[net-next-2.6.git] / net / ipv4 / multipath_random.c

/*
 *              Random policy for multipath.
 *
 *
 * Version:	$Id: multipath_random.c,v 1.1.2.3 2004/09/21 08:42:11 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 <asm/system.h>
#include <asm/uaccess.h>
#include <linux/types.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 <linux/random.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_mp_alg.h>

#define MULTIPATH_MAX_CANDIDATES 40

static void random_select_route(const struct flowi *flp,
				struct rtable *first,
				struct rtable **rp)
{
	struct rtable *rt;
	struct rtable *decision;
	unsigned char candidate_count = 0;

	/* count all candidate */
	for (rt = rcu_dereference(first); rt;
	     rt = rcu_dereference(rt->u.dst.rt_next)) {
		if ((rt->u.dst.flags & DST_BALANCED) != 0 &&
		    multipath_comparekeys(&rt->fl, flp))
			++candidate_count;
	}

	/* choose a random candidate */
	decision = first;
	if (candidate_count > 1) {
		unsigned char i = 0;
		unsigned char candidate_no = (unsigned char)
			(random32() % candidate_count);

		/* find chosen candidate and adjust GC data for all candidates
		 * to ensure they stay in cache
		 */
		for (rt = first; rt; rt = rt->u.dst.rt_next) {
			if ((rt->u.dst.flags & DST_BALANCED) != 0 &&
			    multipath_comparekeys(&rt->fl, flp)) {
				rt->u.dst.lastuse = jiffies;

				if (i == candidate_no)
					decision = rt;

				if (i >= candidate_count)
					break;

				i++;
			}
		}
	}

	decision->u.dst.__use++;
	*rp = decision;
}

static struct ip_mp_alg_ops random_ops = {
	.mp_alg_select_route	=	random_select_route,
};

static int __init random_init(void)
{
	return multipath_alg_register(&random_ops, IP_MP_ALG_RANDOM);
}

static void __exit random_exit(void)
{
	multipath_alg_unregister(&random_ops, IP_MP_ALG_RANDOM);
}

module_init(random_init);
module_exit(random_exit);
MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Random policy for multipath.
	3	*
	4	*
	5	* Version: $Id: multipath_random.c,v 1.1.2.3 2004/09/21 08:42:11 elueck Exp $
	6	*
	7	* Authors: Einar Lueck <elueck@de.ibm.com><lkml@einar-lueck.de>
	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
1da177e4 LT	15	#include <asm/system.h>
	16	#include <asm/uaccess.h>
	17	#include <linux/types.h>
1da177e4 LT	18	#include <linux/errno.h>
	19	#include <linux/timer.h>
	20	#include <linux/mm.h>
	21	#include <linux/kernel.h>
	22	#include <linux/fcntl.h>
	23	#include <linux/stat.h>
	24	#include <linux/socket.h>
	25	#include <linux/in.h>
	26	#include <linux/inet.h>
	27	#include <linux/netdevice.h>
	28	#include <linux/inetdevice.h>
	29	#include <linux/igmp.h>
	30	#include <linux/proc_fs.h>
	31	#include <linux/seq_file.h>
6efd8455	32	#include <linux/module.h>
1da177e4 LT	33	#include <linux/mroute.h>
1da177e4 LT	34	#include <linux/init.h>
4c3ae4d7	35	#include <linux/random.h>
1da177e4 LT	36	#include <net/ip.h>
	37	#include <net/protocol.h>
	38	#include <linux/skbuff.h>
	39	#include <net/sock.h>
	40	#include <net/icmp.h>
	41	#include <net/udp.h>
	42	#include <net/raw.h>
	43	#include <linux/notifier.h>
	44	#include <linux/if_arp.h>
	45	#include <linux/netfilter_ipv4.h>
	46	#include <net/ipip.h>
	47	#include <net/checksum.h>
	48	#include <net/ip_mp_alg.h>
	49
	50	#define MULTIPATH_MAX_CANDIDATES 40
	51
1da177e4 LT	52	static void random_select_route(const struct flowi *flp,
	53	struct rtable *first,
	54	struct rtable **rp)
	55	{
	56	struct rtable *rt;
	57	struct rtable *decision;
	58	unsigned char candidate_count = 0;
	59
	60	/* count all candidate */
	61	for (rt = rcu_dereference(first); rt;
5ef213f6	62	rt = rcu_dereference(rt->u.dst.rt_next)) {
1da177e4 LT	63	if ((rt->u.dst.flags & DST_BALANCED) != 0 &&
	64	multipath_comparekeys(&rt->fl, flp))
	65	++candidate_count;
	66	}
	67
	68	/* choose a random candidate */
	69	decision = first;
	70	if (candidate_count > 1) {
	71	unsigned char i = 0;
	72	unsigned char candidate_no = (unsigned char)
4c3ae4d7	73	(random32() % candidate_count);
1da177e4 LT	74
	75	/* find chosen candidate and adjust GC data for all candidates
	76	* to ensure they stay in cache
	77	*/
5ef213f6	78	for (rt = first; rt; rt = rt->u.dst.rt_next) {
1da177e4 LT	79	if ((rt->u.dst.flags & DST_BALANCED) != 0 &&
	80	multipath_comparekeys(&rt->fl, flp)) {
	81	rt->u.dst.lastuse = jiffies;
	82
	83	if (i == candidate_no)
	84	decision = rt;
	85
	86	if (i >= candidate_count)
	87	break;
	88
	89	i++;
	90	}
	91	}
	92	}
	93
	94	decision->u.dst.__use++;
	95	*rp = decision;
	96	}
	97
	98	static struct ip_mp_alg_ops random_ops = {
	99	.mp_alg_select_route = random_select_route,
	100	};
	101
	102	static int __init random_init(void)
	103	{
	104	return multipath_alg_register(&random_ops, IP_MP_ALG_RANDOM);
	105	}
	106
	107	static void __exit random_exit(void)
	108	{
	109	multipath_alg_unregister(&random_ops, IP_MP_ALG_RANDOM);
	110	}
	111
	112	module_init(random_init);
	113	module_exit(random_exit);
6efd8455	114	MODULE_LICENSE("GPL");