ip_vs_sched.c

  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 pr_fmt(fmt) "IPVS: " fmt
 16
 17#include <linux/module.h>
 18#include <linux/spinlock.h>
 19#include <linux/interrupt.h>
 20#include <asm/string.h>
 21#include <linux/kmod.h>
 22#include <linux/sysctl.h>
 23
 24#include <net/ip_vs.h>
 25
 26EXPORT_SYMBOL(ip_vs_scheduler_err);
 27/*
 28 *  IPVS scheduler list
 29 */
 30static LIST_HEAD(ip_vs_schedulers);
 31
 32/* semaphore for schedulers */
 33static DEFINE_MUTEX(ip_vs_sched_mutex);
 34
 35
 36/*
 37 *  Bind a service with a scheduler
 38 */
 39int ip_vs_bind_scheduler(struct ip_vs_service *svc,
 40			 struct ip_vs_scheduler *scheduler)
 41{
 42	int ret;
 43
 44	if (scheduler->init_service) {
 45		ret = scheduler->init_service(svc);
 46		if (ret) {
 47			pr_err("%s(): init error\n", __func__);
 48			return ret;
 49		}
 50	}
 51	rcu_assign_pointer(svc->scheduler, scheduler);
 52	return 0;
 53}
 54
 55
 56/*
 57 *  Unbind a service with its scheduler
 58 */
 59void ip_vs_unbind_scheduler(struct ip_vs_service *svc,
 60			    struct ip_vs_scheduler *sched)
 61{
 62	struct ip_vs_scheduler *cur_sched;
 63
 64	cur_sched = rcu_dereference_protected(svc->scheduler, 1);
 65	/* This check proves that old 'sched' was installed */
 66	if (!cur_sched)
 67		return;
 68
 69	if (sched->done_service)
 70		sched->done_service(svc);
 71	/* svc->scheduler can be set to NULL only by caller */
 72}
 73
 74
 75/*
 76 *  Get scheduler in the scheduler list by name
 77 */
 78static struct ip_vs_scheduler *ip_vs_sched_getbyname(const char *sched_name)
 79{
 80	struct ip_vs_scheduler *sched;
 81
 82	IP_VS_DBG(2, "%s(): sched_name \"%s\"\n", __func__, sched_name);
 83
 84	mutex_lock(&ip_vs_sched_mutex);
 85
 86	list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
 87		/*
 88		 * Test and get the modules atomically
 89		 */
 90		if (sched->module && !try_module_get(sched->module)) {
 91			/*
 92			 * This scheduler is just deleted
 93			 */
 94			continue;
 95		}
 96		if (strcmp(sched_name, sched->name)==0) {
 97			/* HIT */
 98			mutex_unlock(&ip_vs_sched_mutex);
 99			return sched;
100		}
101		module_put(sched->module);
102	}
103
104	mutex_unlock(&ip_vs_sched_mutex);
105	return NULL;
106}
107
108
109/*
110 *  Lookup scheduler and try to load it if it doesn't exist
111 */
112struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name)
113{
114	struct ip_vs_scheduler *sched;
115
116	/*
117	 *  Search for the scheduler by sched_name
118	 */
119	sched = ip_vs_sched_getbyname(sched_name);
120
121	/*
122	 *  If scheduler not found, load the module and search again
123	 */
124	if (sched == NULL) {
125		request_module("ip_vs_%s", sched_name);
126		sched = ip_vs_sched_getbyname(sched_name);
127	}
128
129	return sched;
130}
131
132void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler)
133{
134	if (scheduler)
135		module_put(scheduler->module);
136}
137
138/*
139 * Common error output helper for schedulers
140 */
141
142void ip_vs_scheduler_err(struct ip_vs_service *svc, const char *msg)
143{
144	struct ip_vs_scheduler *sched = rcu_dereference(svc->scheduler);
145	char *sched_name = sched ? sched->name : "none";
146
147	if (svc->fwmark) {
148		IP_VS_ERR_RL("%s: FWM %u 0x%08X - %s\n",
149			     sched_name, svc->fwmark, svc->fwmark, msg);
150#ifdef CONFIG_IP_VS_IPV6
151	} else if (svc->af == AF_INET6) {
152		IP_VS_ERR_RL("%s: %s [%pI6c]:%d - %s\n",
153			     sched_name, ip_vs_proto_name(svc->protocol),
154			     &svc->addr.in6, ntohs(svc->port), msg);
155#endif
156	} else {
157		IP_VS_ERR_RL("%s: %s %pI4:%d - %s\n",
158			     sched_name, ip_vs_proto_name(svc->protocol),
159			     &svc->addr.ip, ntohs(svc->port), msg);
160	}
161}
162
163/*
164 *  Register a scheduler in the scheduler list
165 */
166int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
167{
168	struct ip_vs_scheduler *sched;
169
170	if (!scheduler) {
171		pr_err("%s(): NULL arg\n", __func__);
172		return -EINVAL;
173	}
174
175	if (!scheduler->name) {
176		pr_err("%s(): NULL scheduler_name\n", __func__);
177		return -EINVAL;
178	}
179
180	/* increase the module use count */
181	if (!ip_vs_use_count_inc())
182		return -ENOENT;
183
184	mutex_lock(&ip_vs_sched_mutex);
185
186	if (!list_empty(&scheduler->n_list)) {
187		mutex_unlock(&ip_vs_sched_mutex);
188		ip_vs_use_count_dec();
189		pr_err("%s(): [%s] scheduler already linked\n",
190		       __func__, scheduler->name);
191		return -EINVAL;
192	}
193
194	/*
195	 *  Make sure that the scheduler with this name doesn't exist
196	 *  in the scheduler list.
197	 */
198	list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
199		if (strcmp(scheduler->name, sched->name) == 0) {
200			mutex_unlock(&ip_vs_sched_mutex);
201			ip_vs_use_count_dec();
202			pr_err("%s(): [%s] scheduler already existed "
203			       "in the system\n", __func__, scheduler->name);
204			return -EINVAL;
205		}
206	}
207	/*
208	 *	Add it into the d-linked scheduler list
209	 */
210	list_add(&scheduler->n_list, &ip_vs_schedulers);
211	mutex_unlock(&ip_vs_sched_mutex);
212
213	pr_info("[%s] scheduler registered.\n", scheduler->name);
214
215	return 0;
216}
217
218
219/*
220 *  Unregister a scheduler from the scheduler list
221 */
222int unregister_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
223{
224	if (!scheduler) {
225		pr_err("%s(): NULL arg\n", __func__);
226		return -EINVAL;
227	}
228
229	mutex_lock(&ip_vs_sched_mutex);
230	if (list_empty(&scheduler->n_list)) {
231		mutex_unlock(&ip_vs_sched_mutex);
232		pr_err("%s(): [%s] scheduler is not in the list. failed\n",
233		       __func__, scheduler->name);
234		return -EINVAL;
235	}
236
237	/*
238	 *	Remove it from the d-linked scheduler list
239	 */
240	list_del(&scheduler->n_list);
241	mutex_unlock(&ip_vs_sched_mutex);
242
243	/* decrease the module use count */
244	ip_vs_use_count_dec();
245
246	pr_info("[%s] scheduler unregistered.\n", scheduler->name);
247
248	return 0;
249}