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 #include <linux/module.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/interrupt.h>
  23 #include <asm/string.h>
  24 #include <linux/kmod.h>
  25 #include <linux/sysctl.h>
  26
  27 #include <net/ip_vs.h>
  28
  29 /*
  30  *  IPVS scheduler list
  31  */
  32 static LIST_HEAD(ip_vs_schedulers);
  33
  34 /* lock for service table */
  35 static DEFINE_RWLOCK(__ip_vs_sched_lock);
  36
  37
  38 /*
  39  *  Bind a service with a scheduler
  40  */
  41 int ip_vs_bind_scheduler(struct ip_vs_service *svc,
  42                          struct ip_vs_scheduler *scheduler)
  43 {
  44         int ret;
  45
  46         if (svc == NULL) {
  47                 IP_VS_ERR("ip_vs_bind_scheduler(): svc arg NULL\n");
  48                 return -EINVAL;
  49         }
  50         if (scheduler == NULL) {
  51                 IP_VS_ERR("ip_vs_bind_scheduler(): scheduler arg NULL\n");
  52                 return -EINVAL;
  53         }
  54
  55         svc->scheduler = scheduler;
  56
  57         if (scheduler->init_service) {
  58                 ret = scheduler->init_service(svc);
  59                 if (ret) {
  60                         IP_VS_ERR("ip_vs_bind_scheduler(): init error\n");
  61                         return ret;
  62                 }
  63         }
  64
  65         return 0;
  66 }
  67
  68
  69 /*
  70  *  Unbind a service with its scheduler
  71  */
  72 int ip_vs_unbind_scheduler(struct ip_vs_service *svc)
  73 {
  74         struct ip_vs_scheduler *sched;
  75
  76         if (svc == NULL) {
  77                 IP_VS_ERR("ip_vs_unbind_scheduler(): svc arg NULL\n");
  78                 return -EINVAL;
  79         }
  80
  81         sched = svc->scheduler;
  82         if (sched == NULL) {
  83                 IP_VS_ERR("ip_vs_unbind_scheduler(): svc isn't bound\n");
  84                 return -EINVAL;
  85         }
  86
  87         if (sched->done_service) {
  88                 if (sched->done_service(svc) != 0) {
  89                         IP_VS_ERR("ip_vs_unbind_scheduler(): done error\n");
  90                         return -EINVAL;
  91                 }
  92         }
  93
  94         svc->scheduler = NULL;
  95         return 0;
  96 }
  97
  98
  99 /*
 100  *  Get scheduler in the scheduler list by name
 101  */
 102 static struct ip_vs_scheduler *ip_vs_sched_getbyname(const char *sched_name)
 103 {
 104         struct ip_vs_scheduler *sched;
 105
 106         IP_VS_DBG(2, "ip_vs_sched_getbyname(): sched_name \"%s\"\n",
 107                   sched_name);
 108
 109         read_lock_bh(&__ip_vs_sched_lock);
 110
 111         list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
 112                 /*
 113                  * Test and get the modules atomically
 114                  */
 115                 if (sched->module && !try_module_get(sched->module)) {
 116                         /*
 117                          * This scheduler is just deleted
 118                          */
 119                         continue;
 120                 }
 121                 if (strcmp(sched_name, sched->name)==0) {
 122                         /* HIT */
 123                         read_unlock_bh(&__ip_vs_sched_lock);
 124                         return sched;
 125                 }
 126                 if (sched->module)
 127                         module_put(sched->module);
 128         }
 129
 130         read_unlock_bh(&__ip_vs_sched_lock);
 131         return NULL;
 132 }
 133
 134
 135 /*
 136  *  Lookup scheduler and try to load it if it doesn't exist
 137  */
 138 struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name)
 139 {
 140         struct ip_vs_scheduler *sched;
 141
 142         /*
 143          *  Search for the scheduler by sched_name
 144          */
 145         sched = ip_vs_sched_getbyname(sched_name);
 146
 147         /*
 148          *  If scheduler not found, load the module and search again
 149          */
 150         if (sched == NULL) {
 151                 request_module("ip_vs_%s", sched_name);
 152                 sched = ip_vs_sched_getbyname(sched_name);
 153         }
 154
 155         return sched;
 156 }
 157
 158 void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler)
 159 {
 160         if (scheduler->module)
 161                 module_put(scheduler->module);
 162 }
 163
 164
 165 /*
 166  *  Register a scheduler in the scheduler list
 167  */
 168 int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
 169 {
 170         struct ip_vs_scheduler *sched;
 171
 172         if (!scheduler) {
 173                 IP_VS_ERR("register_ip_vs_scheduler(): NULL arg\n");
 174                 return -EINVAL;
 175         }
 176
 177         if (!scheduler->name) {
 178                 IP_VS_ERR("register_ip_vs_scheduler(): NULL scheduler_name\n");
 179                 return -EINVAL;
 180         }
 181
 182         /* increase the module use count */
 183         ip_vs_use_count_inc();
 184
 185         write_lock_bh(&__ip_vs_sched_lock);
 186
 187         if (!list_empty(&scheduler->n_list)) {
 188                 write_unlock_bh(&__ip_vs_sched_lock);
 189                 ip_vs_use_count_dec();
 190                 IP_VS_ERR("register_ip_vs_scheduler(): [%s] scheduler "
 191                           "already linked\n", 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                         write_unlock_bh(&__ip_vs_sched_lock);
 202                         ip_vs_use_count_dec();
 203                         IP_VS_ERR("register_ip_vs_scheduler(): [%s] scheduler "
 204                                         "already existed in the system\n",
 205                                         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 (list_empty(&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 }