net/ipv4/ipvs/ip_vs_rr.c

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