_down_addr(struct net *net, __be32 local);
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int fib_sync_up(struct net_device *dev, unsigned int nh_flags);
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void fib_select_multipath(struct fib_result *res);
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extern u32 fib_multipath_secret __read_mostly;
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static inline int fib_multipath_hash(__be32 saddr, __be32 daddr)
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{
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return jhash_2words(saddr, daddr, fib_multipath_secret) >> 1;
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}
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void fib_select_multipath(struct fib_result *res, int hash);
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/* Exported by fib_trie.c */
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void fib_trie_init(void);
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@ -57,8 +57,7 @@ static unsigned int fib_info_cnt;
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static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
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#ifdef CONFIG_IP_ROUTE_MULTIPATH
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static DEFINE_SPINLOCK(fib_multipath_lock);
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u32 fib_multipath_secret __read_mostly;
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#define for_nexthops(fi) { \
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int nhsel; const struct fib_nh *nh; \
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@ -532,7 +531,67 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
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return ret;
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}
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#endif
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static void fib_rebalance(struct fib_info *fi)
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{
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int total;
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int w;
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struct in_device *in_dev;
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if (fi->fib_nhs < 2)
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return;
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total = 0;
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for_nexthops(fi) {
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if (nh->nh_flags & RTNH_F_DEAD)
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continue;
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in_dev = __in_dev_get_rcu(nh->nh_dev);
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if (in_dev &&
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IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
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nh->nh_flags & RTNH_F_LINKDOWN)
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continue;
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total += nh->nh_weight;
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} endfor_nexthops(fi);
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w = 0;
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change_nexthops(fi) {
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int upper_bound;
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in_dev = __in_dev_get_rcu(nexthop_nh->nh_dev);
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if (nexthop_nh->nh_flags & RTNH_F_DEAD) {
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upper_bound = -1;
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} else if (in_dev &&
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IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
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nexthop_nh->nh_flags & RTNH_F_LINKDOWN) {
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upper_bound = -1;
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} else {
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w += nexthop_nh->nh_weight;
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upper_bound = DIV_ROUND_CLOSEST(2147483648LL * w,
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total) - 1;
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}
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atomic_set(&nexthop_nh->nh_upper_bound, upper_bound);
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} endfor_nexthops(fi);
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net_get_random_once(&fib_multipath_secret,
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sizeof(fib_multipath_secret));
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}
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static inline void fib_add_weight(struct fib_info *fi,
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const struct fib_nh *nh)
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{
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fi->fib_weight += nh->nh_weight;
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}
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#else /* CONFIG_IP_ROUTE_MULTIPATH */
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#define fib_rebalance(fi) do { } while (0)
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#define fib_add_weight(fi, nh) do { } while (0)
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#endif /* CONFIG_IP_ROUTE_MULTIPATH */
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static int fib_encap_match(struct net *net, u16 encap_type,
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struct nlattr *encap,
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@ -1094,8 +1153,11 @@ struct fib_info *fib_create_info(struct fib_config *cfg)
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change_nexthops(fi) {
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fib_info_update_nh_saddr(net, nexthop_nh);
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fib_add_weight(fi, nexthop_nh);
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} endfor_nexthops(fi)
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fib_rebalance(fi);
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link_it:
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ofi = fib_find_info(fi);
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if (ofi) {
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@ -1317,12 +1379,6 @@ int fib_sync_down_dev(struct net_device *dev, unsigned long event)
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nexthop_nh->nh_flags |= RTNH_F_LINKDOWN;
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break;
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}
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#ifdef CONFIG_IP_ROUTE_MULTIPATH
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spin_lock_bh(&fib_multipath_lock);
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fi->fib_power -= nexthop_nh->nh_power;
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nexthop_nh->nh_power = 0;
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spin_unlock_bh(&fib_multipath_lock);
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#endif
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dead++;
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}
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#ifdef CONFIG_IP_ROUTE_MULTIPATH
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@ -1345,6 +1401,8 @@ int fib_sync_down_dev(struct net_device *dev, unsigned long event)
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}
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ret++;
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}
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fib_rebalance(fi);
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}
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return ret;
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@ -1467,20 +1525,15 @@ int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
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!__in_dev_get_rtnl(dev))
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continue;
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alive++;
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#ifdef CONFIG_IP_ROUTE_MULTIPATH
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spin_lock_bh(&fib_multipath_lock);
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nexthop_nh->nh_power = 0;
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nexthop_nh->nh_flags &= ~nh_flags;
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spin_unlock_bh(&fib_multipath_lock);
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#else
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nexthop_nh->nh_flags &= ~nh_flags;
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#endif
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} endfor_nexthops(fi)
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if (alive > 0) {
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fi->fib_flags &= ~nh_flags;
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ret++;
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}
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fib_rebalance(fi);
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}
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return ret;
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@ -1488,62 +1541,19 @@ int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
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#ifdef CONFIG_IP_ROUTE_MULTIPATH
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/*
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* The algorithm is suboptimal, but it provides really
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* fair weighted route distribution.
