Automatic merge of rsync://rsync.kernel.org/pub/scm/linux/kernel/git/torvalds/linux...
[linux-2.6] / net / ipv4 / 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  * Version:     $Id: ip_vs_sched.c,v 1.13 2003/05/10 03:05:23 wensong Exp $
9  *
10  * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
11  *              Peter Kese <peter.kese@ijs.si>
12  *
13  *              This program is free software; you can redistribute it and/or
14  *              modify it under the terms of the GNU General Public License
15  *              as published by the Free Software Foundation; either version
16  *              2 of the License, or (at your option) any later version.
17  *
18  * Changes:
19  *
20  */
21
22 #include <linux/module.h>
23 #include <linux/sched.h>
24 #include <linux/spinlock.h>
25 #include <asm/string.h>
26 #include <linux/kmod.h>
27
28 #include <net/ip_vs.h>
29
30 /*
31  *  IPVS scheduler list
32  */
33 static LIST_HEAD(ip_vs_schedulers);
34
35 /* lock for service table */
36 static DEFINE_RWLOCK(__ip_vs_sched_lock);
37
38
39 /*
40  *  Bind a service with a scheduler
41  */
42 int ip_vs_bind_scheduler(struct ip_vs_service *svc,
43                          struct ip_vs_scheduler *scheduler)
44 {
45         int ret;
46
47         if (svc == NULL) {
48                 IP_VS_ERR("ip_vs_bind_scheduler(): svc arg NULL\n");
49                 return -EINVAL;
50         }
51         if (scheduler == NULL) {
52                 IP_VS_ERR("ip_vs_bind_scheduler(): scheduler arg NULL\n");
53                 return -EINVAL;
54         }
55
56         svc->scheduler = scheduler;
57
58         if (scheduler->init_service) {
59                 ret = scheduler->init_service(svc);
60                 if (ret) {
61                         IP_VS_ERR("ip_vs_bind_scheduler(): init error\n");
62                         return ret;
63                 }
64         }
65
66         return 0;
67 }
68
69
70 /*
71  *  Unbind a service with its scheduler
72  */
73 int ip_vs_unbind_scheduler(struct ip_vs_service *svc)
74 {
75         struct ip_vs_scheduler *sched;
76
77         if (svc == NULL) {
78                 IP_VS_ERR("ip_vs_unbind_scheduler(): svc arg NULL\n");
79                 return -EINVAL;
80         }
81
82         sched = svc->scheduler;
83         if (sched == NULL) {
84                 IP_VS_ERR("ip_vs_unbind_scheduler(): svc isn't bound\n");
85                 return -EINVAL;
86         }
87
88         if (sched->done_service) {
89                 if (sched->done_service(svc) != 0) {
90                         IP_VS_ERR("ip_vs_unbind_scheduler(): done error\n");
91                         return -EINVAL;
92                 }
93         }
94
95         svc->scheduler = NULL;
96         return 0;
97 }
98
99
100 /*
101  *  Get scheduler in the scheduler list by name
102  */
103 static struct ip_vs_scheduler *ip_vs_sched_getbyname(const char *sched_name)
104 {
105         struct ip_vs_scheduler *sched;
106
107         IP_VS_DBG(2, "ip_vs_sched_getbyname(): sched_name \"%s\"\n",
108                   sched_name);
109
110         read_lock_bh(&__ip_vs_sched_lock);
111
112         list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
113                 /*
114                  * Test and get the modules atomically
115                  */
116                 if (sched->module && !try_module_get(sched->module)) {
117                         /*
118                          * This scheduler is just deleted
119                          */
120                         continue;
121                 }
122                 if (strcmp(sched_name, sched->name)==0) {
123                         /* HIT */
124                         read_unlock_bh(&__ip_vs_sched_lock);
125                         return sched;
126                 }
127                 if (sched->module)
128                         module_put(sched->module);
129         }
130
131         read_unlock_bh(&__ip_vs_sched_lock);
132         return NULL;
133 }
134
135
136 /*
137  *  Lookup scheduler and try to load it if it doesn't exist
138  */
139 struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name)
140 {
141         struct ip_vs_scheduler *sched;
142
143         /*
144          *  Search for the scheduler by sched_name
145          */
146         sched = ip_vs_sched_getbyname(sched_name);
147
148         /*
149          *  If scheduler not found, load the module and search again
150          */
151         if (sched == NULL) {
152                 request_module("ip_vs_%s", sched_name);
153                 sched = ip_vs_sched_getbyname(sched_name);
154         }
155
156         return sched;
157 }
158
159 void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler)
160 {
161         if (scheduler->module)
162                 module_put(scheduler->module);
163 }
164
165
166 /*
167  *  Register a scheduler in the scheduler list
168  */
169 int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
170 {
171         struct ip_vs_scheduler *sched;
172
173         if (!scheduler) {
174                 IP_VS_ERR("register_ip_vs_scheduler(): NULL arg\n");
175                 return -EINVAL;
176         }
177
178         if (!scheduler->name) {
179                 IP_VS_ERR("register_ip_vs_scheduler(): NULL scheduler_name\n");
180                 return -EINVAL;
181         }
182
183         /* increase the module use count */
184         ip_vs_use_count_inc();
185
186         /*
187          *  Make sure that the scheduler with this name doesn't exist
188          *  in the scheduler list.
189          */
190         sched = ip_vs_sched_getbyname(scheduler->name);
191         if (sched) {
192                 ip_vs_scheduler_put(sched);
193                 ip_vs_use_count_dec();
194                 IP_VS_ERR("register_ip_vs_scheduler(): [%s] scheduler "
195                           "already existed in the system\n", scheduler->name);
196                 return -EINVAL;
197         }
198
199         write_lock_bh(&__ip_vs_sched_lock);
200
201         if (scheduler->n_list.next != &scheduler->n_list) {
202                 write_unlock_bh(&__ip_vs_sched_lock);
203                 ip_vs_use_count_dec();
204                 IP_VS_ERR("register_ip_vs_scheduler(): [%s] scheduler "
205                           "already linked\n", 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 (scheduler->n_list.next == &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 }