Merge branch 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus
[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_done_svc(struct ip_vs_service *svc)
36 {
37         return 0;
38 }
39
40
41 static int ip_vs_rr_update_svc(struct ip_vs_service *svc)
42 {
43         svc->sched_data = &svc->destinations;
44         return 0;
45 }
46
47
48 /*
49  * Round-Robin Scheduling
50  */
51 static struct ip_vs_dest *
52 ip_vs_rr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
53 {
54         struct list_head *p, *q;
55         struct ip_vs_dest *dest;
56
57         IP_VS_DBG(6, "ip_vs_rr_schedule(): Scheduling...\n");
58
59         write_lock(&svc->sched_lock);
60         p = (struct list_head *)svc->sched_data;
61         p = p->next;
62         q = p;
63         do {
64                 /* skip list head */
65                 if (q == &svc->destinations) {
66                         q = q->next;
67                         continue;
68                 }
69
70                 dest = list_entry(q, struct ip_vs_dest, n_list);
71                 if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
72                     atomic_read(&dest->weight) > 0)
73                         /* HIT */
74                         goto out;
75                 q = q->next;
76         } while (q != p);
77         write_unlock(&svc->sched_lock);
78         return NULL;
79
80   out:
81         svc->sched_data = q;
82         write_unlock(&svc->sched_lock);
83         IP_VS_DBG(6, "RR: server %u.%u.%u.%u:%u "
84                   "activeconns %d refcnt %d weight %d\n",
85                   NIPQUAD(dest->addr), ntohs(dest->port),
86                   atomic_read(&dest->activeconns),
87                   atomic_read(&dest->refcnt), atomic_read(&dest->weight));
88
89         return dest;
90 }
91
92
93 static struct ip_vs_scheduler ip_vs_rr_scheduler = {
94         .name =                 "rr",                   /* name */
95         .refcnt =               ATOMIC_INIT(0),
96         .module =               THIS_MODULE,
97         .init_service =         ip_vs_rr_init_svc,
98         .done_service =         ip_vs_rr_done_svc,
99         .update_service =       ip_vs_rr_update_svc,
100         .schedule =             ip_vs_rr_schedule,
101 };
102
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
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");