129 lines
3.0 KiB
C
129 lines
3.0 KiB
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 <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
|
|
|
|
/* 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 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)
|
|
random(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");
|