IPVS: Move IPVS to net/netfilter/ipvs
[linux-2.6.git] / net / netfilter / ipvs / ip_vs_sched.c
1 /*
2  * IPVS         An implementation of the IP virtual server support for the
3  *              LINUX operating system.  IPVS is now implemented as a module
4  *              over the Netfilter framework. IPVS can be used to build a
5  *              high-performance and highly available server based on a
6  *              cluster of servers.
7  *
8  * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
9  *              Peter Kese <peter.kese@ijs.si>
10  *
11  *              This program is free software; you can redistribute it and/or
12  *              modify it under the terms of the GNU General Public License
13  *              as published by the Free Software Foundation; either version
14  *              2 of the License, or (at your option) any later version.
15  *
16  * Changes:
17  *
18  */
19
20 #include <linux/module.h>
21 #include <linux/spinlock.h>
22 #include <linux/interrupt.h>
23 #include <asm/string.h>
24 #include <linux/kmod.h>
25 #include <linux/sysctl.h>
26
27 #include <net/ip_vs.h>
28
29 /*
30  *  IPVS scheduler list
31  */
32 static LIST_HEAD(ip_vs_schedulers);
33
34 /* lock for service table */
35 static DEFINE_RWLOCK(__ip_vs_sched_lock);
36
37
38 /*
39  *  Bind a service with a scheduler
40  */
41 int ip_vs_bind_scheduler(struct ip_vs_service *svc,
42                          struct ip_vs_scheduler *scheduler)
43 {
44         int ret;
45
46         if (svc == NULL) {
47                 IP_VS_ERR("ip_vs_bind_scheduler(): svc arg NULL\n");
48                 return -EINVAL;
49         }
50         if (scheduler == NULL) {
51                 IP_VS_ERR("ip_vs_bind_scheduler(): scheduler arg NULL\n");
52                 return -EINVAL;
53         }
54
55         svc->scheduler = scheduler;
56
57         if (scheduler->init_service) {
58                 ret = scheduler->init_service(svc);
59                 if (ret) {
60                         IP_VS_ERR("ip_vs_bind_scheduler(): init error\n");
61                         return ret;
62                 }
63         }
64
65         return 0;
66 }
67
68
69 /*
70  *  Unbind a service with its scheduler
71  */
72 int ip_vs_unbind_scheduler(struct ip_vs_service *svc)
73 {
74         struct ip_vs_scheduler *sched;
75
76         if (svc == NULL) {
77                 IP_VS_ERR("ip_vs_unbind_scheduler(): svc arg NULL\n");
78                 return -EINVAL;
79         }
80
81         sched = svc->scheduler;
82         if (sched == NULL) {
83                 IP_VS_ERR("ip_vs_unbind_scheduler(): svc isn't bound\n");
84                 return -EINVAL;
85         }
86
87         if (sched->done_service) {
88                 if (sched->done_service(svc) != 0) {
89                         IP_VS_ERR("ip_vs_unbind_scheduler(): done error\n");
90                         return -EINVAL;
91                 }
92         }
93
94         svc->scheduler = NULL;
95         return 0;
96 }
97
98
99 /*
100  *  Get scheduler in the scheduler list by name
101  */
102 static struct ip_vs_scheduler *ip_vs_sched_getbyname(const char *sched_name)
103 {
104         struct ip_vs_scheduler *sched;
105
106         IP_VS_DBG(2, "ip_vs_sched_getbyname(): sched_name \"%s\"\n",
107                   sched_name);
108
109         read_lock_bh(&__ip_vs_sched_lock);
110
111         list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
112                 /*
113                  * Test and get the modules atomically
114                  */
115                 if (sched->module && !try_module_get(sched->module)) {
116                         /*
117                          * This scheduler is just deleted
118                          */
119                         continue;
120                 }
121                 if (strcmp(sched_name, sched->name)==0) {
122                         /* HIT */
123                         read_unlock_bh(&__ip_vs_sched_lock);
124                         return sched;
125                 }
126                 if (sched->module)
