--- /dev/null
+/*
+ * 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 <elueck@de.ibm.com><lkml@einar-lueck.de>
+ *
+ * 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 <linux/config.h>
+#include <asm/system.h>
+#include <asm/uaccess.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/timer.h>
+#include <linux/mm.h>
+#include <linux/kernel.h>
+#include <linux/fcntl.h>
+#include <linux/stat.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/inetdevice.h>
+#include <linux/igmp.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/module.h>
+#include <linux/mroute.h>
+#include <linux/init.h>
+#include <net/ip.h>
+#include <net/protocol.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/icmp.h>
+#include <net/udp.h>
+#include <net/raw.h>
+#include <linux/notifier.h>
+#include <linux/if_arp.h>
+#include <linux/netfilter_ipv4.h>
+#include <net/ipip.h>
+#include <net/checksum.h>
+#include <net/ip_fib.h>
+#include <net/ip_mp_alg.h>
+
+#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);
+MODULE_LICENSE("GPL");
git://git.onelab.eu / linux-2.6.git / blobdiff