/*
* 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 <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;
__be32 netmask;
__be32 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;
__be32 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) {
__be32 targetnetwork = fl->fl4_dst &
inet_make_mask(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.dst.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;
kfree(last_mpc);
last_mpc = mpc;
}
/* concurrent __multipath_flush may lead to !last_mpc */
kfree(last_mpc);
decision->u.dst.__use++;
*rp = decision;
}
static void wrandom_set_nhinfo(__be32 network,
__be32 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_bh(&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_bh(&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_bh(&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_bh(&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");
