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 /*
  33  *  IPVS scheduler list
  34  */
  35 static LIST_HEAD(ip_vs_schedulers);
  36
  37 /* lock for service table */
  38 static DEFINE_RWLOCK(__ip_vs_sched_lock);
  39
  40
  41 /*
  42  *  Bind a service with a scheduler
  43  */
  44 int ip_vs_bind_scheduler(struct ip_vs_service *svc,
  45                          struct ip_vs_scheduler *scheduler)
  46 {
  47         int ret;
  48
  49         if (svc == NULL) {
  50                 pr_err("%s(): svc arg NULL\n", __func__);
  51                 return -EINVAL;
  52         }
  53         if (scheduler == NULL) {
  54                 pr_err("%s(): scheduler arg NULL\n", __func__);
  55                 return -EINVAL;
  56         }
  57
  58         svc->scheduler = scheduler;
  59
  60         if (scheduler->init_service) {
  61                 ret = scheduler->init_service(svc);
  62                 if (ret) {
  63                         pr_err("%s(): init error\n", __func__);
  64                         return ret;
  65                 }
  66         }
  67
  68         return 0;
  69 }
  70
  71
  72 /*
  73  *  Unbind a service with its scheduler
  74  */
  75 int ip_vs_unbind_scheduler(struct ip_vs_service *svc)
  76 {
  77         struct ip_vs_scheduler *sched;
  78
  79         if (svc == NULL) {
  80                 pr_err("%s(): svc arg NULL\n", __func__);
  81                 return -EINVAL;
  82         }
  83
  84         sched = svc->scheduler;
  85         if (sched == NULL) {
  86                 pr_err("%s(): svc isn't bound\n", __func__);
  87                 return -EINVAL;
  88         }
  89
  90         if (sched->done_service) {
  91                 if (sched->done_service(svc) != 0) {
  92                         pr_err("%s(): done error\n", __func__);
  93                         return -EINVAL;
  94                 }
  95         }
  96
  97         svc->scheduler = NULL;
  98         return 0;
  99 }
 100
 101
 102 /*
 103  *  Get scheduler in the scheduler list by name
 104  */
 105 static struct ip_vs_scheduler *ip_vs_sched_getbyname(const char *sched_name)
 106 {
 107         struct ip_vs_scheduler *sched;
 108
 109         IP_VS_DBG(2, "%s(): sched_name \"%s\"\n", __func__, 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                 pr_err("%s(): NULL arg\n", __func__);
 176                 return -EINVAL;
 177         }
 178
 179         if (!scheduler->name) {
 180                 pr_err("%s(): NULL scheduler_name\n", __func__);
 181                 return -EINVAL;
 182         }
 183
 184         /* increase the module use count */
 185         ip_vs_use_count_inc();
 186
 187         write_lock_bh(&__ip_vs_sched_lock);
 188
 189         if (!list_empty(&scheduler->n_list)) {
 190                 write_unlock_bh(&__ip_vs_sched_lock);
 191                 ip_vs_use_count_dec();
 192                 pr_err("%s(): [%s] scheduler already linked\n",
 193                        __func__, scheduler->name);
 194                 return -EINVAL;
 195         }
 196
 197         /*
 198          *  Make sure that the scheduler with this name doesn't exist
 199          *  in the scheduler list.
 200          */
 201         list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
 202                 if (strcmp(scheduler->name, sched->name) == 0) {
 203                         write_unlock_bh(&__ip_vs_sched_lock);
 204                         ip_vs_use_count_dec();
 205                         pr_err("%s(): [%s] scheduler already existed "
 206                                "in the system\n", __func__, 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         pr_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                 pr_err("%s(): NULL arg\n", __func__);
 229                 return -EINVAL;
 230         }
 231
 232         write_lock_bh(&__ip_vs_sched_lock);
 233         if (list_empty(&scheduler->n_list)) {
 234                 write_unlock_bh(&__ip_vs_sched_lock);
 235                 pr_err("%s(): [%s] scheduler is not in the list. failed\n",
 236                        __func__, 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         pr_info("[%s] scheduler unregistered.\n", scheduler->name);
 250
 251         return 0;
 252 }