345 lines
8.0 KiB
C
345 lines
8.0 KiB
C
/*
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* Weighted random policy for multipath.
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*
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*
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* Version: $Id: multipath_wrandom.c,v 1.1.2.3 2004/09/22 07:51:40 elueck Exp $
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*
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* Authors: Einar Lueck <elueck@de.ibm.com><lkml@einar-lueck.de>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/config.h>
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#include <asm/system.h>
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#include <asm/uaccess.h>
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#include <linux/types.h>
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#include <linux/sched.h>
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#include <linux/errno.h>
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#include <linux/timer.h>
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#include <linux/mm.h>
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#include <linux/kernel.h>
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#include <linux/fcntl.h>
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#include <linux/stat.h>
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#include <linux/socket.h>
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#include <linux/in.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/inetdevice.h>
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#include <linux/igmp.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <linux/mroute.h>
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#include <linux/init.h>
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#include <net/ip.h>
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#include <net/protocol.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <net/icmp.h>
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#include <net/udp.h>
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#include <net/raw.h>
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#include <linux/notifier.h>
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#include <linux/if_arp.h>
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#include <linux/netfilter_ipv4.h>
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#include <net/ipip.h>
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#include <net/checksum.h>
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#include <net/ip_fib.h>
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#include <net/ip_mp_alg.h>
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#define MULTIPATH_STATE_SIZE 15
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struct multipath_candidate {
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struct multipath_candidate *next;
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int power;
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struct rtable *rt;
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};
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struct multipath_dest {
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struct list_head list;
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const struct fib_nh *nh_info;
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__u32 netmask;
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__u32 network;
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unsigned char prefixlen;
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struct rcu_head rcu;
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};
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struct multipath_bucket {
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struct list_head head;
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spinlock_t lock;
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};
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struct multipath_route {
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struct list_head list;
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int oif;
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__u32 gw;
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struct list_head dests;
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struct rcu_head rcu;
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};
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/* state: primarily weight per route information */
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static struct multipath_bucket state[MULTIPATH_STATE_SIZE];
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/* interface to random number generation */
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static unsigned int RANDOM_SEED = 93186752;
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static inline unsigned int random(unsigned int ubound)
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{
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static unsigned int a = 1588635695,
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q = 2,
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r = 1117695901;
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RANDOM_SEED = a*(RANDOM_SEED % q) - r*(RANDOM_SEED / q);
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return RANDOM_SEED % ubound;
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}
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static unsigned char __multipath_lookup_weight(const struct flowi *fl,
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const struct rtable *rt)
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{
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const int state_idx = rt->idev->dev->ifindex % MULTIPATH_STATE_SIZE;
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struct multipath_route *r;
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struct multipath_route *target_route = NULL;
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struct multipath_dest *d;
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int weight = 1;
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/* lookup the weight information for a certain route */
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rcu_read_lock();
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/* find state entry for gateway or add one if necessary */
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list_for_each_entry_rcu(r, &state[state_idx].head, list) {
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if (r->gw == rt->rt_gateway &&
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r->oif == rt->idev->dev->ifindex) {
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target_route = r;
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break;
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}
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}
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if (!target_route) {
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/* this should not happen... but we are prepared */
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printk( KERN_CRIT"%s: missing state for gateway: %u and " \
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"device %d\n", __FUNCTION__, rt->rt_gateway,
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rt->idev->dev->ifindex);
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goto out;
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}
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/* find state entry for destination */
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list_for_each_entry_rcu(d, &target_route->dests, list) {
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__u32 targetnetwork = fl->fl4_dst &
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(0xFFFFFFFF >> (32 - d->prefixlen));
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if ((targetnetwork & d->netmask) == d->network) {
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weight = d->nh_info->nh_weight;
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goto out;
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}
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}
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out:
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rcu_read_unlock();
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return weight;
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}
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static void wrandom_init_state(void)
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{
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int i;
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for (i = 0; i < MULTIPATH_STATE_SIZE; ++i) {
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INIT_LIST_HEAD(&state[i].head);
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spin_lock_init(&state[i].lock);
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}
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}
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static void wrandom_select_route(const struct flowi *flp,
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struct rtable *first,
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struct rtable **rp)
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{
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struct rtable *rt;
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struct rtable *decision;
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struct multipath_candidate *first_mpc = NULL;
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struct multipath_candidate *mpc, *last_mpc = NULL;
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int power = 0;
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int last_power;
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int selector;
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const size_t size_mpc = sizeof(struct multipath_candidate);
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/* collect all candidates and identify their weights */
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for (rt = rcu_dereference(first); rt;
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rt = rcu_dereference(rt->u.rt_next)) {
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if ((rt->u.dst.flags & DST_BALANCED) != 0 &&
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multipath_comparekeys(&rt->fl, flp)) {
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struct multipath_candidate* mpc =
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(struct multipath_candidate*)
