net/netfilter/ipvs/ip_vs_pe.c

   1 #define KMSG_COMPONENT "IPVS"
   2 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
   3
   4 #include <linux/module.h>
   5 #include <linux/spinlock.h>
   6 #include <linux/interrupt.h>
   7 #include <asm/string.h>
   8 #include <linux/kmod.h>
   9 #include <linux/sysctl.h>
  10
  11 #include <net/ip_vs.h>
  12
  13 /* IPVS pe list */
  14 static LIST_HEAD(ip_vs_pe);
  15
  16 /* semaphore for IPVS PEs. */
  17 static DEFINE_MUTEX(ip_vs_pe_mutex);
  18
  19 /* Bind a service with a pe */
  20 void ip_vs_bind_pe(struct ip_vs_service *svc, struct ip_vs_pe *pe)
  21 {
  22         svc->pe = pe;
  23 }
  24
  25 /* Unbind a service from its pe */
  26 void ip_vs_unbind_pe(struct ip_vs_service *svc)
  27 {
  28         svc->pe = NULL;
  29 }
  30
  31 /* Get pe in the pe list by name */
  32 struct ip_vs_pe *__ip_vs_pe_getbyname(const char *pe_name)
  33 {
  34         struct ip_vs_pe *pe;
  35
  36         IP_VS_DBG(10, "%s(): pe_name \"%s\"\n", __func__,
  37                   pe_name);
  38
  39         rcu_read_lock();
  40         list_for_each_entry_rcu(pe, &ip_vs_pe, n_list) {
  41                 /* Test and get the modules atomically */
  42                 if (pe->module &&
  43                     !try_module_get(pe->module)) {
  44                         /* This pe is just deleted */
  45                         continue;
  46                 }
  47                 if (strcmp(pe_name, pe->name)==0) {
  48                         /* HIT */
  49                         rcu_read_unlock();
  50                         return pe;
  51                 }
  52                 if (pe->module)
  53                         module_put(pe->module);
  54         }
  55         rcu_read_unlock();
  56
  57         return NULL;
  58 }
  59
  60 /* Lookup pe and try to load it if it doesn't exist */
  61 struct ip_vs_pe *ip_vs_pe_getbyname(const char *name)
  62 {
  63         struct ip_vs_pe *pe;
  64
  65         /* Search for the pe by name */
  66         pe = __ip_vs_pe_getbyname(name);
  67
  68         /* If pe not found, load the module and search again */
  69         if (!pe) {
  70                 request_module("ip_vs_pe_%s", name);
  71                 pe = __ip_vs_pe_getbyname(name);
  72         }
  73
  74         return pe;
  75 }
  76
  77 /* Register a pe in the pe list */
  78 int register_ip_vs_pe(struct ip_vs_pe *pe)
  79 {
  80         struct ip_vs_pe *tmp;
  81
  82         /* increase the module use count */
  83         ip_vs_use_count_inc();
  84
  85         mutex_lock(&ip_vs_pe_mutex);
  86         /* Make sure that the pe with this name doesn't exist
  87          * in the pe list.
  88          */
  89         list_for_each_entry(tmp, &ip_vs_pe, n_list) {
  90                 if (strcmp(tmp->name, pe->name) == 0) {
  91                         mutex_unlock(&ip_vs_pe_mutex);
  92                         ip_vs_use_count_dec();
  93                         pr_err("%s(): [%s] pe already existed "
  94                                "in the system\n", __func__, pe->name);
  95                         return -EINVAL;
  96                 }
  97         }
  98         /* Add it into the d-linked pe list */
  99         list_add_rcu(&pe->n_list, &ip_vs_pe);
 100         mutex_unlock(&ip_vs_pe_mutex);
 101
 102         pr_info("[%s] pe registered.\n", pe->name);
 103
 104         return 0;
 105 }
 106 EXPORT_SYMBOL_GPL(register_ip_vs_pe);
 107
 108 /* Unregister a pe from the pe list */
 109 int unregister_ip_vs_pe(struct ip_vs_pe *pe)
 110 {
 111         mutex_lock(&ip_vs_pe_mutex);
 112         /* Remove it from the d-linked pe list */
 113         list_del_rcu(&pe->n_list);
 114         mutex_unlock(&ip_vs_pe_mutex);
 115
 116         /* decrease the module use count */
 117         ip_vs_use_count_dec();
 118
 119         pr_info("[%s] pe unregistered.\n", pe->name);
 120
 121         return 0;
 122 }
 123 EXPORT_SYMBOL_GPL(unregister_ip_vs_pe);