net/ipv4/multipath.c

   1 /* multipath.c: IPV4 multipath algorithm support.
   2  *
   3  * Copyright (C) 2004, 2005 Einar Lueck <elueck@de.ibm.com>
   4  * Copyright (C) 2005 David S. Miller <davem@davemloft.net>
   5  */
   6
   7 #include <linux/module.h>
   8 #include <linux/errno.h>
   9 #include <linux/netdevice.h>
  10 #include <linux/spinlock.h>
  11
  12 #include <net/ip_mp_alg.h>
  13
  14 static DEFINE_SPINLOCK(alg_table_lock);
  15 struct ip_mp_alg_ops *ip_mp_alg_table[IP_MP_ALG_MAX + 1];
  16
  17 int multipath_alg_register(struct ip_mp_alg_ops *ops, enum ip_mp_alg n)
  18 {
  19         struct ip_mp_alg_ops **slot;
  20         int err;
  21
  22         if (n < IP_MP_ALG_NONE || n > IP_MP_ALG_MAX ||
  23             !ops->mp_alg_select_route)
  24                 return -EINVAL;
  25
  26         spin_lock(&alg_table_lock);
  27         slot = &ip_mp_alg_table[n];
  28         if (*slot != NULL) {
  29                 err = -EBUSY;
  30         } else {
  31                 *slot = ops;
  32                 err = 0;
  33         }
  34         spin_unlock(&alg_table_lock);
  35
  36         return err;
  37 }
  38 EXPORT_SYMBOL(multipath_alg_register);
  39
  40 void multipath_alg_unregister(struct ip_mp_alg_ops *ops, enum ip_mp_alg n)
  41 {
  42         struct ip_mp_alg_ops **slot;
  43
  44         if (n < IP_MP_ALG_NONE || n > IP_MP_ALG_MAX)
  45                 return;
  46
  47         spin_lock(&alg_table_lock);
  48         slot = &ip_mp_alg_table[n];
  49         if (*slot == ops)
  50                 *slot = NULL;
  51         spin_unlock(&alg_table_lock);
  52
  53         synchronize_net();
  54 }
  55 EXPORT_SYMBOL(multipath_alg_unregister);