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/*
* 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
*
*/
#define KMSG_COMPONENT "IPVS"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#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_del_dest(struct ip_vs_service *svc, struct ip_vs_dest *dest)
{
struct list_head *p;
spin_lock_bh(&svc->sched_lock);
p = (struct list_head *) svc->sched_data;
/* dest is already unlinked, so p->prev is not valid but
* p->next is valid, use it to reach previous entry.
*/
if (p == &dest->n_list)
svc->sched_data = p->next->prev;
spin_unlock_bh(&svc->sched_lock);
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 ip_vs_iphdr *iph)
{
struct list_head *p;
struct ip_vs_dest *dest, *last;
int pass = 0;
IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
spin_lock_bh(&svc->sched_lock);
p = (struct list_head *) svc->sched_data;
last = dest = list_entry(p, struct ip_vs_dest, n_list);
do {
list_for_each_entry_continue_rcu(dest,
&svc->destinations,
n_list) {
if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
atomic_read(&dest->weight) > 0)
/* HIT */
goto out;
if (dest == last)
goto stop;
}
pass++;
/* Previous dest could be unlinked, do not loop forever.
* If we stay at head there is no need for 2nd pass.
*/
} while (pass < 2 && p != &svc->destinations);
stop:
spin_unlock_bh(&svc->sched_lock);
ip_vs_scheduler_err(svc, "no destination available");
return NULL;
out:
svc->sched_data = &dest->n_list;
spin_unlock_bh(&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),
.init_service = ip_vs_rr_init_svc,
.add_dest = NULL,
.del_dest = ip_vs_rr_del_dest,
.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);
synchronize_rcu();
}
module_init(ip_vs_rr_init);
module_exit(ip_vs_rr_cleanup);
MODULE_LICENSE("GPL");
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