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6ab3d5624e
Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
251 lines
5.3 KiB
C
251 lines
5.3 KiB
C
/*
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* Device round robin policy for multipath.
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*
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*
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* Version: $Id: multipath_drr.c,v 1.1.2.1 2004/09/16 07:42:34 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 <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/module.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_mp_alg.h>
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struct multipath_device {
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int ifi; /* interface index of device */
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atomic_t usecount;
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int allocated;
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};
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#define MULTIPATH_MAX_DEVICECANDIDATES 10
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static struct multipath_device state[MULTIPATH_MAX_DEVICECANDIDATES];
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static DEFINE_SPINLOCK(state_lock);
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static int inline __multipath_findslot(void)
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{
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int i;
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for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++) {
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if (state[i].allocated == 0)
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return i;
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}
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return -1;
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}
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static int inline __multipath_finddev(int ifindex)
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{
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int i;
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for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++) {
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if (state[i].allocated != 0 &&
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state[i].ifi == ifindex)
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return i;
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}
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return -1;
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}
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static int drr_dev_event(struct notifier_block *this,
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unsigned long event, void *ptr)
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{
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struct net_device *dev = ptr;
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int devidx;
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switch (event) {
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case NETDEV_UNREGISTER:
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case NETDEV_DOWN:
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spin_lock_bh(&state_lock);
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devidx = __multipath_finddev(dev->ifindex);
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if (devidx != -1) {
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state[devidx].allocated = 0;
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state[devidx].ifi = 0;
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atomic_set(&state[devidx].usecount, 0);
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}
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spin_unlock_bh(&state_lock);
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break;
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};
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return NOTIFY_DONE;
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}
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static struct notifier_block drr_dev_notifier = {
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.notifier_call = drr_dev_event,
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};
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static void drr_safe_inc(atomic_t *usecount)
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{
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int n;
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atomic_inc(usecount);
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n = atomic_read(usecount);
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if (n <= 0) {
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int i;
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spin_lock_bh(&state_lock);
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for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++)
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atomic_set(&state[i].usecount, 0);
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spin_unlock_bh(&state_lock);
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}
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}
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static void drr_select_route(const struct flowi *flp,
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struct rtable *first, struct rtable **rp)
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{
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struct rtable *nh, *result, *cur_min;
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int min_usecount = -1;
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int devidx = -1;
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int cur_min_devidx = -1;
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/* 1. make sure all alt. nexthops have the same GC related data */
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/* 2. determine the new candidate to be returned */
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result = NULL;
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cur_min = NULL;
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for (nh = rcu_dereference(first); nh;
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nh = rcu_dereference(nh->u.rt_next)) {
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if ((nh->u.dst.flags & DST_BALANCED) != 0 &&
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multipath_comparekeys(&nh->fl, flp)) {
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int nh_ifidx = nh->u.dst.dev->ifindex;
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nh->u.dst.lastuse = jiffies;
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nh->u.dst.__use++;
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if (result != NULL)
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continue;
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/* search for the output interface */
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/* this is not SMP safe, only add/remove are
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* SMP safe as wrong usecount updates have no big
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* impact
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*/
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devidx = __multipath_finddev(nh_ifidx);
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if (devidx == -1) {
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/* add the interface to the array
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* SMP safe
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*/
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spin_lock_bh(&state_lock);
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/* due to SMP: search again */
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devidx = __multipath_finddev(nh_ifidx);
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if (devidx == -1) {
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/* add entry for device */
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devidx = __multipath_findslot();
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if (devidx == -1) {
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/* unlikely but possible */
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continue;
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}
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state[devidx].allocated = 1;
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state[devidx].ifi = nh_ifidx;
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atomic_set(&state[devidx].usecount, 0);
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min_usecount = 0;
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}
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spin_unlock_bh(&state_lock);
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}
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if (min_usecount == 0) {
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/* if the device has not been used it is
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* the primary target
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*/
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drr_safe_inc(&state[devidx].usecount);
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result = nh;
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} else {
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int count =
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atomic_read(&state[devidx].usecount);
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if (min_usecount == -1 ||
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count < min_usecount) {
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cur_min = nh;
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cur_min_devidx = devidx;
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min_usecount = count;
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}
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}
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}
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}
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if (!result) {
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if (cur_min) {
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drr_safe_inc(&state[cur_min_devidx].usecount);
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result = cur_min;
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} else {
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result = first;
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}
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}
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*rp = result;
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}
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static struct ip_mp_alg_ops drr_ops = {
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.mp_alg_select_route = drr_select_route,
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};
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static int __init drr_init(void)
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{
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int err = register_netdevice_notifier(&drr_dev_notifier);
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if (err)
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return err;
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err = multipath_alg_register(&drr_ops, IP_MP_ALG_DRR);
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if (err)
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goto fail;
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return 0;
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fail:
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unregister_netdevice_notifier(&drr_dev_notifier);
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return err;
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}
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static void __exit drr_exit(void)
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{
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unregister_netdevice_notifier(&drr_dev_notifier);
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multipath_alg_unregister(&drr_ops, IP_MP_ALG_DRR);
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}
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module_init(drr_init);
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module_exit(drr_exit);
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MODULE_LICENSE("GPL");
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