// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* IPVS: Round-Robin Scheduling module
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*
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* Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
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* Peter Kese <peter.kese@ijs.si>
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*
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* Fixes/Changes:
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* Wensong Zhang : changed the ip_vs_rr_schedule to return dest
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* Julian Anastasov : fixed the NULL pointer access bug in debugging
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* Wensong Zhang : changed some comestics things for debugging
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* Wensong Zhang : changed for the d-linked destination list
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* Wensong Zhang : added the ip_vs_rr_update_svc
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* Wensong Zhang : added any dest with weight=0 is quiesced
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*/
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#define KMSG_COMPONENT "IPVS"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <net/ip_vs.h>
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static int ip_vs_rr_init_svc(struct ip_vs_service *svc)
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{
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svc->sched_data = &svc->destinations;
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return 0;
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}
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static int ip_vs_rr_del_dest(struct ip_vs_service *svc, struct ip_vs_dest *dest)
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{
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struct list_head *p;
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spin_lock_bh(&svc->sched_lock);
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p = (struct list_head *) svc->sched_data;
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/* dest is already unlinked, so p->prev is not valid but
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* p->next is valid, use it to reach previous entry.
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*/
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if (p == &dest->n_list)
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svc->sched_data = p->next->prev;
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spin_unlock_bh(&svc->sched_lock);
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return 0;
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}
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/*
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* Round-Robin Scheduling
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*/
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static struct ip_vs_dest *
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ip_vs_rr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
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struct ip_vs_iphdr *iph)
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{
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struct list_head *p;
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struct ip_vs_dest *dest, *last;
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int pass = 0;
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IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
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spin_lock_bh(&svc->sched_lock);
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p = (struct list_head *) svc->sched_data;
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last = dest = list_entry(p, struct ip_vs_dest, n_list);
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do {
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list_for_each_entry_continue_rcu(dest,
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&svc->destinations,
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n_list) {
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if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
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atomic_read(&dest->weight) > 0)
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/* HIT */
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goto out;
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if (dest == last)
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goto stop;
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}
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pass++;
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/* Previous dest could be unlinked, do not loop forever.
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* If we stay at head there is no need for 2nd pass.
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*/
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} while (pass < 2 && p != &svc->destinations);
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stop:
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spin_unlock_bh(&svc->sched_lock);
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ip_vs_scheduler_err(svc, "no destination available");
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return NULL;
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out:
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svc->sched_data = &dest->n_list;
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spin_unlock_bh(&svc->sched_lock);
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IP_VS_DBG_BUF(6, "RR: server %s:%u "
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"activeconns %d refcnt %d weight %d\n",
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IP_VS_DBG_ADDR(dest->af, &dest->addr), ntohs(dest->port),
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atomic_read(&dest->activeconns),
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refcount_read(&dest->refcnt), atomic_read(&dest->weight));
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return dest;
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}
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static struct ip_vs_scheduler ip_vs_rr_scheduler = {
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.name = "rr", /* name */
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.refcnt = ATOMIC_INIT(0),
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.module = THIS_MODULE,
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.n_list = LIST_HEAD_INIT(ip_vs_rr_scheduler.n_list),
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.init_service = ip_vs_rr_init_svc,
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.add_dest = NULL,
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.del_dest = ip_vs_rr_del_dest,
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.schedule = ip_vs_rr_schedule,
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};
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static int __init ip_vs_rr_init(void)
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{
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return register_ip_vs_scheduler(&ip_vs_rr_scheduler);
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}
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static void __exit ip_vs_rr_cleanup(void)
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{
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unregister_ip_vs_scheduler(&ip_vs_rr_scheduler);
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synchronize_rcu();
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}
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module_init(ip_vs_rr_init);
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module_exit(ip_vs_rr_cleanup);
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MODULE_LICENSE("GPL");
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