LXR linux/net/netfilter/ipvs/ip_vs

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * IPVS:        Overflow-Connection Scheduling module
   4 *
   5 * Authors:     Raducu Deaconu <rhadoo_io@yahoo.com>
   6 *
   7 * Scheduler implements "overflow" loadbalancing according to number of active
   8 * connections , will keep all connections to the node with the highest weight
   9 * and overflow to the next node if the number of connections exceeds the node's
  10 * weight.
  11 * Note that this scheduler might not be suitable for UDP because it only uses
  12 * active connections
  13 */
  14
  15#define KMSG_COMPONENT "IPVS"
  16#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  17
  18#include <linux/module.h>
  19#include <linux/kernel.h>
  20
  21#include <net/ip_vs.h>
  22
  23/* OVF Connection scheduling  */
  24static struct ip_vs_dest *
  25ip_vs_ovf_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
  26                   struct ip_vs_iphdr *iph)
  27{
  28        struct ip_vs_dest *dest, *h = NULL;
  29        int hw = 0, w;
  30
  31        IP_VS_DBG(6, "ip_vs_ovf_schedule(): Scheduling...\n");
  32        /* select the node with highest weight, go to next in line if active
  33        * connections exceed weight
  34        */
  35        list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
  36                w = atomic_read(&dest->weight);
  37                if ((dest->flags & IP_VS_DEST_F_OVERLOAD) ||
  38                    atomic_read(&dest->activeconns) > w ||
  39                    w == 0)
  40                        continue;
  41                if (!h || w > hw) {
  42                        h = dest;
  43                        hw = w;
  44                }
  45        }
  46
  47        if (h) {
  48                IP_VS_DBG_BUF(6, "OVF: server %s:%u active %d w %d\n",
  49                              IP_VS_DBG_ADDR(h->af, &h->addr),
  50                              ntohs(h->port),
  51                              atomic_read(&h->activeconns),
  52                              atomic_read(&h->weight));
  53                return h;
  54        }
  55
  56        ip_vs_scheduler_err(svc, "no destination available");
  57        return NULL;
  58}
  59
  60static struct ip_vs_scheduler ip_vs_ovf_scheduler = {
  61        .name =                 "ovf",
  62        .refcnt =               ATOMIC_INIT(0),
  63        .module =               THIS_MODULE,
  64        .n_list =               LIST_HEAD_INIT(ip_vs_ovf_scheduler.n_list),
  65        .schedule =             ip_vs_ovf_schedule,
  66};
  67
  68static int __init ip_vs_ovf_init(void)
  69{
  70        return register_ip_vs_scheduler(&ip_vs_ovf_scheduler);
  71}
  72
  73static void __exit ip_vs_ovf_cleanup(void)
  74{
  75        unregister_ip_vs_scheduler(&ip_vs_ovf_scheduler);
  76        synchronize_rcu();
  77}
  78
  79module_init(ip_vs_ovf_init);
  80module_exit(ip_vs_ovf_cleanup);
  81MODULE_LICENSE("GPL");
  82