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 /* Get pe in the pe list by name */
  20 struct ip_vs_pe *__ip_vs_pe_getbyname(const char *pe_name)
  21 {
  22         struct ip_vs_pe *pe;
  23
  24         IP_VS_DBG(10, "%s(): pe_name \"%s\"\n", __func__,
  25                   pe_name);
  26
  27         rcu_read_lock();
  28         list_for_each_entry_rcu(pe, &ip_vs_pe, n_list) {
  29                 /* Test and get the modules atomically */
  30                 if (pe->module &&
  31                     !try_module_get(pe->module)) {
  32                         /* This pe is just deleted */
  33                         continue;
  34                 }
  35                 if (strcmp(pe_name, pe->name)==0) {
  36                         /* HIT */
  37                         rcu_read_unlock();
  38                         return pe;
  39                 }
  40                 if (pe->module)
  41                         module_put(pe->module);
  42         }
  43         rcu_read_unlock();
  44
  45         return NULL;
  46 }
  47
  48 /* Lookup pe and try to load it if it doesn't exist */
  49 struct ip_vs_pe *ip_vs_pe_getbyname(const char *name)
  50 {
  51         struct ip_vs_pe *pe;
  52
  53         /* Search for the pe by name */
  54         pe = __ip_vs_pe_getbyname(name);
  55
  56         /* If pe not found, load the module and search again */
  57         if (!pe) {
  58                 request_module("ip_vs_pe_%s", name);
  59                 pe = __ip_vs_pe_getbyname(name);
  60         }
  61
  62         return pe;
  63 }
  64
  65 /* Register a pe in the pe list */
  66 int register_ip_vs_pe(struct ip_vs_pe *pe)
  67 {
  68         struct ip_vs_pe *tmp;
  69
  70         /* increase the module use count */
  71         ip_vs_use_count_inc();
  72
  73         mutex_lock(&ip_vs_pe_mutex);
  74         /* Make sure that the pe with this name doesn't exist
  75          * in the pe list.
  76          */
  77         list_for_each_entry(tmp, &ip_vs_pe, n_list) {
  78                 if (strcmp(tmp->name, pe->name) == 0) {
  79                         mutex_unlock(&ip_vs_pe_mutex);
  80                         ip_vs_use_count_dec();
  81                         pr_err("%s(): [%s] pe already existed "
  82                                "in the system\n", __func__, pe->name);
  83                         return -EINVAL;
  84                 }
  85         }
  86         /* Add it into the d-linked pe list */
  87         list_add_rcu(&pe->n_list, &ip_vs_pe);
  88         mutex_unlock(&ip_vs_pe_mutex);
  89
  90         pr_info("[%s] pe registered.\n", pe->name);
  91
  92         return 0;
  93 }
  94 EXPORT_SYMBOL_GPL(register_ip_vs_pe);
  95
  96 /* Unregister a pe from the pe list */
  97 int unregister_ip_vs_pe(struct ip_vs_pe *pe)
  98 {
  99         mutex_lock(&ip_vs_pe_mutex);
 100         /* Remove it from the d-linked pe list */
 101         list_del_rcu(&pe->n_list);
 102         mutex_unlock(&ip_vs_pe_mutex);
 103
 104         /* decrease the module use count */
 105         ip_vs_use_count_dec();
 106
 107         pr_info("[%s] pe unregistered.\n", pe->name);
 108
 109         return 0;
 110 }
 111 EXPORT_SYMBOL_GPL(unregister_ip_vs_pe);