net/llc/llc_core.c

   1 /*
   2  * llc_core.c - Minimum needed routines for sap handling and module init/exit
   3  *
   4  * Copyright (c) 1997 by Procom Technology, Inc.
   5  *               2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   6  *
   7  * This program can be redistributed or modified under the terms of the
   8  * GNU General Public License as published by the Free Software Foundation.
   9  * This program is distributed without any warranty or implied warranty
  10  * of merchantability or fitness for a particular purpose.
  11  *
  12  * See the GNU General Public License for more details.
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/if_ether.h>
  18 #include <linux/netdevice.h>
  19 #include <linux/slab.h>
  20 #include <linux/string.h>
  21 #include <linux/init.h>
  22 #include <net/net_namespace.h>
  23 #include <net/llc.h>
  24
  25 LIST_HEAD(llc_sap_list);
  26 static DEFINE_SPINLOCK(llc_sap_list_lock);
  27
  28 /**
  29  *      llc_sap_alloc - allocates and initializes sap.
  30  *
  31  *      Allocates and initializes sap.
  32  */
  33 static struct llc_sap *llc_sap_alloc(void)
  34 {
  35         struct llc_sap *sap = kzalloc(sizeof(*sap), GFP_ATOMIC);
  36         int i;
  37
  38         if (sap) {
  39                 /* sap->laddr.mac - leave as a null, it's filled by bind */
  40                 sap->state = LLC_SAP_STATE_ACTIVE;
  41                 spin_lock_init(&sap->sk_lock);
  42                 for (i = 0; i < LLC_SK_LADDR_HASH_ENTRIES; i++)
  43                         INIT_HLIST_NULLS_HEAD(&sap->sk_laddr_hash[i], i);
  44                 atomic_set(&sap->refcnt, 1);
  45         }
  46         return sap;
  47 }
  48
  49 static struct llc_sap *__llc_sap_find(unsigned char sap_value)
  50 {
  51         struct llc_sap *sap;
  52
  53         list_for_each_entry(sap, &llc_sap_list, node)
  54                 if (sap->laddr.lsap == sap_value)
  55                         goto out;
  56         sap = NULL;
  57 out:
  58         return sap;
  59 }
  60
  61 /**
  62  *      llc_sap_find - searchs a SAP in station
  63  *      @sap_value: sap to be found
  64  *
  65  *      Searchs for a sap in the sap list of the LLC's station upon the sap ID.
  66  *      If the sap is found it will be refcounted and the user will have to do
  67  *      a llc_sap_put after use.
  68  *      Returns the sap or %NULL if not found.
  69  */
  70 struct llc_sap *llc_sap_find(unsigned char sap_value)
  71 {
  72         struct llc_sap *sap;
  73
  74         rcu_read_lock_bh();
  75         sap = __llc_sap_find(sap_value);
  76         if (!sap || !llc_sap_hold_safe(sap))
  77                 sap = NULL;
  78         rcu_read_unlock_bh();
  79         return sap;
  80 }
  81
  82 /**
  83  *      llc_sap_open - open interface to the upper layers.
  84  *      @lsap: SAP number.
  85  *      @func: rcv func for datalink protos
  86  *
  87  *      Interface function to upper layer. Each one who wants to get a SAP
  88  *      (for example NetBEUI) should call this function. Returns the opened
  89  *      SAP for success, NULL for failure.
  90  */
  91 struct llc_sap *llc_sap_open(unsigned char lsap,
  92                              int (*func)(struct sk_buff *skb,
  93                                          struct net_device *dev,
  94                                          struct packet_type *pt,
  95                                          struct net_device *orig_dev))
  96 {
  97         struct llc_sap *sap = NULL;
  98
  99         spin_lock_bh(&llc_sap_list_lock);
 100         if (__llc_sap_find(lsap)) /* SAP already exists */
 101                 goto out;
 102         sap = llc_sap_alloc();
 103         if (!sap)
 104                 goto out;
 105         sap->laddr.lsap = lsap;
 106         sap->rcv_func   = func;
 107         list_add_tail_rcu(&sap->node, &llc_sap_list);
 108 out:
 109         spin_unlock_bh(&llc_sap_list_lock);
 110         return sap;
 111 }
 112
 113 /**
 114  *      llc_sap_close - close interface for upper layers.
 115  *      @sap: SAP to be closed.
 116  *
 117  *      Close interface function to upper layer. Each one who wants to
 118  *      close an open SAP (for example NetBEUI) should call this function.
 119  *      Removes this sap from the list of saps in the station and then
 120  *      frees the memory for this sap.
 121  */
 122 void llc_sap_close(struct llc_sap *sap)
 123 {
 124         WARN_ON(sap->sk_count);
 125
 126         spin_lock_bh(&llc_sap_list_lock);
 127         list_del_rcu(&sap->node);
 128         spin_unlock_bh(&llc_sap_list_lock);
 129
 130         synchronize_rcu();
 131
 132         kfree(sap);
 133 }
 134
 135 static struct packet_type llc_packet_type __read_mostly = {
 136         .type = cpu_to_be16(ETH_P_802_2),
 137         .func = llc_rcv,
 138 };
 139
 140 static struct packet_type llc_tr_packet_type __read_mostly = {
 141         .type = cpu_to_be16(ETH_P_TR_802_2),
 142         .func = llc_rcv,
 143 };
 144
 145 static int __init llc_init(void)
 146 {
 147         dev_add_pack(&llc_packet_type);
 148         dev_add_pack(&llc_tr_packet_type);
 149         return 0;
 150 }
 151
 152 static void __exit llc_exit(void)
 153 {
 154         dev_remove_pack(&llc_packet_type);
 155         dev_remove_pack(&llc_tr_packet_type);
 156 }
 157
 158 module_init(llc_init);
 159 module_exit(llc_exit);
 160
 161 EXPORT_SYMBOL(llc_sap_list);
 162 EXPORT_SYMBOL(llc_sap_find);
 163 EXPORT_SYMBOL(llc_sap_open);
 164 EXPORT_SYMBOL(llc_sap_close);
 165
 166 MODULE_LICENSE("GPL");
 167 MODULE_AUTHOR("Procom 1997, Jay Schullist 2001, Arnaldo C. Melo 2001-2003");
 168 MODULE_DESCRIPTION("LLC IEEE 802.2 core support");