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1da177e4 LT |
1 | /* |
2 | * IPVS: Round-Robin Scheduling module | |
3 | * | |
1da177e4 LT |
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 | ||
9aada7ac HE |
22 | #define KMSG_COMPONENT "IPVS" |
23 | #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt | |
24 | ||
1da177e4 LT |
25 | #include <linux/module.h> |
26 | #include <linux/kernel.h> | |
27 | ||
28 | #include <net/ip_vs.h> | |
29 | ||
30 | ||
31 | static int ip_vs_rr_init_svc(struct ip_vs_service *svc) | |
32 | { | |
33 | svc->sched_data = &svc->destinations; | |
34 | return 0; | |
35 | } | |
36 | ||
37 | ||
c0d0c0a1 | 38 | static int ip_vs_rr_del_dest(struct ip_vs_service *svc, struct ip_vs_dest *dest) |
1da177e4 | 39 | { |
c0d0c0a1 JA |
40 | struct list_head *p; |
41 | ||
ba3a3ce1 | 42 | spin_lock_bh(&svc->sched_lock); |
c0d0c0a1 JA |
43 | p = (struct list_head *) svc->sched_data; |
44 | /* dest is already unlinked, so p->prev is not valid but | |
45 | * p->next is valid, use it to reach previous entry. | |
46 | */ | |
47 | if (p == &dest->n_list) | |
48 | svc->sched_data = p->next->prev; | |
ba3a3ce1 | 49 | spin_unlock_bh(&svc->sched_lock); |
1da177e4 LT |
50 | return 0; |
51 | } | |
52 | ||
53 | ||
54 | /* | |
55 | * Round-Robin Scheduling | |
56 | */ | |
57 | static struct ip_vs_dest * | |
bba54de5 JA |
58 | ip_vs_rr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb, |
59 | struct ip_vs_iphdr *iph) | |
1da177e4 | 60 | { |
c0d0c0a1 JA |
61 | struct list_head *p; |
62 | struct ip_vs_dest *dest, *last; | |
63 | int pass = 0; | |
1da177e4 | 64 | |
1e3e238e | 65 | IP_VS_DBG(6, "%s(): Scheduling...\n", __func__); |
1da177e4 | 66 | |
ac69269a | 67 | spin_lock_bh(&svc->sched_lock); |
c0d0c0a1 JA |
68 | p = (struct list_head *) svc->sched_data; |
69 | last = dest = list_entry(p, struct ip_vs_dest, n_list); | |
70 | ||
1da177e4 | 71 | do { |
c0d0c0a1 JA |
72 | list_for_each_entry_continue_rcu(dest, |
73 | &svc->destinations, | |
74 | n_list) { | |
75 | if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && | |
76 | atomic_read(&dest->weight) > 0) | |
77 | /* HIT */ | |
78 | goto out; | |
79 | if (dest == last) | |
80 | goto stop; | |
1da177e4 | 81 | } |
c0d0c0a1 JA |
82 | pass++; |
83 | /* Previous dest could be unlinked, do not loop forever. | |
84 | * If we stay at head there is no need for 2nd pass. | |
85 | */ | |
86 | } while (pass < 2 && p != &svc->destinations); | |
e905a9ed | 87 | |
c0d0c0a1 | 88 | stop: |
ac69269a | 89 | spin_unlock_bh(&svc->sched_lock); |
41ac51ee | 90 | ip_vs_scheduler_err(svc, "no destination available"); |
1da177e4 LT |
91 | return NULL; |
92 | ||
93 | out: | |
c0d0c0a1 | 94 | svc->sched_data = &dest->n_list; |
ac69269a | 95 | spin_unlock_bh(&svc->sched_lock); |
b14198f6 JV |
96 | IP_VS_DBG_BUF(6, "RR: server %s:%u " |
97 | "activeconns %d refcnt %d weight %d\n", | |
4d316f3f | 98 | IP_VS_DBG_ADDR(dest->af, &dest->addr), ntohs(dest->port), |
b14198f6 JV |
99 | atomic_read(&dest->activeconns), |
100 | atomic_read(&dest->refcnt), atomic_read(&dest->weight)); | |
1da177e4 LT |
101 | |
102 | return dest; | |
103 | } | |
104 | ||
105 | ||
106 | static struct ip_vs_scheduler ip_vs_rr_scheduler = { | |
107 | .name = "rr", /* name */ | |
108 | .refcnt = ATOMIC_INIT(0), | |
109 | .module = THIS_MODULE, | |
d149ccc9 | 110 | .n_list = LIST_HEAD_INIT(ip_vs_rr_scheduler.n_list), |
1da177e4 | 111 | .init_service = ip_vs_rr_init_svc, |
c0d0c0a1 JA |
112 | .add_dest = NULL, |
113 | .del_dest = ip_vs_rr_del_dest, | |
1da177e4 LT |
114 | .schedule = ip_vs_rr_schedule, |
115 | }; | |
116 | ||
117 | static int __init ip_vs_rr_init(void) | |
118 | { | |
1da177e4 LT |
119 | return register_ip_vs_scheduler(&ip_vs_rr_scheduler); |
120 | } | |
121 | ||
122 | static void __exit ip_vs_rr_cleanup(void) | |
123 | { | |
124 | unregister_ip_vs_scheduler(&ip_vs_rr_scheduler); | |
ceec4c38 | 125 | synchronize_rcu(); |
1da177e4 LT |
126 | } |
127 | ||
128 | module_init(ip_vs_rr_init); | |
129 | module_exit(ip_vs_rr_cleanup); | |
130 | MODULE_LICENSE("GPL"); |