/* * Round robin policy for multipath. * * * Version: $Id: multipath_rr.c,v 1.1.2.2 2004/09/16 07:42:34 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 <linux/config.h> #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/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 static struct rtable* last_used = NULL; static void rr_remove(struct rtable *rt) { if (last_used == rt) last_used = NULL; } static void rr_select_route(const struct flowi *flp, struct rtable *first, struct rtable **rp) { struct rtable *nh, *result, *min_use_cand = NULL; int min_use = -1; /* if necessary and possible utilize the old alternative */ if ((flp->flags & FLOWI_FLAG_MULTIPATHOLDROUTE) != 0 && last_used != NULL) { result = last_used; goto out; } /* 1. make sure all alt. nexthops have the same GC related data * 2. determine the new candidate to be returned */ result = NULL; for (nh = rcu_dereference(first); nh; nh = rcu_dereference(nh->u.rt_next)) { if ((nh->u.dst.flags & DST_BALANCED) != 0 && multipath_comparekeys(&nh->fl, flp)) { nh->u.dst.lastuse = jiffies; if (min_use == -1 || nh->u.dst.__use < min_use) { min_use = nh->u.dst.__use; min_use_cand = nh; } } } result = min_use_cand; if (!result) result = first; out: last_used = result; result->u.dst.__use++; *rp = result; } static struct ip_mp_alg_ops rr_ops = { .mp_alg_select_route = rr_select_route, .mp_alg_remove = rr_remove, }; static int __init rr_init(void) { return multipath_alg_register(&rr_ops, IP_MP_ALG_RR); } static void __exit rr_exit(void) { multipath_alg_unregister(&rr_ops, IP_MP_ALG_RR); } module_init(rr_init); module_exit(rr_exit);