net/ipv4/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  * 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/sched.h>
  24 #include <linux/spinlock.h>
  25 #include <linux/interrupt.h>
  26 #include <asm/string.h>
  27 #include <linux/kmod.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         /*
 188          *  Make sure that the scheduler with this name doesn't exist
 189          *  in the scheduler list.
 190          */
 191         sched = ip_vs_sched_getbyname(scheduler->name);
 192         if (sched) {
 193                 ip_vs_scheduler_put(sched);
 194                 ip_vs_use_count_dec();
 195                 IP_VS_ERR("register_ip_vs_scheduler(): [%s] scheduler "
 196                           "already existed in the system\n", scheduler->name);
 197                 return -EINVAL;
 198         }
 199
 200         write_lock_bh(&__ip_vs_sched_lock);
 201
 202         if (scheduler->n_list.next != &scheduler->n_list) {
 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 linked\n", scheduler->name);
 207                 return -EINVAL;
 208         }
 209
 210         /*
 211          *      Add it into the d-linked scheduler list
 212          */
 213         list_add(&scheduler->n_list, &ip_vs_schedulers);
 214         write_unlock_bh(&__ip_vs_sched_lock);
 215
 216         IP_VS_INFO("[%s] scheduler registered.\n", scheduler->name);
 217
 218         return 0;
 219 }
 220
 221
 222 /*
 223  *  Unregister a scheduler from the scheduler list
 224  */
 225 int unregister_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
 226 {
 227         if (!scheduler) {
 228                 IP_VS_ERR( "unregister_ip_vs_scheduler(): NULL arg\n");
 229                 return -EINVAL;
 230         }
 231
 232         write_lock_bh(&__ip_vs_sched_lock);
 233         if (scheduler->n_list.next == &scheduler->n_list) {
 234                 write_unlock_bh(&__ip_vs_sched_lock);
 235                 IP_VS_ERR("unregister_ip_vs_scheduler(): [%s] scheduler "
 236                           "is not in the list. failed\n", scheduler->name);
 237                 return -EINVAL;
 238         }
 239
 240         /*
 241          *      Remove it from the d-linked scheduler list
 242          */
 243         list_del(&scheduler->n_list);
 244         write_unlock_bh(&__ip_vs_sched_lock);
 245
 246         /* decrease the module use count */
 247         ip_vs_use_count_dec();
 248
 249         IP_VS_INFO("[%s] scheduler unregistered.\n", scheduler->name);
 250
 251         return 0;
 252 }