[net-next-2.6.git] / net / ipv4 / ipvs / ip_vs_rr.c

/*
 * 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(6, "RR: server %u.%u.%u.%u:%u "
		  "activeconns %d refcnt %d weight %d\n",
		  NIPQUAD(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,
	.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");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* IPVS: Round-Robin Scheduling module
	3	*
1da177e4 LT	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
1da177e4 LT	35	static int ip_vs_rr_update_svc(struct ip_vs_service *svc)
	36	{
	37	svc->sched_data = &svc->destinations;
	38	return 0;
	39	}
	40
	41
	42	/*
	43	* Round-Robin Scheduling
	44	*/
	45	static struct ip_vs_dest *
	46	ip_vs_rr_schedule(struct ip_vs_service svc, const struct sk_buff skb)
	47	{
	48	struct list_head p, q;
	49	struct ip_vs_dest *dest;
	50
	51	IP_VS_DBG(6, "ip_vs_rr_schedule(): Scheduling...\n");
	52
	53	write_lock(&svc->sched_lock);
	54	p = (struct list_head *)svc->sched_data;
	55	p = p->next;
	56	q = p;
	57	do {
	58	/* skip list head */
	59	if (q == &svc->destinations) {
	60	q = q->next;
	61	continue;
	62	}
e905a9ed	63
1da177e4 LT	64	dest = list_entry(q, struct ip_vs_dest, n_list);
	65	if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
	66	atomic_read(&dest->weight) > 0)
	67	/* HIT */
	68	goto out;
	69	q = q->next;
	70	} while (q != p);
	71	write_unlock(&svc->sched_lock);
	72	return NULL;
	73
	74	out:
	75	svc->sched_data = q;
	76	write_unlock(&svc->sched_lock);
	77	IP_VS_DBG(6, "RR: server %u.%u.%u.%u:%u "
	78	"activeconns %d refcnt %d weight %d\n",
	79	NIPQUAD(dest->addr), ntohs(dest->port),
	80	atomic_read(&dest->activeconns),
	81	atomic_read(&dest->refcnt), atomic_read(&dest->weight));
	82
	83	return dest;
	84	}
	85
	86
	87	static struct ip_vs_scheduler ip_vs_rr_scheduler = {
	88	.name = "rr", /* name */
	89	.refcnt = ATOMIC_INIT(0),
	90	.module = THIS_MODULE,
d149ccc9	91	.n_list = LIST_HEAD_INIT(ip_vs_rr_scheduler.n_list),
1da177e4	92	.init_service = ip_vs_rr_init_svc,
1da177e4 LT	93	.update_service = ip_vs_rr_update_svc,
	94	.schedule = ip_vs_rr_schedule,
	95	};
	96
	97	static int __init ip_vs_rr_init(void)
	98	{
1da177e4 LT	99	return register_ip_vs_scheduler(&ip_vs_rr_scheduler);
	100	}
	101
	102	static void __exit ip_vs_rr_cleanup(void)
	103	{
	104	unregister_ip_vs_scheduler(&ip_vs_rr_scheduler);
	105	}
	106
	107	module_init(ip_vs_rr_init);
	108	module_exit(ip_vs_rr_cleanup);
	109	MODULE_LICENSE("GPL");