// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* IPVS: Least-Connection Scheduling module
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*
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* Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
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*
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* Changes:
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* Wensong Zhang : added the ip_vs_lc_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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/*
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* Least Connection scheduling
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*/
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static struct ip_vs_dest *
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ip_vs_lc_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 ip_vs_dest *dest, *least = NULL;
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unsigned int loh = 0, doh;
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IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
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/*
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* Simply select the server with the least number of
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* (activeconns<<5) + inactconns
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* Except whose weight is equal to zero.
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* If the weight is equal to zero, it means that the server is
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* quiesced, the existing connections to the server still get
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* served, but no new connection is assigned to the server.
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*/
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list_for_each_entry_rcu(dest, &svc->destinations, 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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continue;
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doh = ip_vs_dest_conn_overhead(dest);
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if (!least || doh < loh) {
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least = dest;
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loh = doh;
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}
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}
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if (!least)
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ip_vs_scheduler_err(svc, "no destination available");
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else
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IP_VS_DBG_BUF(6, "LC: server %s:%u activeconns %d "
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"inactconns %d\n",
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IP_VS_DBG_ADDR(least->af, &least->addr),
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ntohs(least->port),
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atomic_read(&least->activeconns),
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atomic_read(&least->inactconns));
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return least;
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}
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static struct ip_vs_scheduler ip_vs_lc_scheduler = {
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.name = "lc",
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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_lc_scheduler.n_list),
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.schedule = ip_vs_lc_schedule,
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};
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static int __init ip_vs_lc_init(void)
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{
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return register_ip_vs_scheduler(&ip_vs_lc_scheduler) ;
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}
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static void __exit ip_vs_lc_cleanup(void)
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{
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unregister_ip_vs_scheduler(&ip_vs_lc_scheduler);
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synchronize_rcu();
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}
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module_init(ip_vs_lc_init);
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module_exit(ip_vs_lc_cleanup);
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MODULE_LICENSE("GPL");
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