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 <asm/string.h>
  26 #include <linux/kmod.h>
  27
  28 #include <net/ip_vs.h>
  29
  30 /*
  31  *  IPVS scheduler list
  32  */
  33 static LIST_HEAD(ip_vs_schedulers);
  34
  35 /* lock for service table */
  36 static DEFINE_RWLOCK(__ip_vs_sched_lock);
  37
  38
  39 /*
  40  *  Bind a service with a scheduler
  41  */
  42 int ip_vs_bind_scheduler(struct ip_vs_service *svc,
  43                          struct ip_vs_scheduler *scheduler)
  44 {
  45         int ret;
  46
  47         if (svc == NULL) {
  48                 IP_VS_ERR("ip_vs_bind_scheduler(): svc arg NULL\n");
  49                 return -EINVAL;
  50         }
  51         if (scheduler == NULL) {
  52                 IP_VS_ERR("ip_vs_bind_scheduler(): scheduler arg NULL\n");
  53                 return -EINVAL;
  54         }
  55
  56         svc->scheduler = scheduler;
  57
  58         if (scheduler->init_service) {
  59                 ret = scheduler->init_service(svc);
  60                 if (ret) {
  61                         IP_VS_ERR("ip_vs_bind_scheduler(): init error\n");
  62                         return ret;
  63                 }
  64         }
  65
  66         return 0;
  67 }
  68
  69
  70 /*
  71  *  Unbind a service with its scheduler
  72  */
  73 int ip_vs_unbind_scheduler(struct ip_vs_service *svc)
  74 {
  75         struct ip_vs_scheduler *sched;
  76
  77         if (svc == NULL) {
  78                 IP_VS_ERR("ip_vs_unbind_scheduler(): svc arg NULL\n");
  79                 return -EINVAL;
  80         }
  81
  82         sched = svc->scheduler;
  83         if (sched == NULL) {
  84                 IP_VS_ERR("ip_vs_unbind_scheduler(): svc isn't bound\n");
  85                 return -EINVAL;
  86         }
  87
  88         if (sched->done_service) {
  89                 if (sched->done_service(svc) != 0) {
  90                         IP_VS_ERR("ip_vs_unbind_scheduler(): done error\n");
  91                         return -EINVAL;
  92                 }
  93         }
  94
  95         svc->scheduler = NULL;
  96         return 0;
  97 }
  98
  99
 100 /*
 101  *  Get scheduler in the scheduler list by name
 102  */
 103 static struct ip_vs_scheduler *ip_vs_sched_getbyname(const char *sched_name)
 104 {
 105         struct ip_vs_scheduler *sched;
 106
 107         IP_VS_DBG(2, "ip_vs_sched_getbyname(): sched_name \"%s\"\n",
 108                   sched_name);
 109
 110         read_lock_bh(&__ip_vs_sched_lock);
 111
 112         list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
 113                 /*
 114                  * Test and get the modules atomically
 115                  */
 116                 if (sched->module && !try_module_get(sched->module)) {
 117                         /*
 118                          * This scheduler is just deleted
 119                          */
 120                         continue;
 121                 }
 122                 if (strcmp(sched_name, sched->name)==0) {
 123                         /* HIT */
 124                         read_unlock_bh(&__ip_vs_sched_lock);
 125                         return sched;
 126                 }
 127                 if (sched->module)
 128                         module_put(sched->module);
 129         }
 130
 131         read_unlock_bh(&__ip_vs_sched_lock);
 132         return NULL;
 133 }
 134
 135
 136 /*
 137  *  Lookup scheduler and try to load it if it doesn't exist
 138  */
 139 struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name)
 140 {
 141         struct ip_vs_scheduler *sched;
 142
 143         /*
 144          *  Search for the scheduler by sched_name
 145          */
 146         sched = ip_vs_sched_getbyname(sched_name);
 147
 148         /*
 149          *  If scheduler not found, load the module and search again
 150          */
 151         if (sched == NULL) {
 152                 request_module("ip_vs_%s", sched_name);
 153                 sched = ip_vs_sched_getbyname(sched_name);
 154         }
 155
 156         return sched;
 157 }
 158
 159 void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler)
 160 {
 161         if (scheduler->module)
 162                 module_put(scheduler->module);
 163 }
 164
 165
 166 /*
 167  *  Register a scheduler in the scheduler list
 168  */
 169 int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
 170 {
 171         struct ip_vs_scheduler *sched;
 172
 173         if (!scheduler) {
 174                 IP_VS_ERR("register_ip_vs_scheduler(): NULL arg\n");
 175                 return -EINVAL;
 176         }
 177
 178         if (!scheduler->name) {
 179                 IP_VS_ERR("register_ip_vs_scheduler(): NULL scheduler_name\n");
 180                 return -EINVAL;
 181         }
 182
 183         /* increase the module use count */
 184         ip_vs_use_count_inc();
 185
 186         /*
 187          *  Make sure that the scheduler with this name doesn't exist
 188          *  in the scheduler list.
 189          */
 190         sched = ip_vs_sched_getbyname(scheduler->name);
 191         if (sched) {
 192                 ip_vs_scheduler_put(sched);
 193                 ip_vs_use_count_dec();
 194                 IP_VS_ERR("register_ip_vs_scheduler(): [%s] scheduler "
 195                           "already existed in the system\n", scheduler->name);
 196                 return -EINVAL;
 197         }
 198
 199         write_lock_bh(&__ip_vs_sched_lock);
 200
 201         if (scheduler->n_list.next != &scheduler->n_list) {
 202                 write_unlock_bh(&__ip_vs_sched_lock);
 203                 ip_vs_use_count_dec();
 204                 IP_VS_ERR("register_ip_vs_scheduler(): [%s] scheduler "
 205                           "already linked\n", 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 (scheduler->n_list.next == &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 }