1 /*
2 * IPVS: Round-Robin Scheduling module
3 *
4 * Version: $Id: ip_vs_rr.c,v 1.8 2001/10/19 15:05:17 wensong Exp $
5 *
6 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
7 * Peter Kese <peter.kese@ijs.si>
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
13 *
14 * Fixes/Changes:
15 * Wensong Zhang : changed the ip_vs_rr_schedule to return dest
16 * Julian Anastasov : fixed the NULL pointer access bug in debugging
17 * Wensong Zhang : changed some comestics things for debugging
18 * Wensong Zhang : changed for the d-linked destination list
19 * Wensong Zhang : added the ip_vs_rr_update_svc
20 * Wensong Zhang : added any dest with weight=0 is quiesced
21 *
22 */
23
24 #include <linux/module.h>
25 #include <linux/kernel.h>
26
27 #include <net/ip_vs.h>
28
29
ip_vs_rr_init_svc(struct ip_vs_service * svc)30 static int ip_vs_rr_init_svc(struct ip_vs_service *svc)
31 {
32 svc->sched_data = &svc->destinations;
33 return 0;
34 }
35
36
ip_vs_rr_done_svc(struct ip_vs_service * svc)37 static int ip_vs_rr_done_svc(struct ip_vs_service *svc)
38 {
39 return 0;
40 }
41
42
ip_vs_rr_update_svc(struct ip_vs_service * svc)43 static int ip_vs_rr_update_svc(struct ip_vs_service *svc)
44 {
45 svc->sched_data = &svc->destinations;
46 return 0;
47 }
48
49
50 /*
51 * Round-Robin Scheduling
52 */
53 static struct ip_vs_dest *
ip_vs_rr_schedule(struct ip_vs_service * svc,struct iphdr * iph)54 ip_vs_rr_schedule(struct ip_vs_service *svc, struct iphdr *iph)
55 {
56 register struct list_head *p, *q;
57 struct ip_vs_dest *dest;
58
59 IP_VS_DBG(6, "ip_vs_rr_schedule(): Scheduling...\n");
60
61 write_lock(&svc->sched_lock);
62 p = (struct list_head *)svc->sched_data;
63 p = p->next;
64 q = p;
65 do {
66 if (q == &svc->destinations) {
67 q = q->next;
68 continue;
69 }
70 dest = list_entry(q, struct ip_vs_dest, n_list);
71 if (atomic_read(&dest->weight) > 0)
72 /* HIT */
73 goto out;
74 q = q->next;
75 } while (q != p);
76 write_unlock(&svc->sched_lock);
77 return NULL;
78
79 out:
80 svc->sched_data = q;
81 write_unlock(&svc->sched_lock);
82 IP_VS_DBG(6, "RR: server %u.%u.%u.%u:%u "
83 "activeconns %d refcnt %d weight %d\n",
84 NIPQUAD(dest->addr), ntohs(dest->port),
85 atomic_read(&dest->activeconns),
86 atomic_read(&dest->refcnt), atomic_read(&dest->weight));
87
88 return dest;
89 }
90
91
92 static struct ip_vs_scheduler ip_vs_rr_scheduler = {
93 {0}, /* n_list */
94 "rr", /* name */
95 ATOMIC_INIT(0), /* refcnt */
96 THIS_MODULE, /* this module */
97 ip_vs_rr_init_svc, /* service initializer */
98 ip_vs_rr_done_svc, /* service done */
99 ip_vs_rr_update_svc, /* service updater */
100 ip_vs_rr_schedule, /* select a server from the destination list */
101 };
102
ip_vs_rr_init(void)103 static int __init ip_vs_rr_init(void)
104 {
105 INIT_LIST_HEAD(&ip_vs_rr_scheduler.n_list);
106 return register_ip_vs_scheduler(&ip_vs_rr_scheduler);
107 }
108
ip_vs_rr_cleanup(void)109 static void __exit ip_vs_rr_cleanup(void)
110 {
111 unregister_ip_vs_scheduler(&ip_vs_rr_scheduler);
112 }
113
114 module_init(ip_vs_rr_init);
115 module_exit(ip_vs_rr_cleanup);
116 MODULE_LICENSE("GPL");
117