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 #define KMSG_COMPONENT "IPVS"
  21 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  22
  23 #include <linux/module.h>
  24 #include <linux/spinlock.h>
  25 #include <linux/interrupt.h>
  26 #include <asm/string.h>
  27 #include <linux/kmod.h>
  28 #include <linux/sysctl.h>
  29
  30 #include <net/ip_vs.h>
  31
  32 EXPORT_SYMBOL(ip_vs_scheduler_err);
  33 /*
  34  *  IPVS scheduler list
  35  */
  36 static LIST_HEAD(ip_vs_schedulers);
  37
  38 /* semaphore for schedulers */
  39 static DEFINE_MUTEX(ip_vs_sched_mutex);
  40
  41
  42 /*
  43  *  Bind a service with a scheduler
  44  */
  45 int ip_vs_bind_scheduler(struct ip_vs_service *svc,
  46                          struct ip_vs_scheduler *scheduler)
  47 {
  48         int ret;
  49
  50         svc->scheduler = scheduler;
  51
  52         if (scheduler->init_service) {
  53                 ret = scheduler->init_service(svc);
  54                 if (ret) {
  55                         pr_err("%s(): init error\n", __func__);
  56                         return ret;
  57                 }
  58         }
  59
  60         return 0;
  61 }
  62
  63
  64 /*
  65  *  Unbind a service with its scheduler
  66  */
  67 int ip_vs_unbind_scheduler(struct ip_vs_service *svc)
  68 {
  69         struct ip_vs_scheduler *sched = svc->scheduler;
  70
  71         if (!sched)
  72                 return 0;
  73
  74         if (sched->done_service) {
  75                 if (sched->done_service(svc) != 0) {
  76                         pr_err("%s(): done error\n", __func__);
  77                         return -EINVAL;
  78                 }
  79         }
  80
  81         svc->scheduler = NULL;
  82         return 0;
  83 }
  84
  85
  86 /*
  87  *  Get scheduler in the scheduler list by name
  88  */
  89 static struct ip_vs_scheduler *ip_vs_sched_getbyname(const char *sched_name)
  90 {
  91         struct ip_vs_scheduler *sched;
  92
  93         IP_VS_DBG(2, "%s(): sched_name \"%s\"\n", __func__, sched_name);
  94
  95         mutex_lock(&ip_vs_sched_mutex);
  96
  97         list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
  98                 /*
  99                  * Test and get the modules atomically
 100                  */
 101                 if (sched->module && !try_module_get(sched->module)) {
 102                         /*
 103                          * This scheduler is just deleted
 104                          */
 105                         continue;
 106                 }
 107                 if (strcmp(sched_name, sched->name)==0) {
 108                         /* HIT */
 109                         mutex_unlock(&ip_vs_sched_mutex);
 110                         return sched;
 111                 }
 112                 if (sched->module)
 113                         module_put(sched->module);
 114         }
 115
 116         mutex_unlock(&ip_vs_sched_mutex);
 117         return NULL;
 118 }
 119
 120
 121 /*
 122  *  Lookup scheduler and try to load it if it doesn't exist
 123  */
 124 struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name)
 125 {
 126         struct ip_vs_scheduler *sched;
 127
 128         /*
 129          *  Search for the scheduler by sched_name
 130          */
 131         sched = ip_vs_sched_getbyname(sched_name);
 132
 133         /*
 134          *  If scheduler not found, load the module and search again
 135          */
 136         if (sched == NULL) {
 137                 request_module("ip_vs_%s", sched_name);
 138                 sched = ip_vs_sched_getbyname(sched_name);
 139         }
 140
 141         return sched;
 142 }
 143
 144 void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler)
 145 {
 146         if (scheduler && scheduler->module)
 147                 module_put(scheduler->module);
 148 }
 149
 150 /*
 151  * Common error output helper for schedulers
 152  */
