1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * IPVS An implementation of the IP virtual server support for the
4 * LINUX operating system. IPVS is now implemented as a module
5 * over the Netfilter framework. IPVS can be used to build a
6 * high-performance and highly available server based on a
7 * cluster of servers.
8 *
9 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
10 * Peter Kese <peter.kese@ijs.si>
11 *
12 * Changes:
13 */
14
15#define KMSG_COMPONENT "IPVS"
16#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
17
18#include <linux/module.h>
19#include <linux/spinlock.h>
20#include <linux/interrupt.h>
21#include <asm/string.h>
22#include <linux/kmod.h>
23#include <linux/sysctl.h>
24
25#include <net/ip_vs.h>
26
27EXPORT_SYMBOL(ip_vs_scheduler_err);
28/*
29 * IPVS scheduler list
30 */
31static LIST_HEAD(ip_vs_schedulers);
32
33/* semaphore for schedulers */
34static DEFINE_MUTEX(ip_vs_sched_mutex);
35
36
37/*
38 * Bind a service with a scheduler
39 */
40int ip_vs_bind_scheduler(struct ip_vs_service *svc,
41 struct ip_vs_scheduler *scheduler)
42{
43 int ret;
44
45 if (scheduler->init_service) {
46 ret = scheduler->init_service(svc);
47 if (ret) {
48 pr_err("%s(): init error\n", __func__);
49 return ret;
50 }
51 }
52 rcu_assign_pointer(svc->scheduler, scheduler);
53 return 0;
54}
55
56
57/*
58 * Unbind a service with its scheduler
59 */
60void ip_vs_unbind_scheduler(struct ip_vs_service *svc,
61 struct ip_vs_scheduler *sched)
62{
63 struct ip_vs_scheduler *cur_sched;
64
65 cur_sched = rcu_dereference_protected(svc->scheduler, 1);
66 /* This check proves that old 'sched' was installed */
67 if (!cur_sched)
68 return;
69
70 if (sched->done_service)
71 sched->done_service(svc);
72 /* svc->scheduler can be set to NULL only by caller */
73}
74
75
76/*
77 * Get scheduler in the scheduler list by name
78 */
79static struct ip_vs_scheduler *ip_vs_sched_getbyname(const char *sched_name)
80{
81 struct ip_vs_scheduler *sched;
82
83 IP_VS_DBG(2, "%s(): sched_name \"%s\"\n", __func__, sched_name);
84
85 mutex_lock(&ip_vs_sched_mutex);
86
87 list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
88 /*
89 * Test and get the modules atomically
90 */
91 if (sched->module && !try_module_get(module: sched->module)) {
92 /*
93 * This scheduler is just deleted
94 */
95 continue;
96 }
97 if (strcmp(sched_name, sched->name)==0) {
98 /* HIT */
99 mutex_unlock(lock: &ip_vs_sched_mutex);
100 return sched;
101 }
102 module_put(module: sched->module);
103 }
104
105 mutex_unlock(lock: &ip_vs_sched_mutex);
106 return NULL;
107}
108
109
110/*
111 * Lookup scheduler and try to load it if it doesn't exist
112 */
113struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name)
114{
115 struct ip_vs_scheduler *sched;
116
117 /*
118 * Search for the scheduler by sched_name
119 */
120 sched = ip_vs_sched_getbyname(sched_name);
121
122 /*
123 * If scheduler not found, load the module and search again
124 */
125 if (sched == NULL) {
126 request_module("ip_vs_%s", sched_name);
127 sched = ip_vs_sched_getbyname(sched_name);
128 }
129
130 return sched;
131}
132
133void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler)
134{
135 if (scheduler)
136 module_put(module: scheduler->module);
137}
138
139/*
140 * Common error output helper for schedulers
141 */
142
143void ip_vs_scheduler_err(struct ip_vs_service *svc, const char *msg)
144{
145 struct ip_vs_scheduler *sched = rcu_dereference(svc->scheduler);
146 char *sched_name = sched ? sched->name : "none";
147
148 if (svc->fwmark) {
149 IP_VS_ERR_RL("%s: FWM %u 0x%08X - %s\n",
150 sched_name, svc->fwmark, svc->fwmark, msg);
151#ifdef CONFIG_IP_VS_IPV6
152 } else if (svc->af == AF_INET6) {
153 IP_VS_ERR_RL("%s: %s [%pI6c]:%d - %s\n",
154 sched_name, ip_vs_proto_name(svc->protocol),
155 &svc->addr.in6, ntohs(svc->port), msg);
156#endif
157 } else {
158 IP_VS_ERR_RL("%s: %s %pI4:%d - %s\n",
159 sched_name, ip_vs_proto_name(svc->protocol),
160 &svc->addr.ip, ntohs(svc->port), msg);
161 }
162}
163
164/*
165 * Register a scheduler in the scheduler list
166 */
167int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
168{
169 struct ip_vs_scheduler *sched;
170
171 if (!scheduler) {
172 pr_err("%s(): NULL arg\n", __func__);
173 return -EINVAL;
174 }
175
176 if (!scheduler->name) {
177 pr_err("%s(): NULL scheduler_name\n", __func__);
178 return -EINVAL;
179 }
180
181 /* increase the module use count */
182 if (!ip_vs_use_count_inc())
183 return -ENOENT;
184
185 mutex_lock(&ip_vs_sched_mutex);
186
187 if (!list_empty(head: &scheduler->n_list)) {
188 mutex_unlock(lock: &ip_vs_sched_mutex);
189 ip_vs_use_count_dec();
190 pr_err("%s(): [%s] scheduler already linked\n",
191 __func__, 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 mutex_unlock(lock: &ip_vs_sched_mutex);
202 ip_vs_use_count_dec();
203 pr_err("%s(): [%s] scheduler already existed "
204 "in the system\n", __func__, scheduler->name);
205 return -EINVAL;
206 }
207 }
208 /*
209 * Add it into the d-linked scheduler list
210 */
211 list_add(new: &scheduler->n_list, head: &ip_vs_schedulers);
212 mutex_unlock(lock: &ip_vs_sched_mutex);
213
214 pr_info("[%s] scheduler registered.\n", scheduler->name);
215
216 return 0;
217}
218
219
220/*
221 * Unregister a scheduler from the scheduler list
222 */
223int unregister_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
224{
225 if (!scheduler) {
226 pr_err("%s(): NULL arg\n", __func__);
227 return -EINVAL;
228 }
229
230 mutex_lock(&ip_vs_sched_mutex);
231 if (list_empty(head: &scheduler->n_list)) {
232 mutex_unlock(lock: &ip_vs_sched_mutex);
233 pr_err("%s(): [%s] scheduler is not in the list. failed\n",
234 __func__, scheduler->name);
235 return -EINVAL;
236 }
237
238 /*
239 * Remove it from the d-linked scheduler list
240 */
241 list_del(entry: &scheduler->n_list);
242 mutex_unlock(lock: &ip_vs_sched_mutex);
243
244 /* decrease the module use count */
245 ip_vs_use_count_dec();
246
247 pr_info("[%s] scheduler unregistered.\n", scheduler->name);
248
249 return 0;
250}
251

source code of linux/net/netfilter/ipvs/ip_vs_sched.c