/* * Weighted random policy for multipath. * * * Version: $Id: multipath_wrandom.c,v 1.1.2.3 2004/09/22 07:51:40 elueck Exp $ * * Authors: Einar Lueck * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define MULTIPATH_STATE_SIZE 15 struct multipath_candidate { struct multipath_candidate *next; int power; struct rtable *rt; }; struct multipath_dest { struct list_head list; const struct fib_nh *nh_info; __u32 netmask; __u32 network; unsigned char prefixlen; struct rcu_head rcu; }; struct multipath_bucket { struct list_head head; spinlock_t lock; }; struct multipath_route { struct list_head list; int oif; __u32 gw; struct list_head dests; struct rcu_head rcu; }; /* state: primarily weight per route information */ static struct multipath_bucket state[MULTIPATH_STATE_SIZE]; /* interface to random number generation */ static unsigned int RANDOM_SEED = 93186752; static inline unsigned int random(unsigned int ubound) { static unsigned int a = 1588635695, q = 2, r = 1117695901; RANDOM_SEED = a*(RANDOM_SEED % q) - r*(RANDOM_SEED / q); return RANDOM_SEED % ubound; } static unsigned char __multipath_lookup_weight(const struct flowi *fl, const struct rtable *rt) { const int state_idx = rt->idev->dev->ifindex % MULTIPATH_STATE_SIZE; struct multipath_route *r; struct multipath_route *target_route = NULL; struct multipath_dest *d; int weight = 1; /* lookup the weight information for a certain route */ rcu_read_lock(); /* find state entry for gateway or add one if necessary */ list_for_each_entry_rcu(r, &state[state_idx].head, list) { if (r->gw == rt->rt_gateway && r->oif == rt->idev->dev->ifindex) { target_route = r; break; } } if (!target_route) { /* this should not happen... but we are prepared */ printk( KERN_CRIT"%s: missing state for gateway: %u and " \ "device %d\n", __FUNCTION__, rt->rt_gateway, rt->idev->dev->ifindex); goto out; } /* find state entry for destination */ list_for_each_entry_rcu(d, &target_route->dests, list) { __u32 targetnetwork = fl->fl4_dst & (0xFFFFFFFF >> (32 - d->prefixlen)); if ((targetnetwork & d->netmask) == d->network) { weight = d->nh_info->nh_weight; goto out; } } out: rcu_read_unlock(); return weight; } static void wrandom_init_state(void) { int i; for (i = 0; i < MULTIPATH_STATE_SIZE; ++i) { INIT_LIST_HEAD(&state[i].head); spin_lock_init(&state[i].lock); } } static void wrandom_select_route(const struct flowi *flp, struct rtable *first, struct rtable **rp) { struct rtable *rt; struct rtable *decision; struct multipath_candidate *first_mpc = NULL; struct multipath_candidate *mpc, *last_mpc = NULL; int power = 0; int last_power; int selector; const size_t size_mpc = sizeof(struct multipath_candidate); /* collect all candidates and identify their weights */ for (rt = rcu_dereference(first); rt; rt = rcu_dereference(rt->u.rt_next)) { if ((rt->u.dst.flags & DST_BALANCED) != 0 && multipath_comparekeys(&rt->fl, flp)) { struct multipath_candidate* mpc = (struct multipath_candidate*) kmalloc(size_mpc, GFP_ATOMIC); if (!mpc) return; power += __multipath_lookup_weight(flp, rt) * 10000; mpc->power = power; mpc->rt = rt; mpc->next = NULL; if (!first_mpc) first_mpc = mpc; else last_mpc->next = mpc; last_mpc = mpc; } } /* choose a weighted random candidate */ decision = first; selector = random(power); last_power = 0; /* select candidate, adjust GC data and cleanup local state */ decision = first; last_mpc = NULL; for (mpc = first_mpc; mpc; mpc = mpc->next) { mpc->rt->u.dst.lastuse = jiffies; if (last_power <= selector && selector < mpc->power) decision = mpc->rt; last_power = mpc->power; if (last_mpc) kfree(last_mpc); last_mpc = mpc; } if (last_mpc) { /* concurrent __multipath_flush may lead to !last_mpc */ kfree(last_mpc); } decision->u.dst.__use++; *rp = decision; } static void wrandom_set_nhinfo(__u32 network, __u32 netmask, unsigned char prefixlen, const struct fib_nh *nh) { const int state_idx = nh->nh_oif % MULTIPATH_STATE_SIZE; struct multipath_route *r, *target_route = NULL; struct multipath_dest *d, *target_dest = NULL; /* store the weight information for a certain route */ spin_lock(&state[state_idx].lock); /* find state entry for gateway or add one if necessary */ list_for_each_entry_rcu(r, &state[state_idx].head, list) { if (r->gw == nh->nh_gw && r->oif == nh->nh_oif) { target_route = r; break; } } if (!target_route) { const size_t size_rt = sizeof(struct multipath_route); target_route = (struct multipath_route *) kmalloc(size_rt, GFP_ATOMIC); target_route->gw = nh->nh_gw; target_route->oif = nh->nh_oif; memset(&target_route->rcu, 0, sizeof(struct rcu_head)); INIT_LIST_HEAD(&target_route->dests); list_add_rcu(&target_route->list, &state[state_idx].head); } /* find state entry for destination or add one if necessary */ list_for_each_entry_rcu(d, &target_route->dests, list) { if (d->nh_info == nh) { target_dest = d; break; } } if (!target_dest) { const size_t size_dst = sizeof(struct multipath_dest); target_dest = (struct multipath_dest*) kmalloc(size_dst, GFP_ATOMIC); target_dest->nh_info = nh; target_dest->network = network; target_dest->netmask = netmask; target_dest->prefixlen = prefixlen; memset(&target_dest->rcu, 0, sizeof(struct rcu_head)); list_add_rcu(&target_dest->list, &target_route->dests); } /* else: we already stored this info for another destination => * we are finished */ spin_unlock(&state[state_idx].lock); } static void __multipath_free(struct rcu_head *head) { struct multipath_route *rt = container_of(head, struct multipath_route, rcu); kfree(rt); } static void __multipath_free_dst(struct rcu_head *head) { struct multipath_dest *dst = container_of(head, struct multipath_dest, rcu); kfree(dst); } static void wrandom_flush(void) { int i; /* defere delete to all entries */ for (i = 0; i < MULTIPATH_STATE_SIZE; ++i) { struct multipath_route *r; spin_lock(&state[i].lock); list_for_each_entry_rcu(r, &state[i].head, list) { struct multipath_dest *d; list_for_each_entry_rcu(d, &r->dests, list) { list_del_rcu(&d->list); call_rcu(&d->rcu, __multipath_free_dst); } list_del_rcu(&r->list); call_rcu(&r->rcu, __multipath_free); } spin_unlock(&state[i].lock); } } static struct ip_mp_alg_ops wrandom_ops = { .mp_alg_select_route = wrandom_select_route, .mp_alg_flush = wrandom_flush, .mp_alg_set_nhinfo = wrandom_set_nhinfo, }; static int __init wrandom_init(void) { wrandom_init_state(); return multipath_alg_register(&wrandom_ops, IP_MP_ALG_WRANDOM); } static void __exit wrandom_exit(void) { multipath_alg_unregister(&wrandom_ops, IP_MP_ALG_WRANDOM); } module_init(wrandom_init); module_exit(wrandom_exit);