[linux.git] / net / ipv4 / multipath_wrandom.c

/*
 *              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 <[email protected]><[email protected]>
 *
 *		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");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Weighted random policy for multipath.
	3	*
	4	*
	5	* Version: $Id: multipath_wrandom.c,v 1.1.2.3 2004/09/22 07:51:40 elueck Exp $
	6	*
	7	* Authors: Einar Lueck <[email protected]><[email protected]>
	8	*
	9	* This program is free software; you can redistribute it and/or
	10	* modify it under the terms of the GNU General Public License
	11	* as published by the Free Software Foundation; either version
	12	* 2 of the License, or (at your option) any later version.
	13	*/
	14
	15	#include <linux/config.h>
	16	#include <asm/system.h>
	17	#include <asm/uaccess.h>
	18	#include <linux/types.h>
	19	#include <linux/sched.h>
	20	#include <linux/errno.h>
	21	#include <linux/timer.h>
	22	#include <linux/mm.h>
	23	#include <linux/kernel.h>
	24	#include <linux/fcntl.h>
	25	#include <linux/stat.h>
	26	#include <linux/socket.h>
	27	#include <linux/in.h>
	28	#include <linux/inet.h>
	29	#include <linux/netdevice.h>
	30	#include <linux/inetdevice.h>
	31	#include <linux/igmp.h>
	32	#include <linux/proc_fs.h>
	33	#include <linux/seq_file.h>
6efd8455	34	#include <linux/module.h>
1da177e4 LT	35	#include <linux/mroute.h>
	36	#include <linux/init.h>
	37	#include <net/ip.h>
	38	#include <net/protocol.h>
	39	#include <linux/skbuff.h>
	40	#include <net/sock.h>
	41	#include <net/icmp.h>
	42	#include <net/udp.h>
	43	#include <net/raw.h>
	44	#include <linux/notifier.h>
	45	#include <linux/if_arp.h>
	46	#include <linux/netfilter_ipv4.h>
	47	#include <net/ipip.h>
	48	#include <net/checksum.h>
	49	#include <net/ip_fib.h>
	50	#include <net/ip_mp_alg.h>
	51
	52	#define MULTIPATH_STATE_SIZE 15
	53
	54	struct multipath_candidate {
	55	struct multipath_candidate *next;
	56	int power;
	57	struct rtable *rt;
	58	};
	59
	60	struct multipath_dest {
	61	struct list_head list;
	62
	63	const struct fib_nh *nh_info;
	64	__u32 netmask;
	65	__u32 network;
	66	unsigned char prefixlen;
	67
	68	struct rcu_head rcu;
	69	};
	70
	71	struct multipath_bucket {
	72	struct list_head head;
	73	spinlock_t lock;
	74	};
	75
	76	struct multipath_route {
	77	struct list_head list;
	78
	79	int oif;
	80	__u32 gw;
	81	struct list_head dests;
	82
	83	struct rcu_head rcu;
	84	};
	85
	86	/* state: primarily weight per route information */
	87	static struct multipath_bucket state[MULTIPATH_STATE_SIZE];
	88
	89	/* interface to random number generation */
	90	static unsigned int RANDOM_SEED = 93186752;
	91
	92	static inline unsigned int random(unsigned int ubound)
	93	{
	94	static unsigned int a = 1588635695,
	95	q = 2,
	96	r = 1117695901;
	97	RANDOM_SEED = a(RANDOM_SEED % q) - r(RANDOM_SEED / q);
	98	return RANDOM_SEED % ubound;
99	}
100
101	static unsigned char __multipath_lookup_weight(const struct flowi *fl,
102	const struct rtable *rt)
103	{
104	const int state_idx = rt->idev->dev->ifindex % MULTIPATH_STATE_SIZE;
105	struct multipath_route *r;
106	struct multipath_route *target_route = NULL;
107	struct multipath_dest *d;
