net/ipv4/ipvs/ip_vs_rr.c

   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
  30 static int ip_vs_rr_init_svc(struct ip_vs_service *svc)
  31 {
  32         svc->sched_data = &svc->destinations;
  33         return 0;
  34 }
  35
  36
  37 static int ip_vs_rr_done_svc(struct ip_vs_service *svc)
  38 {
  39         return 0;
  40 }
  41
  42
  43 static 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  */
  53 static struct ip_vs_dest *
  54 ip_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
  95 static 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
 105 static 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
 111 static void __exit ip_vs_rr_cleanup(void)
 112 {
 113         unregister_ip_vs_scheduler(&ip_vs_rr_scheduler);
 114 }
 115
 116 module_init(ip_vs_rr_init);
 117 module_exit(ip_vs_rr_cleanup);
 118 MODULE_LICENSE("GPL");