[mirror_ubuntu-zesty-kernel.git] / net / netfilter / 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
 *
 */

#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 list_head *p;
	struct ip_vs_dest *dest, *last;
	int pass = 0;

	IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);

	spin_lock(&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(&svc->sched_lock);
	ip_vs_scheduler_err(svc, "no destination available");
	return NULL;

  out:
	svc->sched_data = &dest->n_list;
	spin_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),
	.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");
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
9aada7ac HE	22	#define KMSG_COMPONENT "IPVS"
	23	#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
	24
1da177e4 LT	25	#include <linux/module.h>
	26	#include <linux/kernel.h>
	27
	28	#include <net/ip_vs.h>
	29
	30
	31	static int ip_vs_rr_init_svc(struct ip_vs_service *svc)
	32	{
	33	svc->sched_data = &svc->destinations;
	34	return 0;
	35	}
	36
	37
c0d0c0a1	38	static int ip_vs_rr_del_dest(struct ip_vs_service svc, struct ip_vs_dest dest)
1da177e4	39	{
c0d0c0a1 JA	40	struct list_head *p;
c0d0c0a1 JA	41
ba3a3ce1	42	spin_lock_bh(&svc->sched_lock);
c0d0c0a1 JA	43	p = (struct list_head *) svc->sched_data;
	44	/* dest is already unlinked, so p->prev is not valid but
	45	* p->next is valid, use it to reach previous entry.
	46	*/
	47	if (p == &dest->n_list)
	48	svc->sched_data = p->next->prev;
ba3a3ce1	49	spin_unlock_bh(&svc->sched_lock);
1da177e4 LT	50	return 0;
	51	}
	52
	53
	54	/*
	55	* Round-Robin Scheduling
	56	*/
	57	static struct ip_vs_dest *
	58	ip_vs_rr_schedule(struct ip_vs_service svc, const struct sk_buff skb)
	59	{
c0d0c0a1 JA	60	struct list_head *p;
	61	struct ip_vs_dest dest, last;
	62	int pass = 0;
1da177e4	63
1e3e238e	64	IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
1da177e4	65
ba3a3ce1	66	spin_lock(&svc->sched_lock);
c0d0c0a1 JA	67	p = (struct list_head *) svc->sched_data;
	68	last = dest = list_entry(p, struct ip_vs_dest, n_list);
	69
1da177e4	70	do {
c0d0c0a1 JA	71	list_for_each_entry_continue_rcu(dest,
	72	&svc->destinations,
	73	n_list) {
	74	if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
	75	atomic_read(&dest->weight) > 0)
	76	/* HIT */
	77	goto out;
	78	if (dest == last)
	79	goto stop;
1da177e4	80	}
c0d0c0a1 JA	81	pass++;
	82	/* Previous dest could be unlinked, do not loop forever.
	83	* If we stay at head there is no need for 2nd pass.
	84	*/
	85	} while (pass < 2 && p != &svc->destinations);
e905a9ed	86
c0d0c0a1	87	stop:
ba3a3ce1	88	spin_unlock(&svc->sched_lock);
41ac51ee	89	ip_vs_scheduler_err(svc, "no destination available");
1da177e4 LT	90	return NULL;
	91
	92	out:
c0d0c0a1	93	svc->sched_data = &dest->n_list;
ba3a3ce1	94	spin_unlock(&svc->sched_lock);
b14198f6 JV	95	IP_VS_DBG_BUF(6, "RR: server %s:%u "
	96	"activeconns %d refcnt %d weight %d\n",
	97	IP_VS_DBG_ADDR(svc->af, &dest->addr), ntohs(dest->port),
	98	atomic_read(&dest->activeconns),
	99	atomic_read(&dest->refcnt), atomic_read(&dest->weight));
1da177e4 LT	100
	101	return dest;
	102	}
	103
	104
	105	static struct ip_vs_scheduler ip_vs_rr_scheduler = {
	106	.name = "rr", /* name */
	107	.refcnt = ATOMIC_INIT(0),
	108	.module = THIS_MODULE,
d149ccc9	109	.n_list = LIST_HEAD_INIT(ip_vs_rr_scheduler.n_list),
1da177e4	110	.init_service = ip_vs_rr_init_svc,
c0d0c0a1 JA	111	.add_dest = NULL,
c0d0c0a1 JA	112	.del_dest = ip_vs_rr_del_dest,
1da177e4 LT	113	.schedule = ip_vs_rr_schedule,
	114	};
	115
	116	static int __init ip_vs_rr_init(void)
	117	{
1da177e4 LT	118	return register_ip_vs_scheduler(&ip_vs_rr_scheduler);
	119	}
	120
	121	static void __exit ip_vs_rr_cleanup(void)
	122	{
	123	unregister_ip_vs_scheduler(&ip_vs_rr_scheduler);
ceec4c38	124	synchronize_rcu();
1da177e4 LT	125	}
	126
	127	module_init(ip_vs_rr_init);
	128	module_exit(ip_vs_rr_cleanup);
	129	MODULE_LICENSE("GPL");