 153
 154 void ip_vs_scheduler_err(struct ip_vs_service *svc, const char *msg)
 155 {
 156         if (svc->fwmark) {
 157                 IP_VS_ERR_RL("%s: FWM %u 0x%08X - %s\n",
 158                              svc->scheduler->name, svc->fwmark,
 159                              svc->fwmark, msg);
 160 #ifdef CONFIG_IP_VS_IPV6
 161         } else if (svc->af == AF_INET6) {
 162                 IP_VS_ERR_RL("%s: %s [%pI6c]:%d - %s\n",
 163                              svc->scheduler->name,
 164                              ip_vs_proto_name(svc->protocol),
 165                              &svc->addr.in6, ntohs(svc->port), msg);
 166 #endif
 167         } else {
 168                 IP_VS_ERR_RL("%s: %s %pI4:%d - %s\n",
 169                              svc->scheduler->name,
 170                              ip_vs_proto_name(svc->protocol),
 171                              &svc->addr.ip, ntohs(svc->port), msg);
 172         }
 173 }
 174
 175 /*
 176  *  Register a scheduler in the scheduler list
 177  */
 178 int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
 179 {
 180         struct ip_vs_scheduler *sched;
 181
 182         if (!scheduler) {
 183                 pr_err("%s(): NULL arg\n", __func__);
 184                 return -EINVAL;
 185         }
 186
 187         if (!scheduler->name) {
 188                 pr_err("%s(): NULL scheduler_name\n", __func__);
 189                 return -EINVAL;
 190         }
 191
 192         /* increase the module use count */
 193         ip_vs_use_count_inc();
 194
 195         mutex_lock(&ip_vs_sched_mutex);
 196
 197         if (!list_empty(&scheduler->n_list)) {
 198                 mutex_unlock(&ip_vs_sched_mutex);
 199                 ip_vs_use_count_dec();
 200                 pr_err("%s(): [%s] scheduler already linked\n",
 201                        __func__, scheduler->name);
 202                 return -EINVAL;
 203         }
 204
 205         /*
 206          *  Make sure that the scheduler with this name doesn't exist
 207          *  in the scheduler list.
 208          */
 209         list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
 210                 if (strcmp(scheduler->name, sched->name) == 0) {
 211                         mutex_unlock(&ip_vs_sched_mutex);
 212                         ip_vs_use_count_dec();
 213                         pr_err("%s(): [%s] scheduler already existed "
 214                                "in the system\n", __func__, scheduler->name);
 215                         return -EINVAL;
 216                 }
 217         }
 218         /*
 219          *      Add it into the d-linked scheduler list
 220          */
 221         list_add(&scheduler->n_list, &ip_vs_schedulers);
 222         mutex_unlock(&ip_vs_sched_mutex);
 223
 224         pr_info("[%s] scheduler registered.\n", scheduler->name);
 225
 226         return 0;
 227 }
 228
 229
 230 /*
 231  *  Unregister a scheduler from the scheduler list
 232  */
 233 int unregister_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
 234 {
 235         if (!scheduler) {
 236                 pr_err("%s(): NULL arg\n", __func__);
 237                 return -EINVAL;
 238         }
 239
 240         mutex_lock(&ip_vs_sched_mutex);
 241         if (list_empty(&scheduler->n_list)) {
 242                 mutex_unlock(&ip_vs_sched_mutex);
 243                 pr_err("%s(): [%s] scheduler is not in the list. failed\n",
 244                        __func__, scheduler->name);
 245                 return -EINVAL;
 246         }
 247
 248         /*
 249          *      Remove it from the d-linked scheduler list
 250          */
 251         list_del(&scheduler->n_list);
 252         mutex_unlock(&ip_vs_sched_mutex);
 253
 254         /* decrease the module use count */
 255         ip_vs_use_count_dec();
 256
 257         pr_info("[%s] scheduler unregistered.\n", scheduler->name);
 258
 259         return 0;
 260 }