108	int weight = 1;
109
110	/* lookup the weight information for a certain route */
111	rcu_read_lock();
112
113	/* find state entry for gateway or add one if necessary */
114	list_for_each_entry_rcu(r, &state[state_idx].head, list) {
115	if (r->gw == rt->rt_gateway &&
116	r->oif == rt->idev->dev->ifindex) {
117	target_route = r;
118	break;
119	}
120	}
121
122	if (!target_route) {
123	/* this should not happen... but we are prepared */
124	printk( KERN_CRIT"%s: missing state for gateway: %u and " \
125	"device %d\n", __FUNCTION__, rt->rt_gateway,
126	rt->idev->dev->ifindex);
127	goto out;
128	}
129
130	/* find state entry for destination */
131	list_for_each_entry_rcu(d, &target_route->dests, list) {
132	__u32 targetnetwork = fl->fl4_dst &
133	(0xFFFFFFFF >> (32 - d->prefixlen));
134
135	if ((targetnetwork & d->netmask) == d->network) {
136	weight = d->nh_info->nh_weight;
137	goto out;
138	}
139	}
140
141	out:
142	rcu_read_unlock();
143	return weight;
144	}
145
146	static void wrandom_init_state(void)
147	{
148	int i;
149
150	for (i = 0; i < MULTIPATH_STATE_SIZE; ++i) {
151	INIT_LIST_HEAD(&state[i].head);
152	spin_lock_init(&state[i].lock);
153	}
154	}
155
156	static void wrandom_select_route(const struct flowi *flp,
157	struct rtable *first,
158	struct rtable **rp)
159	{
160	struct rtable *rt;
161	struct rtable *decision;
162	struct multipath_candidate *first_mpc = NULL;
163	struct multipath_candidate mpc, last_mpc = NULL;
164	int power = 0;
165	int last_power;
166	int selector;
167	const size_t size_mpc = sizeof(struct multipath_candidate);
168
169	/* collect all candidates and identify their weights */
170	for (rt = rcu_dereference(first); rt;
171	rt = rcu_dereference(rt->u.rt_next)) {
172	if ((rt->u.dst.flags & DST_BALANCED) != 0 &&
173	multipath_comparekeys(&rt->fl, flp)) {
174	struct multipath_candidate* mpc =
175	(struct multipath_candidate*)
60d53065	176	kmalloc(size_mpc, GFP_ATOMIC);
1da177e4 LT	177
	178	if (!mpc)
	179	return;
	180
	181	power += __multipath_lookup_weight(flp, rt) * 10000;
	182
	183	mpc->power = power;
	184	mpc->rt = rt;
	185	mpc->next = NULL;
	186
	187	if (!first_mpc)
	188	first_mpc = mpc;
	189	else
	190	last_mpc->next = mpc;
	191
	192	last_mpc = mpc;
	193	}
	194	}
	195
	196	/* choose a weighted random candidate */
	197	decision = first;
	198	selector = random(power);
	199	last_power = 0;
	200
	201	/* select candidate, adjust GC data and cleanup local state */
	202	decision = first;
	203	last_mpc = NULL;
	204	for (mpc = first_mpc; mpc; mpc = mpc->next) {
	205	mpc->rt->u.dst.lastuse = jiffies;
	206	if (last_power <= selector && selector < mpc->power)
	207	decision = mpc->rt;
	208
	209	last_power = mpc->power;
	210	if (last_mpc)
	211	kfree(last_mpc);
	212
	213	last_mpc = mpc;
	214	}
	215
	216	if (last_mpc) {
	217	/* concurrent __multipath_flush may lead to !last_mpc */
	218	kfree(last_mpc);
	219	}
	220
	221	decision->u.dst.__use++;
	222	*rp = decision;
	223	}
	224
	225	static void wrandom_set_nhinfo(__u32 network,
	226	__u32 netmask,
	227	unsigned char prefixlen,
	228	const struct fib_nh *nh)
	229	{
	230	const int state_idx = nh->nh_oif % MULTIPATH_STATE_SIZE;
	231	struct multipath_route r, target_route = NULL;
