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 EXPORT_SYMBOL(ip_vs_scheduler_err);
  33 /*
  34  *  IPVS scheduler list
  35  */
  36 static LIST_HEAD(ip_vs_schedulers);
  37
  38 /* semaphore for schedulers */
  39 static DEFINE_MUTEX(ip_vs_sched_mutex);
  40
  41
  42 /*
  43  *  Bind a service with a scheduler
  44  */
  45 int ip_vs_bind_scheduler(struct ip_vs_service *svc,
  46                          struct ip_vs_scheduler *scheduler)
  47 {
  48         int ret;
  49
  50         if (scheduler->init_service) {
  51                 ret = scheduler->init_service(svc);
  52                 if (ret) {
  53                         pr_err("%s(): init error\n", __func__);
  54                         return ret;
  55                 }
  56         }
  57         rcu_assign_pointer(svc->scheduler, scheduler);
  58         return 0;
  59 }
  60
  61
  62 /*
  63  *  Unbind a service with its scheduler
  64  */
  65 void ip_vs_unbind_scheduler(struct ip_vs_service *svc,
  66                             struct ip_vs_scheduler *sched)
  67 {
  68         struct ip_vs_scheduler *cur_sched;
  69
  70         cur_sched = rcu_dereference_protected(svc->scheduler, 1);
  71         /* This check proves that old 'sched' was installed */
  72         if (!cur_sched)
  73                 return;
  74
  75         if (sched->done_service)
  76                 sched->done_service(svc);
  77         /* svc->scheduler can be set to NULL only by caller */
  78 }
  79
  80
  81 /*
  82  *  Get scheduler in the scheduler list by name
  83  */
  84 static struct ip_vs_scheduler *ip_vs_sched_getbyname(const char *sched_name)
  85 {
  86         struct ip_vs_scheduler *sched;
  87
  88         IP_VS_DBG(2, "%s(): sched_name \"%s\"\n", __func__, sched_name);
  89
  90         mutex_lock(&ip_vs_sched_mutex);
  91
  92         list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
  93                 /*
  94                  * Test and get the modules atomically
  95                  */
  96                 if (sched->module && !try_module_get(sched->module)) {
  97                         /*
  98                          * This scheduler is just deleted
  99                          */
 100                         continue;
 101                 }
 102                 if (strcmp(sched_name, sched->name)==0) {
 103                         /* HIT */
 104                         mutex_unlock(&ip_vs_sched_mutex);
 105                         return sched;
 106                 }
 107                 module_put(sched->module);
 108         }
 109
 110         mutex_unlock(&ip_vs_sched_mutex);
 111         return NULL;
 112 }
 113
 114
 115 /*
 116  *  Lookup scheduler and try to load it if it doesn't exist
 117  */
 118 struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name)
 119 {
 120         struct ip_vs_scheduler *sched;
 121
 122         /*
 123          *  Search for the scheduler by sched_name
 124          */
 125         sched = ip_vs_sched_getbyname(sched_name);
 126
 127         /*
 128          *  If scheduler not found, load the module and search again
 129          */
 130         if (sched == NULL) {
 131                 request_module("ip_vs_%s", sched_name);
 132                 sched = ip_vs_sched_getbyname(sched_name);
 133         }
 134
 135         return sched;
 136 }
 137
 138 void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler)
 139 {
 140         if (scheduler)
 141                 module_put(scheduler->module);
 142 }
 143
 144 /*
 145  * Common error output helper for schedulers
 146  */
 147
 148 void ip_vs_scheduler_err(struct ip_vs_service *svc, const char *msg)
 149 {
 150         struct ip_vs_scheduler *sched = rcu_dereference(svc->scheduler);
 151         char *sched_name = sched ? sched->name : "none";
 152
 153         if (svc->fwmark) {
 154                 IP_VS_ERR_RL("%s: FWM %u 0x%08X - %s\n",
 155                              sched_name, svc->fwmark, svc->fwmark, msg);
 156 #ifdef CONFIG_IP_VS_IPV6
 157         } else if (svc->af == AF_INET6) {
 158                 IP_VS_ERR_RL("%s: %s [%pI6c]:%d - %s\n",
 159                              sched_name, ip_vs_proto_name(svc->protocol),
 160                              &svc->addr.in6, ntohs(svc->port), msg);
 161 #endif
 162         } else {
 163                 IP_VS_ERR_RL("%s: %s %pI4:%d - %s\n",
 164                              sched_name, ip_vs_proto_name(svc->protocol),
 165                              &svc->addr.ip, ntohs(svc->port), msg);
 166         }
 167 }
 168
 169 /*
 170  *  Register a scheduler in the scheduler list
 171  */
 172 int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
 173 {
 174         struct ip_vs_scheduler *sched;
 175
 176         if (!scheduler) {
 177                 pr_err("%s(): NULL arg\n", __func__);
 178                 return -EINVAL;
 179         }
 180
 181         if (!scheduler->name) {
 182                 pr_err("%s(): NULL scheduler_name\n", __func__);
 183                 return -EINVAL;
 184         }
 185
 186         /* increase the module use count */
 187         ip_vs_use_count_inc();
 188
 189         mutex_lock(&ip_vs_sched_mutex);
 190
 191         if (!list_empty(&scheduler->n_list)) {
 192                 mutex_unlock(&ip_vs_sched_mutex);
 193                 ip_vs_use_count_dec();
 194                 pr_err("%s(): [%s] scheduler already linked\n",
 195                        __func__, scheduler->name);
 196                 return -EINVAL;
 197         }
 198
 199         /*
 200          *  Make sure that the scheduler with this name doesn't exist
 201          *  in the scheduler list.
 202          */
 203         list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
 204                 if (strcmp(scheduler->name, sched->name) == 0) {
 205                         mutex_unlock(&ip_vs_sched_mutex);
 206                         ip_vs_use_count_dec();
 207                         pr_err("%s(): [%s] scheduler already existed "
 208                                "in the system\n", __func__, scheduler->name);
 209                         return -EINVAL;
 210                 }
 211         }
 212         /*
 213          *      Add it into the d-linked scheduler list
 214          */
 215         list_add(&scheduler->n_list, &ip_vs_schedulers);
 216         mutex_unlock(&ip_vs_sched_mutex);
 217
 218         pr_info("[%s] scheduler registered.\n", scheduler->name);
 219
 220         return 0;
 221 }
 222
 223
 224 /*
 225  *  Unregister a scheduler from the scheduler list
 226  */
 227 int unregister_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
 228 {
 229         if (!scheduler) {
 230                 pr_err("%s(): NULL arg\n", __func__);
 231                 return -EINVAL;
 232         }
 233
 234         mutex_lock(&ip_vs_sched_mutex);
 235         if (list_empty(&scheduler->n_list)) {
 236                 mutex_unlock(&ip_vs_sched_mutex);
 237                 pr_err("%s(): [%s] scheduler is not in the list. failed\n",
 238                        __func__, scheduler->name);
 239                 return -EINVAL;
 240         }
 241
 242         /*
 243          *      Remove it from the d-linked scheduler list
 244          */
 245         list_del(&scheduler->n_list);
 246         mutex_unlock(&ip_vs_sched_mutex);
 247
 248         /* decrease the module use count */
 249         ip_vs_use_count_dec();
 250
 251         pr_info("[%s] scheduler unregistered.\n", scheduler->name);
 252
 253         return 0;
 254 }