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/spinlock.h>
24 #include <linux/interrupt.h>
25 #include <asm/string.h>
26 #include <linux/kmod.h>
27 #include <linux/sysctl.h>
28
29 #include <net/ip_vs.h>
30
31 /*
32 * IPVS scheduler list
33 */
34 static LIST_HEAD(ip_vs_schedulers);
35
36 /* lock for service table */
37 static DEFINE_RWLOCK(__ip_vs_sched_lock);
38
39
40 /*
41 * Bind a service with a scheduler
42 */
43 int ip_vs_bind_scheduler(struct ip_vs_service *svc,
44 struct ip_vs_scheduler *scheduler)
45 {
46 int ret;
47
48 if (svc == NULL) {
49 IP_VS_ERR("ip_vs_bind_scheduler(): svc arg NULL\n");
50 return -EINVAL;
51 }
52 if (scheduler == NULL) {
53 IP_VS_ERR("ip_vs_bind_scheduler(): scheduler arg NULL\n");
54 return -EINVAL;
55 }
56
57 svc->scheduler = scheduler;
58
59 if (scheduler->init_service) {
60 ret = scheduler->init_service(svc);
61 if (ret) {
62 IP_VS_ERR("ip_vs_bind_scheduler(): init error\n");
63 return ret;
64 }
65 }
66
67 return 0;
68 }
69
70
71 /*
72 * Unbind a service with its scheduler
73 */
74 int ip_vs_unbind_scheduler(struct ip_vs_service *svc)
75 {
76 struct ip_vs_scheduler *sched;
77
78 if (svc == NULL) {
79 IP_VS_ERR("ip_vs_unbind_scheduler(): svc arg NULL\n");
80 return -EINVAL;
81 }
82
83 sched = svc->scheduler;
84 if (sched == NULL) {
85 IP_VS_ERR("ip_vs_unbind_scheduler(): svc isn't bound\n");
86 return -EINVAL;
87 }
88
89 if (sched->done_service) {
90 if (sched->done_service(svc) != 0) {
91 IP_VS_ERR("ip_vs_unbind_scheduler(): done error\n");
92 return -EINVAL;
93 }
94 }
95
96 svc->scheduler = NULL;
97 return 0;
98 }
99
100
101 /*
102 * Get scheduler in the scheduler list by name
103 */
104 static struct ip_vs_scheduler *ip_vs_sched_getbyname(const char *sched_name)
105 {
106 struct ip_vs_scheduler *sched;
107
108 IP_VS_DBG(2, "ip_vs_sched_getbyname(): sched_name \"%s\"\n",
109 sched_name);
110
111 read_lock_bh(&__ip_vs_sched_lock);
112
113 list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
114 /*
115 * Test and get the modules atomically
116 */
117 if (sched->module && !try_module_get(sched->module)) {
118 /*
119 * This scheduler is just deleted
120 */
121 continue;
122 }
123 if (strcmp(sched_name, sched->name)==0) {
124 /* HIT */
125 read_unlock_bh(&__ip_vs_sched_lock);
126 return sched;
127 }
128 if (sched->module)
129 module_put(sched->module);
130 }
131
132 read_unlock_bh(&__ip_vs_sched_lock);
133 return NULL;
134 }
135
136
137 /*
138 * Lookup scheduler and try to load it if it doesn't exist
139 */
140 struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name)
141 {
142 struct ip_vs_scheduler *sched;
143
144 /*
145 * Search for the scheduler by sched_name
146 */
147 sched = ip_vs_sched_getbyname(sched_name);
148
149 /*
150 * If scheduler not found, load the module and search again
151 */
152 if (sched == NULL) {
153 request_module("ip_vs_%s", sched_name);
154 sched = ip_vs_sched_getbyname(sched_name);
155 }
156
157 return sched;
158 }
159
160 void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler)
161 {
162 if (scheduler->module)
163 module_put(scheduler->module);
164 }
165
166
167 /*
168 * Register a scheduler in the scheduler list
169 */
170 int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
171 {
172 struct ip_vs_scheduler *sched;
173
174 if (!scheduler) {
175 IP_VS_ERR("register_ip_vs_scheduler(): NULL arg\n");
176 return -EINVAL;
177 }
178
179 if (!scheduler->name) {
180 IP_VS_ERR("register_ip_vs_scheduler(): NULL scheduler_name\n");
181 return -EINVAL;
182 }
183
184 /* increase the module use count */
185 ip_vs_use_count_inc();
186
187 write_lock_bh(&__ip_vs_sched_lock);
188
189 if (scheduler->n_list.next != &scheduler->n_list) {
190 write_unlock_bh(&__ip_vs_sched_lock);
191 ip_vs_use_count_dec();
192 IP_VS_ERR("register_ip_vs_scheduler(): [%s] scheduler "
193 "already linked\n", scheduler->name);
194 return -EINVAL;
195 }
196
197 /*
198 * Make sure that the scheduler with this name doesn't exist
199 * in the scheduler list.
200 */
201 list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
202 if (strcmp(scheduler->name, sched->name) == 0) {
203 write_unlock_bh(&__ip_vs_sched_lock);
204 ip_vs_use_count_dec();
205 IP_VS_ERR("register_ip_vs_scheduler(): [%s] scheduler "
206 "already existed in the system\n",
207 scheduler->name);
208 return -EINVAL;
209 }
210 }
211 /*
212 * Add it into the d-linked scheduler list
213 */
214 list_add(&scheduler->n_list, &ip_vs_schedulers);
215 write_unlock_bh(&__ip_vs_sched_lock);
216
217 IP_VS_INFO("[%s] scheduler registered.\n", scheduler->name);
218
219 return 0;
220 }
221
222
223 /*
224 * Unregister a scheduler from the scheduler list
225 */
226 int unregister_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
227 {
228 if (!scheduler) {
229 IP_VS_ERR( "unregister_ip_vs_scheduler(): NULL arg\n");
230 return -EINVAL;
231 }
232
233 write_lock_bh(&__ip_vs_sched_lock);
234 if (scheduler->n_list.next == &scheduler->n_list) {
235 write_unlock_bh(&__ip_vs_sched_lock);
236 IP_VS_ERR("unregister_ip_vs_scheduler(): [%s] scheduler "
237 "is not in the list. failed\n", scheduler->name);
238 return -EINVAL;
239 }
240
241 /*
242 * Remove it from the d-linked scheduler list
243 */
244 list_del(&scheduler->n_list);
245 write_unlock_bh(&__ip_vs_sched_lock);
246
247 /* decrease the module use count */
248 ip_vs_use_count_dec();
249
250 IP_VS_INFO("[%s] scheduler unregistered.\n", scheduler->name);
251
252 return 0;
253 }
254
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