linux/net/netfilter/ipvs/ip_vs_sched.c
<<
>>
Prefs
   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 */
  32static LIST_HEAD(ip_vs_schedulers);
  33
  34/* lock for service table */
  35static DEFINE_RWLOCK(__ip_vs_sched_lock);
  36
  37
  38/*
  39 *  Bind a service with a scheduler
  40 */
  41int 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 */
  72int 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 */
 102static 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 */
 138struct 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
 158void 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 */
 168int 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 */
 224int 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}
 252