net/netfilter/ipvs/ip_vs_sched.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * IPVS         An implementation of the IP virtual server support for the
   4  *              LINUX operating system.  IPVS is now implemented as a module
   5  *              over the Netfilter framework. IPVS can be used to build a
   6  *              high-performance and highly available server based on a
   7  *              cluster of servers.
   8  *
   9  * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
  10  *              Peter Kese <peter.kese@ijs.si>
  11  *
  12  * Changes:
  13  */
  14
  15 #define KMSG_COMPONENT "IPVS"
  16 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  17
  18 #include <linux/module.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/interrupt.h>
  21 #include <asm/string.h>
  22 #include <linux/kmod.h>
  23 #include <linux/sysctl.h>
  24
  25 #include <net/ip_vs.h>
  26
  27 EXPORT_SYMBOL(ip_vs_scheduler_err);
  28 /*
  29  *  IPVS scheduler list
  30  */
  31 static LIST_HEAD(ip_vs_schedulers);
  32
  33 /* semaphore for schedulers */
  34 static DEFINE_MUTEX(ip_vs_sched_mutex);
  35
  36
  37 /*
  38  *  Bind a service with a scheduler
  39  */
  40 int ip_vs_bind_scheduler(struct ip_vs_service *svc,
  41                          struct ip_vs_scheduler *scheduler)
  42 {
  43         int ret;
  44
  45         if (scheduler->init_service) {
  46                 ret = scheduler->init_service(svc);
  47                 if (ret) {
  48                         pr_err("%s(): init error\n", __func__);
  49                         return ret;
  50                 }
  51         }
  52         rcu_assign_pointer(svc->scheduler, scheduler);
  53         return 0;
  54 }
  55
  56
  57 /*
  58  *  Unbind a service with its scheduler
  59  */
  60 void ip_vs_unbind_scheduler(struct ip_vs_service *svc,
  61                             struct ip_vs_scheduler *sched)
  62 {
  63         struct ip_vs_scheduler *cur_sched;
  64
  65         cur_sched = rcu_dereference_protected(svc->scheduler, 1);
  66         /* This check proves that old 'sched' was installed */
  67         if (!cur_sched)
  68                 return;
  69
  70         if (sched->done_service)
  71                 sched->done_service(svc);
  72         /* svc->scheduler can be set to NULL only by caller */
  73 }
  74
  75
  76 /*
  77  *  Get scheduler in the scheduler list by name
  78  */
  79 static struct ip_vs_scheduler *ip_vs_sched_getbyname(const char *sched_name)
  80 {
  81         struct ip_vs_scheduler *sched;
  82
  83         IP_VS_DBG(2, "%s(): sched_name \"%s\"\n", __func__, sched_name);
  84
  85         mutex_lock(&ip_vs_sched_mutex);
  86
  87         list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
  88                 /*
  89                  * Test and get the modules atomically
  90                  */
  91                 if (sched->module && !try_module_get(sched->module)) {
  92                         /*
  93                          * This scheduler is just deleted
  94                          */
  95                         continue;
  96                 }
  97                 if (strcmp(sched_name, sched->name)==0) {
  98                         /* HIT */
  99                         mutex_unlock(&ip_vs_sched_mutex);
 100                         return sched;
 101                 }
 102                 module_put(sched->module);
 103         }
 104
 105         mutex_unlock(&ip_vs_sched_mutex);
 106         return NULL;
 107 }
 108
 109
 110 /*
 111  *  Lookup scheduler and try to load it if it doesn't exist
 112  */
 113 struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name)
 114 {
 115         struct ip_vs_scheduler *sched;
 116
 117         /*
 118          *  Search for the scheduler by sched_name
 119          */
 120         sched = ip_vs_sched_getbyname(sched_name);
 121
 122         /*
 123          *  If scheduler not found, load the module and search again
 124          */
 125         if (sched == NULL) {
