1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * IPVS: Weighted Fail Over module
4 *
5 * Authors: Kenny Mathis <kmathis@chokepoint.net>
6 *
7 * Changes:
8 * Kenny Mathis : added initial functionality based on weight
9 */
10
11 #define KMSG_COMPONENT "IPVS"
12 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
13
14 #include <linux/module.h>
15 #include <linux/kernel.h>
16
17 #include <net/ip_vs.h>
18
19 /* Weighted Fail Over Module */
20 static struct ip_vs_dest *
21 ip_vs_fo_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
22 struct ip_vs_iphdr *iph)
23 {
24 struct ip_vs_dest *dest, *hweight = NULL;
25 int hw = 0; /* Track highest weight */
26
27 IP_VS_DBG(6, "ip_vs_fo_schedule(): Scheduling...\n");
28
29 /* Basic failover functionality
30 * Find virtual server with highest weight and send it traffic
31 */
32 list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
33 if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
34 atomic_read(&dest->weight) > hw) {
35 hweight = dest;
36 hw = atomic_read(&dest->weight);
37 }
38 }
39
40 if (hweight) {
41 IP_VS_DBG_BUF(6, "FO: server %s:%u activeconns %d weight %d\n",
42 IP_VS_DBG_ADDR(hweight->af, &hweight->addr),
43 ntohs(hweight->port),
44 atomic_read(&hweight->activeconns),
45 atomic_read(&hweight->weight));
46 return hweight;
47 }
48
49 ip_vs_scheduler_err(svc, "no destination available");
50 return NULL;
51 }
52
53 static struct ip_vs_scheduler ip_vs_fo_scheduler = {
54 .name = "fo",
55 .refcnt = ATOMIC_INIT(0),
56 .module = THIS_MODULE,
57 .n_list = LIST_HEAD_INIT(ip_vs_fo_scheduler.n_list),
58 .schedule = ip_vs_fo_schedule,
59 };
60
61 static int __init ip_vs_fo_init(void)
62 {
63 return register_ip_vs_scheduler(&ip_vs_fo_scheduler);
64 }
65
66 static void __exit ip_vs_fo_cleanup(void)
67 {
68 unregister_ip_vs_scheduler(&ip_vs_fo_scheduler);
69 synchronize_rcu();
70 }
71
72 module_init(ip_vs_fo_init);
73 module_exit(ip_vs_fo_cleanup);
74 MODULE_LICENSE("GPL");
75 MODULE_DESCRIPTION("ipvs weighted failover scheduler");
76
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