LXR linux/net/ipv4/ipvs/ip_vs

   1/*
   2 * IPVS:        Round-Robin Scheduling module
   3 *
   4 * Version:     $Id: ip_vs_rr.c,v 1.9 2002/09/15 08:14:08 wensong Exp $
   5 *
   6 * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
   7 *              Peter Kese <peter.kese@ijs.si>
   8 *
   9 *              This program is free software; you can redistribute it and/or
  10 *              modify it under the terms of the GNU General Public License
  11 *              as published by the Free Software Foundation; either version
  12 *              2 of the License, or (at your option) any later version.
  13 *
  14 * Fixes/Changes:
  15 *     Wensong Zhang            :     changed the ip_vs_rr_schedule to return dest
  16 *     Julian Anastasov         :     fixed the NULL pointer access bug in debugging
  17 *     Wensong Zhang            :     changed some comestics things for debugging
  18 *     Wensong Zhang            :     changed for the d-linked destination list
  19 *     Wensong Zhang            :     added the ip_vs_rr_update_svc
  20 *     Wensong Zhang            :     added any dest with weight=0 is quiesced
  21 *
  22 */
  23
  24#include <linux/module.h>
  25#include <linux/kernel.h>
  26
  27#include <net/ip_vs.h>
  28
  29
  30static int ip_vs_rr_init_svc(struct ip_vs_service *svc)
  31{
  32        svc->sched_data = &svc->destinations;
  33        return 0;
  34}
  35
  36
  37static int ip_vs_rr_done_svc(struct ip_vs_service *svc)
  38{
  39        return 0;
  40}
  41
  42
  43static int ip_vs_rr_update_svc(struct ip_vs_service *svc)
  44{
  45        svc->sched_data = &svc->destinations;
  46        return 0;
  47}
  48
  49
  50/*
  51 * Round-Robin Scheduling
  52 */
  53static struct ip_vs_dest *
  54ip_vs_rr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
  55{
  56        struct list_head *p, *q;
  57        struct ip_vs_dest *dest;
  58
  59        IP_VS_DBG(6, "ip_vs_rr_schedule(): Scheduling...\n");
  60
  61        write_lock(&svc->sched_lock);
  62        p = (struct list_head *)svc->sched_data;
  63        p = p->next;
  64        q = p;
  65        do {
  66                /* skip list head */
  67                if (q == &svc->destinations) {
  68                        q = q->next;
  69                        continue;
  70                }
  71
  72                dest = list_entry(q, struct ip_vs_dest, n_list);
  73                if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
  74                    atomic_read(&dest->weight) > 0)
  75                        /* HIT */
  76                        goto out;
  77                q = q->next;
  78        } while (q != p);
  79        write_unlock(&svc->sched_lock);
  80        return NULL;
  81
  82  out:
  83        svc->sched_data = q;
  84        write_unlock(&svc->sched_lock);
  85        IP_VS_DBG(6, "RR: server %u.%u.%u.%u:%u "
  86                  "activeconns %d refcnt %d weight %d\n",
  87                  NIPQUAD(dest->addr), ntohs(dest->port),
  88                  atomic_read(&dest->activeconns),
  89                  atomic_read(&dest->refcnt), atomic_read(&dest->weight));
  90
  91        return dest;
  92}
  93
  94
  95static struct ip_vs_scheduler ip_vs_rr_scheduler = {
  96        .name =                 "rr",                   /* name */
  97        .refcnt =               ATOMIC_INIT(0),
  98        .module =               THIS_MODULE,
  99        .init_service =         ip_vs_rr_init_svc,
 100        .done_service =         ip_vs_rr_done_svc,
 101        .update_service =       ip_vs_rr_update_svc,
 102        .schedule =             ip_vs_rr_schedule,
 103};
 104
 105static int __init ip_vs_rr_init(void)
 106{
 107        INIT_LIST_HEAD(&ip_vs_rr_scheduler.n_list);
 108        return register_ip_vs_scheduler(&ip_vs_rr_scheduler);
 109}
 110
 111static void __exit ip_vs_rr_cleanup(void)
 112{
 113        unregister_ip_vs_scheduler(&ip_vs_rr_scheduler);
 114}
 115
 116module_init(ip_vs_rr_init);
 117module_exit(ip_vs_rr_cleanup);
 118MODULE_LICENSE("GPL");
 119