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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(dest->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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