root/net/netfilter/ipvs/ip_vs_rr.c

DEFINITIONS

1. ip_vs_rr_init_svc
2. ip_vs_rr_update_svc
3. ip_vs_rr_schedule
4. ip_vs_rr_init
5. ip_vs_rr_cleanup

/*
 * IPVS:        Round-Robin Scheduling module
 *
 * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
 *              Peter Kese <peter.kese@ijs.si>
 *
 *              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.
 *
 * Fixes/Changes:
 *     Wensong Zhang            :     changed the ip_vs_rr_schedule to return dest
 *     Julian Anastasov         :     fixed the NULL pointer access bug in debugging
 *     Wensong Zhang            :     changed some comestics things for debugging
 *     Wensong Zhang            :     changed for the d-linked destination list
 *     Wensong Zhang            :     added the ip_vs_rr_update_svc
 *     Wensong Zhang            :     added any dest with weight=0 is quiesced
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>

#include <net/ip_vs.h>


static int ip_vs_rr_init_svc(struct ip_vs_service *svc)
{
        svc->sched_data = &svc->destinations;
        return 0;
}


static int ip_vs_rr_update_svc(struct ip_vs_service *svc)
{
        svc->sched_data = &svc->destinations;
        return 0;
}


/*
 * Round-Robin Scheduling
 */
static struct ip_vs_dest *
ip_vs_rr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
{
        struct list_head *p, *q;
        struct ip_vs_dest *dest;

        IP_VS_DBG(6, "ip_vs_rr_schedule(): Scheduling...\n");

        write_lock(&svc->sched_lock);
        p = (struct list_head *)svc->sched_data;
        p = p->next;
        q = p;
        do {
                /* skip list head */
                if (q == &svc->destinations) {
                        q = q->next;
                        continue;
                }

                dest = list_entry(q, struct ip_vs_dest, n_list);
                if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
                    atomic_read(&dest->weight) > 0)
                        /* HIT */
                        goto out;
                q = q->next;
        } while (q != p);
        write_unlock(&svc->sched_lock);
        return NULL;

  out:
        svc->sched_data = q;
        write_unlock(&svc->sched_lock);
        IP_VS_DBG_BUF(6, "RR: server %s:%u "
                      "activeconns %d refcnt %d weight %d\n",
                      IP_VS_DBG_ADDR(svc->af, &dest->addr), ntohs(dest->port),
                      atomic_read(&dest->activeconns),
                      atomic_read(&dest->refcnt), atomic_read(&dest->weight));

        return dest;
}


static struct ip_vs_scheduler ip_vs_rr_scheduler = {
        .name =                 "rr",                   /* name */
        .refcnt =               ATOMIC_INIT(0),
        .module =               THIS_MODULE,
        .n_list =               LIST_HEAD_INIT(ip_vs_rr_scheduler.n_list),
#ifdef CONFIG_IP_VS_IPV6
        .supports_ipv6 =        1,
#endif
        .init_service =         ip_vs_rr_init_svc,
        .update_service =       ip_vs_rr_update_svc,
        .schedule =             ip_vs_rr_schedule,
};

static int __init ip_vs_rr_init(void)
{
        return register_ip_vs_scheduler(&ip_vs_rr_scheduler);
}

static void __exit ip_vs_rr_cleanup(void)
{
        unregister_ip_vs_scheduler(&ip_vs_rr_scheduler);
}

module_init(ip_vs_rr_init);
module_exit(ip_vs_rr_cleanup);
MODULE_LICENSE("GPL");