1 files changed, 344 insertions, 0 deletions
diff --git a/net/ipv4/multipath_wrandom.c b/net/ipv4/multipath_wrandom.c
new file mode 100644
index 00000000000..10b23e1bece
--- /dev/null
+++ b/net/ipv4/multipath_wrandom.c
@@ -0,0 +1,344 @@
+/*
+ *              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/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_KERNEL);
+
+			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_KERNEL);
+
+		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_KERNEL);
+
+		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);