/* *              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");