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kmalloc(size_mpc, GFP_ATOMIC);
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if (!mpc)
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return;
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power += __multipath_lookup_weight(flp, rt) * 10000;
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mpc->power = power;
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mpc->rt = rt;
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mpc->next = NULL;
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if (!first_mpc)
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first_mpc = mpc;
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else
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last_mpc->next = mpc;
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last_mpc = mpc;
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}
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}
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/* choose a weighted random candidate */
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decision = first;
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selector = random(power);
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last_power = 0;
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/* select candidate, adjust GC data and cleanup local state */
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decision = first;
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last_mpc = NULL;
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for (mpc = first_mpc; mpc; mpc = mpc->next) {
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mpc->rt->u.dst.lastuse = jiffies;
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if (last_power <= selector && selector < mpc->power)
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decision = mpc->rt;
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last_power = mpc->power;
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if (last_mpc)
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kfree(last_mpc);
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last_mpc = mpc;
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}
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if (last_mpc) {
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/* concurrent __multipath_flush may lead to !last_mpc */
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kfree(last_mpc);
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}
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decision->u.dst.__use++;
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*rp = decision;
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}
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static void wrandom_set_nhinfo(__u32 network,
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__u32 netmask,
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unsigned char prefixlen,
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const struct fib_nh *nh)
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{
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const int state_idx = nh->nh_oif % MULTIPATH_STATE_SIZE;
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struct multipath_route *r, *target_route = NULL;
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struct multipath_dest *d, *target_dest = NULL;
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/* store the weight information for a certain route */
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spin_lock(&state[state_idx].lock);
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/* find state entry for gateway or add one if necessary */
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list_for_each_entry_rcu(r, &state[state_idx].head, list) {
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if (r->gw == nh->nh_gw && r->oif == nh->nh_oif) {
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target_route = r;
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break;
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}
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}
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if (!target_route) {
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const size_t size_rt = sizeof(struct multipath_route);
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target_route = (struct multipath_route *)
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kmalloc(size_rt, GFP_ATOMIC);
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target_route->gw = nh->nh_gw;
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target_route->oif = nh->nh_oif;
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memset(&target_route->rcu, 0, sizeof(struct rcu_head));
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INIT_LIST_HEAD(&target_route->dests);
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list_add_rcu(&target_route->list, &state[state_idx].head);
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}
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/* find state entry for destination or add one if necessary */
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list_for_each_entry_rcu(d, &target_route->dests, list) {
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if (d->nh_info == nh) {
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target_dest = d;
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break;
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}
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}
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if (!target_dest) {
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const size_t size_dst = sizeof(struct multipath_dest);
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target_dest = (struct multipath_dest*)
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kmalloc(size_dst, GFP_ATOMIC);
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target_dest->nh_info = nh;
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target_dest->network = network;
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target_dest->netmask = netmask;
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target_dest->prefixlen = prefixlen;
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memset(&target_dest->rcu, 0, sizeof(struct rcu_head));
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list_add_rcu(&target_dest->list, &target_route->dests);
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}
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/* else: we already stored this info for another destination =>
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* we are finished
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*/
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spin_unlock(&state[state_idx].lock);
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}
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static void __multipath_free(struct rcu_head *head)
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{
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struct multipath_route *rt = container_of(head, struct multipath_route,
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rcu);
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kfree(rt);
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}
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static void __multipath_free_dst(struct rcu_head *head)
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{
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struct multipath_dest *dst = container_of(head,
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struct multipath_dest,
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rcu);
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kfree(dst);
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}
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static void wrandom_flush(void)
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{
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int i;
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/* defere delete to all entries */
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for (i = 0; i < MULTIPATH_STATE_SIZE; ++i) {
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struct multipath_route *r;
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spin_lock(&state[i].lock);
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list_for_each_entry_rcu(r, &state[i].head, list) {
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struct multipath_dest *d;
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list_for_each_entry_rcu(d, &r->dests, list) {
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list_del_rcu(&d->list);
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call_rcu(&d->rcu,
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__multipath_free_dst);
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}
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list_del_rcu(&r->list);
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call_rcu(&r->rcu,
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__multipath_free);
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}
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spin_unlock(&state[i].lock);
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}
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}
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static struct ip_mp_alg_ops wrandom_ops = {
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.mp_alg_select_route = wrandom_select_route,
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.mp_alg_flush = wrandom_flush,
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.mp_alg_set_nhinfo = wrandom_set_nhinfo,
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};
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static int __init wrandom_init(void)
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{
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wrandom_init_state();
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return multipath_alg_register(&wrandom_ops, IP_MP_ALG_WRANDOM);
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}
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static void __exit wrandom_exit(void)
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{
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multipath_alg_unregister(&wrandom_ops, IP_MP_ALG_WRANDOM);
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}
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module_init(wrandom_init);
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module_exit(wrandom_exit);
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