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*/
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void fib_select_multipath(struct fib_result *res)
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void fib_select_multipath(struct fib_result *res, int hash)
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{
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struct fib_info *fi = res->fi;
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struct in_device *in_dev;
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int w;
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spin_lock_bh(&fib_multipath_lock);
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if (fi->fib_power <= 0) {
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int power = 0;
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change_nexthops(fi) {
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in_dev = __in_dev_get_rcu(nexthop_nh->nh_dev);
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if (nexthop_nh->nh_flags & RTNH_F_DEAD)
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continue;
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if (in_dev &&
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IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
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nexthop_nh->nh_flags & RTNH_F_LINKDOWN)
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continue;
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power += nexthop_nh->nh_weight;
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nexthop_nh->nh_power = nexthop_nh->nh_weight;
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} endfor_nexthops(fi);
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fi->fib_power = power;
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if (power <= 0) {
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spin_unlock_bh(&fib_multipath_lock);
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/* Race condition: route has just become dead. */
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res->nh_sel = 0;
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return;
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}
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}
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for_nexthops(fi) {
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if (hash > atomic_read(&nh->nh_upper_bound))
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continue;
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/* w should be random number [0..fi->fib_power-1],
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* it is pretty bad approximation.
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*/
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w = jiffies % fi->fib_power;
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change_nexthops(fi) {
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if (!(nexthop_nh->nh_flags & RTNH_F_DEAD) &&
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nexthop_nh->nh_power) {
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w -= nexthop_nh->nh_power;
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if (w <= 0) {
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nexthop_nh->nh_power--;
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fi->fib_power--;
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res->nh_sel = nhsel;
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spin_unlock_bh(&fib_multipath_lock);
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return;
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}
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}
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res->nh_sel = nhsel;
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return;
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} endfor_nexthops(fi);
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/* Race condition: route has just become dead. */
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res->nh_sel = 0;
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spin_unlock_bh(&fib_multipath_lock);
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}
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#endif
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@ -1658,8 +1658,12 @@ static int ip_mkroute_input(struct sk_buff *skb,
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__be32 daddr, __be32 saddr, u32 tos)
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{
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#ifdef CONFIG_IP_ROUTE_MULTIPATH
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if (res->fi && res->fi->fib_nhs > 1)
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fib_select_multipath(res);
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if (res->fi && res->fi->fib_nhs > 1) {
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int h;
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h = fib_multipath_hash(saddr, daddr);
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fib_select_multipath(res, h);
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}
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#endif
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/* create a routing cache entry */
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@ -2189,8 +2193,12 @@ struct rtable *__ip_route_output_key(struct net *net, struct flowi4 *fl4)
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}
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#ifdef CONFIG_IP_ROUTE_MULTIPATH
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if (res.fi->fib_nhs > 1 && fl4->flowi4_oif == 0)
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fib_select_multipath(&res);
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if (res.fi->fib_nhs > 1 && fl4->flowi4_oif == 0) {
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int h;
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h = fib_multipath_hash(fl4->saddr, fl4->daddr);
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fib_select_multipath(&res, h);
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}
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else
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#endif
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if (!res.prefixlen &&
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