 126                 request_module("ip_vs_%s", sched_name);
 127                 sched = ip_vs_sched_getbyname(sched_name);
 128         }
 129
 130         return sched;
 131 }
 132
 133 void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler)
 134 {
 135         if (scheduler)
 136                 module_put(scheduler->module);
 137 }
 138
 139 /*
 140  * Common error output helper for schedulers
 141  */
 142
 143 void ip_vs_scheduler_err(struct ip_vs_service *svc, const char *msg)
 144 {
 145         struct ip_vs_scheduler *sched = rcu_dereference(svc->scheduler);
 146         char *sched_name = sched ? sched->name : "none";
 147
 148         if (svc->fwmark) {
 149                 IP_VS_ERR_RL("%s: FWM %u 0x%08X - %s\n",
 150                              sched_name, svc->fwmark, svc->fwmark, msg);
 151 #ifdef CONFIG_IP_VS_IPV6
 152         } else if (svc->af == AF_INET6) {
 153                 IP_VS_ERR_RL("%s: %s [%pI6c]:%d - %s\n",
 154                              sched_name, ip_vs_proto_name(svc->protocol),
 155                              &svc->addr.in6, ntohs(svc->port), msg);
 156 #endif
 157         } else {
 158                 IP_VS_ERR_RL("%s: %s %pI4:%d - %s\n",
 159                              sched_name, ip_vs_proto_name(svc->protocol),
 160                              &svc->addr.ip, ntohs(svc->port), msg);
 161         }
 162 }
 163
 164 /*
 165  *  Register a scheduler in the scheduler list
 166  */
 167 int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
 168 {
 169         struct ip_vs_scheduler *sched;
 170
 171         if (!scheduler) {
 172                 pr_err("%s(): NULL arg\n", __func__);
 173                 return -EINVAL;
 174         }
 175
 176         if (!scheduler->name) {
 177                 pr_err("%s(): NULL scheduler_name\n", __func__);
 178                 return -EINVAL;
 179         }
 180
 181         /* increase the module use count */
 182         if (!ip_vs_use_count_inc())
 183                 return -ENOENT;
 184
 185         mutex_lock(&ip_vs_sched_mutex);
 186
 187         if (!list_empty(&scheduler->n_list)) {
 188                 mutex_unlock(&ip_vs_sched_mutex);
 189                 ip_vs_use_count_dec();
 190                 pr_err("%s(): [%s] scheduler already linked\n",
 191                        __func__, 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                         mutex_unlock(&ip_vs_sched_mutex);
 202                         ip_vs_use_count_dec();
 203                         pr_err("%s(): [%s] scheduler already existed "
 204                                "in the system\n", __func__, scheduler->name);
 205                         return -EINVAL;
 206                 }
 207         }
 208         /*
 209          *      Add it into the d-linked scheduler list
 210          */
 211         list_add(&scheduler->n_list, &ip_vs_schedulers);
 212         mutex_unlock(&ip_vs_sched_mutex);
 213
 214         pr_info("[%s] scheduler registered.\n", scheduler->name);
 215
 216         return 0;
 217 }
 218
 219
 220 /*
 221  *  Unregister a scheduler from the scheduler list
 222  */
 223 int unregister_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
 224 {
 225         if (!scheduler) {
 226                 pr_err("%s(): NULL arg\n", __func__);
 227                 return -EINVAL;
 228         }
 229
 230         mutex_lock(&ip_vs_sched_mutex);
 231         if (list_empty(&scheduler->n_list)) {
 232                 mutex_unlock(&ip_vs_sched_mutex);
 233                 pr_err("%s(): [%s] scheduler is not in the list. failed\n",
 234                        __func__, scheduler->name);
 235                 return -EINVAL;
 236         }
 237
 238         /*
 239          *      Remove it from the d-linked scheduler list
 240          */
 241         list_del(&scheduler->n_list);
 242         mutex_unlock(&ip_vs_sched_mutex);
 243
 244         /* decrease the module use count */
 245         ip_vs_use_count_dec();
 246
 247         pr_info("[%s] scheduler unregistered.\n", scheduler->name);
 248
 249         return 0;
 250 }