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_SPINLOCK(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         svc->scheduler = scheduler;
  50
  51         if (scheduler->init_service) {
  52                 ret = scheduler->init_service(svc);
  53                 if (ret) {
  54                         pr_err("%s(): init error\n", __func__);
  55                         return ret;
  56                 }
  57         }
  58
  59         return 0;
  60 }
  61
  62
  63 /*
  64  *  Unbind a service with its scheduler
  65  */
  66 int ip_vs_unbind_scheduler(struct ip_vs_service *svc)
  67 {
  68         struct ip_vs_scheduler *sched = svc->scheduler;
  69
  70         if (!sched)
  71                 return 0;
  72
  73         if (sched->done_service) {
  74                 if (sched->done_service(svc) != 0) {
  75                         pr_err("%s(): done error\n", __func__);
  76                         return -EINVAL;
  77                 }
  78         }
  79
  80         svc->scheduler = NULL;
  81         return 0;
  82 }
  83
  84
  85 /*
  86  *  Get scheduler in the scheduler list by name
  87  */
  88 static struct ip_vs_scheduler *ip_vs_sched_getbyname(const char *sched_name)
  89 {
  90         struct ip_vs_scheduler *sched;
  91
  92         IP_VS_DBG(2, "%s(): sched_name \"%s\"\n", __func__, sched_name);
  93
  94         spin_lock_bh(&ip_vs_sched_lock);
  95
  96         list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
  97                 /*
  98                  * Test and get the modules atomically
  99                  */
 100                 if (sched->module && !try_module_get(sched->module)) {
 101                         /*
 102                          * This scheduler is just deleted
 103                          */
 104                         continue;
 105                 }
 106                 if (strcmp(sched_name, sched->name)==0) {
 107                         /* HIT */
 108                         spin_unlock_bh(&ip_vs_sched_lock);
 109                         return sched;
 110                 }
 111                 if (sched->module)
 112                         module_put(sched->module);
 113         }
 114
 115         spin_unlock_bh(&ip_vs_sched_lock);
 116         return NULL;
 117 }
 118
 119
 120 /*
 121  *  Lookup scheduler and try to load it if it doesn't exist
 122  */
 123 struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name)
 124 {
 125         struct ip_vs_scheduler *sched;
 126
 127         /*
 128          *  Search for the scheduler by sched_name
 129          */
 130         sched = ip_vs_sched_getbyname(sched_name);
 131
 132         /*
 133          *  If scheduler not found, load the module and search again
 134          */
 135         if (sched == NULL) {
 136                 request_module("ip_vs_%s", sched_name);
 137                 sched = ip_vs_sched_getbyname(sched_name);
 138         }
 139
 140         return sched;
 141 }
 142
 143 void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler)
 144 {
 145         if (scheduler && scheduler->module)
 146                 module_put(scheduler->module);
 147 }
 148
 149
 150 /*
 151  *  Register a scheduler in the scheduler list
 152  */
 153 int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
 154 {
 155         struct ip_vs_scheduler *sched;
 156
 157         if (!scheduler) {
 158                 pr_err("%s(): NULL arg\n", __func__);
 159                 return -EINVAL;
 160         }
 161
 162         if (!scheduler->name) {
 163                 pr_err("%s(): NULL scheduler_name\n", __func__);
 164                 return -EINVAL;
 165         }
 166
 167         /* increase the module use count */
 168         ip_vs_use_count_inc();
 169
 170         spin_lock_bh(&ip_vs_sched_lock);
 171
 172         if (!list_empty(&scheduler->n_list)) {
 173                 spin_unlock_bh(&ip_vs_sched_lock);
 174                 ip_vs_use_count_dec();
 175                 pr_err("%s(): [%s] scheduler already linked\n",
 176                        __func__, scheduler->name);
 177                 return -EINVAL;
 178         }
 179
 180         /*
 181          *  Make sure that the scheduler with this name doesn't exist
 182          *  in the scheduler list.
 183          */
 184         list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
 185                 if (strcmp(scheduler->name, sched->name) == 0) {
 186                         spin_unlock_bh(&ip_vs_sched_lock);
 187                         ip_vs_use_count_dec();
 188                         pr_err("%s(): [%s] scheduler already existed "
 189                                "in the system\n", __func__, scheduler->name);
 190                         return -EINVAL;
 191                 }
 192         }
 193         /*
 194          *      Add it into the d-linked scheduler list
 195          */
 196         list_add(&scheduler->n_list, &ip_vs_schedulers);
 197         spin_unlock_bh(&ip_vs_sched_lock);
 198
 199         pr_info("[%s] scheduler registered.\n", scheduler->name);
 200
 201         return 0;
 202 }
 203
 204
 205 /*
 206  *  Unregister a scheduler from the scheduler list
 207  */
 208 int unregister_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
 209 {
 210         if (!scheduler) {
 211                 pr_err("%s(): NULL arg\n", __func__);
 212                 return -EINVAL;
 213         }
 214
 215         spin_lock_bh(&ip_vs_sched_lock);
 216         if (list_empty(&scheduler->n_list)) {
 217                 spin_unlock_bh(&ip_vs_sched_lock);
 218                 pr_err("%s(): [%s] scheduler is not in the list. failed\n",
 219                        __func__, scheduler->name);
 220                 return -EINVAL;
 221         }
 222
 223         /*
 224          *      Remove it from the d-linked scheduler list
 225          */
 226         list_del(&scheduler->n_list);
 227         spin_unlock_bh(&ip_vs_sched_lock);
 228
 229         /* decrease the module use count */
 230         ip_vs_use_count_dec();
 231
 232         pr_info("[%s] scheduler unregistered.\n", scheduler->name);
 233
 234         return 0;
 235 }