Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
[linux-2.6] / net / ipv4 / ipvs / ip_vs_rr.c
1 /*
2  * IPVS:        Round-Robin Scheduling module
3  *
4  * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
5  *              Peter Kese <peter.kese@ijs.si>
6  *
7  *              This program is free software; you can redistribute it and/or
8  *              modify it under the terms of the GNU General Public License
9  *              as published by the Free Software Foundation; either version
10  *              2 of the License, or (at your option) any later version.
11  *
12  * Fixes/Changes:
13  *     Wensong Zhang            :     changed the ip_vs_rr_schedule to return dest
14  *     Julian Anastasov         :     fixed the NULL pointer access bug in debugging
15  *     Wensong Zhang            :     changed some comestics things for debugging
16  *     Wensong Zhang            :     changed for the d-linked destination list
17  *     Wensong Zhang            :     added the ip_vs_rr_update_svc
18  *     Wensong Zhang            :     added any dest with weight=0 is quiesced
19  *
20  */
21
22 #include <linux/module.h>
23 #include <linux/kernel.h>
24
25 #include <net/ip_vs.h>
26
27
28 static int ip_vs_rr_init_svc(struct ip_vs_service *svc)
29 {
30         svc->sched_data = &svc->destinations;
31         return 0;
32 }
33
34
35 static int ip_vs_rr_update_svc(struct ip_vs_service *svc)
36 {
37         svc->sched_data = &svc->destinations;
38         return 0;
39 }
40
41
42 /*
43  * Round-Robin Scheduling
44  */
45 static struct ip_vs_dest *
46 ip_vs_rr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
47 {
48         struct list_head *p, *q;
49         struct ip_vs_dest *dest;
50
51         IP_VS_DBG(6, "ip_vs_rr_schedule(): Scheduling...\n");
52
53         write_lock(&svc->sched_lock);
54         p = (struct list_head *)svc->sched_data;
55         p = p->next;
56         q = p;
57         do {
58                 /* skip list head */
59                 if (q == &svc->destinations) {
60                         q = q->next;
61                         continue;
62                 }
63
64                 dest = list_entry(q, struct ip_vs_dest, n_list);
65                 if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
66                     atomic_read(&dest->weight) > 0)
67                         /* HIT */
68                         goto out;
69                 q = q->next;
70         } while (q != p);
71         write_unlock(&svc->sched_lock);
72         return NULL;
73
74   out:
75         svc->sched_data = q;
76         write_unlock(&svc->sched_lock);
77         IP_VS_DBG(6, "RR: server %u.%u.%u.%u:%u "
78                   "activeconns %d refcnt %d weight %d\n",
79                   NIPQUAD(dest->addr), ntohs(dest->port),
80                   atomic_read(&dest->activeconns),
81                   atomic_read(&dest->refcnt), atomic_read(&dest->weight));
82
83         return dest;
84 }
85
86
87 static struct ip_vs_scheduler ip_vs_rr_scheduler = {
88         .name =                 "rr",                   /* name */
89         .refcnt =               ATOMIC_INIT(0),
90         .module =               THIS_MODULE,
91         .n_list =               LIST_HEAD_INIT(ip_vs_rr_scheduler.n_list),
92         .init_service =         ip_vs_rr_init_svc,
93         .update_service =       ip_vs_rr_update_svc,
94         .schedule =             ip_vs_rr_schedule,
95 };
96
97 static int __init ip_vs_rr_init(void)
98 {
99         return register_ip_vs_scheduler(&ip_vs_rr_scheduler);
100 }
101
102 static void __exit ip_vs_rr_cleanup(void)
103 {
104         unregister_ip_vs_scheduler(&ip_vs_rr_scheduler);
105 }
106
107 module_init(ip_vs_rr_init);
108 module_exit(ip_vs_rr_cleanup);
109 MODULE_LICENSE("GPL");