127                         module_put(sched->module);
128         }
129
130         read_unlock_bh(&__ip_vs_sched_lock);
131         return NULL;
132 }
133
134
135 /*
136  *  Lookup scheduler and try to load it if it doesn't exist
137  */
138 struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name)
139 {
140         struct ip_vs_scheduler *sched;
141
142         /*
143          *  Search for the scheduler by sched_name
144          */
145         sched = ip_vs_sched_getbyname(sched_name);
146
147         /*
148          *  If scheduler not found, load the module and search again
149          */
150         if (sched == NULL) {
151                 request_module("ip_vs_%s", sched_name);
152                 sched = ip_vs_sched_getbyname(sched_name);
153         }
154
155         return sched;
156 }
157
158 void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler)
159 {
160         if (scheduler->module)
161                 module_put(scheduler->module);
162 }
163
164
165 /*
166  *  Register a scheduler in the scheduler list
167  */
168 int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
169 {
170         struct ip_vs_scheduler *sched;
171
172         if (!scheduler) {
173                 IP_VS_ERR("register_ip_vs_scheduler(): NULL arg\n");
174                 return -EINVAL;
175         }
176
177         if (!scheduler->name) {
178                 IP_VS_ERR("register_ip_vs_scheduler(): NULL scheduler_name\n");
179                 return -EINVAL;
180         }
181
182         /* increase the module use count */
183         ip_vs_use_count_inc();
184
185         write_lock_bh(&__ip_vs_sched_lock);
186
187         if (!list_empty(&scheduler->n_list)) {
188                 write_unlock_bh(&__ip_vs_sched_lock);
189                 ip_vs_use_count_dec();
190                 IP_VS_ERR("register_ip_vs_scheduler(): [%s] scheduler "
191                           "already linked\n", scheduler->name);
192                 return -EINVAL;
193         }
194
195         /*
196          *  Make sure that the scheduler with this name doesn't exist
197          *  in the scheduler list.
198          */
199         list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
200                 if (strcmp(scheduler->name, sched->name) == 0) {
201                         write_unlock_bh(&__ip_vs_sched_lock);
202                         ip_vs_use_count_dec();
203                         IP_VS_ERR("register_ip_vs_scheduler(): [%s] scheduler "
204                                         "already existed in the system\n",
205                                         scheduler->name);
206                         return -EINVAL;
207                 }
208         }
209         /*
210          *      Add it into the d-linked scheduler list
211          */
212         list_add(&scheduler->n_list, &ip_vs_schedulers);
213         write_unlock_bh(&__ip_vs_sched_lock);
214
215         IP_VS_INFO("[%s] scheduler registered.\n", scheduler->name);
216
217         return 0;
218 }
219
220
221 /*
222  *  Unregister a scheduler from the scheduler list
223  */
224 int unregister_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
225 {
226         if (!scheduler) {
227                 IP_VS_ERR( "unregister_ip_vs_scheduler(): NULL arg\n");
228                 return -EINVAL;
229         }
230
231         write_lock_bh(&__ip_vs_sched_lock);
232         if (list_empty(&scheduler->n_list)) {
233                 write_unlock_bh(&__ip_vs_sched_lock);
234                 IP_VS_ERR("unregister_ip_vs_scheduler(): [%s] scheduler "
235                           "is not in the list. failed\n", scheduler->name);
236                 return -EINVAL;
237         }
238
239         /*
240          *      Remove it from the d-linked scheduler list
241          */
242         list_del(&scheduler->n_list);
243         write_unlock_bh(&__ip_vs_sched_lock);
244
245         /* decrease the module use count */
246         ip_vs_use_count_dec();
247
248         IP_VS_INFO("[%s] scheduler unregistered.\n", scheduler->name);
249
250         return 0;
251 }