	232	struct multipath_dest d, target_dest = NULL;
	233
	234	/* store the weight information for a certain route */
	235	spin_lock(&state[state_idx].lock);
	236
	237	/* find state entry for gateway or add one if necessary */
	238	list_for_each_entry_rcu(r, &state[state_idx].head, list) {
	239	if (r->gw == nh->nh_gw && r->oif == nh->nh_oif) {
	240	target_route = r;
241	break;
242	}
243	}
244
245	if (!target_route) {
246	const size_t size_rt = sizeof(struct multipath_route);
247	target_route = (struct multipath_route *)
60d53065	248	kmalloc(size_rt, GFP_ATOMIC);
1da177e4 LT	249
	250	target_route->gw = nh->nh_gw;
	251	target_route->oif = nh->nh_oif;
	252	memset(&target_route->rcu, 0, sizeof(struct rcu_head));
	253	INIT_LIST_HEAD(&target_route->dests);
	254
	255	list_add_rcu(&target_route->list, &state[state_idx].head);
	256	}
	257
	258	/* find state entry for destination or add one if necessary */
	259	list_for_each_entry_rcu(d, &target_route->dests, list) {
	260	if (d->nh_info == nh) {
	261	target_dest = d;
	262	break;
	263	}
	264	}
	265
	266	if (!target_dest) {
	267	const size_t size_dst = sizeof(struct multipath_dest);
	268	target_dest = (struct multipath_dest*)
60d53065	269	kmalloc(size_dst, GFP_ATOMIC);
1da177e4 LT	270
	271	target_dest->nh_info = nh;
	272	target_dest->network = network;
	273	target_dest->netmask = netmask;
	274	target_dest->prefixlen = prefixlen;
	275	memset(&target_dest->rcu, 0, sizeof(struct rcu_head));
	276
	277	list_add_rcu(&target_dest->list, &target_route->dests);
	278	}
	279	/* else: we already stored this info for another destination =>
	280	* we are finished
	281	*/
	282
	283	spin_unlock(&state[state_idx].lock);
	284	}
	285
	286	static void __multipath_free(struct rcu_head *head)
	287	{
	288	struct multipath_route *rt = container_of(head, struct multipath_route,
	289	rcu);
	290	kfree(rt);
	291	}
	292
	293	static void __multipath_free_dst(struct rcu_head *head)
	294	{
	295	struct multipath_dest *dst = container_of(head,
	296	struct multipath_dest,
	297	rcu);
	298	kfree(dst);
	299	}
	300
	301	static void wrandom_flush(void)
	302	{
	303	int i;
	304
	305	/* defere delete to all entries */
	306	for (i = 0; i < MULTIPATH_STATE_SIZE; ++i) {
	307	struct multipath_route *r;
	308
	309	spin_lock(&state[i].lock);
	310	list_for_each_entry_rcu(r, &state[i].head, list) {
	311	struct multipath_dest *d;
	312	list_for_each_entry_rcu(d, &r->dests, list) {
	313	list_del_rcu(&d->list);
	314	call_rcu(&d->rcu,
	315	__multipath_free_dst);
	316	}
	317	list_del_rcu(&r->list);
	318	call_rcu(&r->rcu,
	319	__multipath_free);
	320	}
	321
	322	spin_unlock(&state[i].lock);
	323	}
	324	}
	325
	326	static struct ip_mp_alg_ops wrandom_ops = {
	327	.mp_alg_select_route = wrandom_select_route,
	328	.mp_alg_flush = wrandom_flush,
	329	.mp_alg_set_nhinfo = wrandom_set_nhinfo,
	330	};
	331
	332	static int __init wrandom_init(void)
	333	{
334	wrandom_init_state();
335
336	return multipath_alg_register(&wrandom_ops, IP_MP_ALG_WRANDOM);
337	}
338
339	static void __exit wrandom_exit(void)
340	{
341	multipath_alg_unregister(&wrandom_ops, IP_MP_ALG_WRANDOM);
342	}
343
344	module_init(wrandom_init);
345	module_exit(wrandom_exit);
6efd8455	346	MODULE_LICENSE("GPL");