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 DEFINE_RWLOCK(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
  37         if (sap) {
  38                 /* sap->laddr.mac - leave as a null, it's filled by bind */
  39                 sap->state = LLC_SAP_STATE_ACTIVE;
  40                 rwlock_init(&sap->sk_list.lock);
  41                 atomic_set(&sap->refcnt, 1);
  42         }
  43         return sap;
  44 }
  45
  46 /**
  47  *      llc_add_sap - add sap to station list
  48  *      @sap: Address of the sap
  49  *
  50  *      Adds a sap to the LLC's station sap list.
  51  */
  52 static void llc_add_sap(struct llc_sap *sap)
  53 {
  54         list_add_tail(&sap->node, &llc_sap_list);
  55 }
  56
  57 /**
  58  *      llc_del_sap - del sap from station list
  59  *      @sap: Address of the sap
  60  *
  61  *      Removes a sap to the LLC's station sap list.
  62  */
  63 static void llc_del_sap(struct llc_sap *sap)
  64 {
  65         write_lock_bh(&llc_sap_list_lock);
  66         list_del(&sap->node);
  67         write_unlock_bh(&llc_sap_list_lock);
  68 }
  69
  70 static struct llc_sap *__llc_sap_find(unsigned char sap_value)
  71 {
  72         struct llc_sap* sap;
  73
  74         list_for_each_entry(sap, &llc_sap_list, node)
  75                 if (sap->laddr.lsap == sap_value)
  76                         goto out;
  77         sap = NULL;
  78 out:
  79         return sap;
  80 }
  81
  82 /**
  83  *      llc_sap_find - searchs a SAP in station
  84  *      @sap_value: sap to be found
  85  *
  86  *      Searchs for a sap in the sap list of the LLC's station upon the sap ID.
  87  *      If the sap is found it will be refcounted and the user will have to do
  88  *      a llc_sap_put after use.
  89  *      Returns the sap or %NULL if not found.
  90  */
  91 struct llc_sap *llc_sap_find(unsigned char sap_value)
  92 {
  93         struct llc_sap* sap;
  94
  95         read_lock_bh(&llc_sap_list_lock);
  96         sap = __llc_sap_find(sap_value);
  97         if (sap)
  98                 llc_sap_hold(sap);
  99         read_unlock_bh(&llc_sap_list_lock);
 100         return sap;
 101 }
 102
 103 /**
 104  *      llc_sap_open - open interface to the upper layers.
 105  *      @lsap: SAP number.
 106  *      @func: rcv func for datalink protos
 107  *
 108  *      Interface function to upper layer. Each one who wants to get a SAP
 109  *      (for example NetBEUI) should call this function. Returns the opened
 110  *      SAP for success, NULL for failure.
 111  */
 112 struct llc_sap *llc_sap_open(unsigned char lsap,
 113                              int (*func)(struct sk_buff *skb,
 114                                          struct net_device *dev,
 115                                          struct packet_type *pt,
 116                                          struct net_device *orig_dev))
 117 {
 118         struct llc_sap *sap = NULL;
 119
 120         write_lock_bh(&llc_sap_list_lock);
 121         if (__llc_sap_find(lsap)) /* SAP already exists */
 122                 goto out;
 123         sap = llc_sap_alloc();
 124         if (!sap)
 125                 goto out;
 126         sap->laddr.lsap = lsap;
 127         sap->rcv_func   = func;
 128         llc_add_sap(sap);
 129 out:
 130         write_unlock_bh(&llc_sap_list_lock);
 131         return sap;
 132 }
 133
 134 /**
 135  *      llc_sap_close - close interface for upper layers.
 136  *      @sap: SAP to be closed.
 137  *
 138  *      Close interface function to upper layer. Each one who wants to
 139  *      close an open SAP (for example NetBEUI) should call this function.
 140  *      Removes this sap from the list of saps in the station and then
 141  *      frees the memory for this sap.
 142  */
 143 void llc_sap_close(struct llc_sap *sap)
 144 {
 145         WARN_ON(!hlist_empty(&sap->sk_list.list));
 146         llc_del_sap(sap);
 147         kfree(sap);
 148 }
 149
 150 static struct packet_type llc_packet_type __read_mostly = {
 151         .type = cpu_to_be16(ETH_P_802_2),
 152         .func = llc_rcv,
 153 };
 154
 155 static struct packet_type llc_tr_packet_type __read_mostly = {
 156         .type = cpu_to_be16(ETH_P_TR_802_2),
 157         .func = llc_rcv,
 158 };
 159
 160 static int __init llc_init(void)
 161 {
 162         struct net_device *dev;
 163
 164         dev = first_net_device(&init_net);
 165         if (dev != NULL)
 166                 dev = next_net_device(dev);
 167
 168         dev_add_pack(&llc_packet_type);
 169         dev_add_pack(&llc_tr_packet_type);
 170         return 0;
 171 }
 172
 173 static void __exit llc_exit(void)
 174 {
 175         dev_remove_pack(&llc_packet_type);
 176         dev_remove_pack(&llc_tr_packet_type);
 177 }
 178
 179 module_init(llc_init);
 180 module_exit(llc_exit);
 181
 182 EXPORT_SYMBOL(llc_sap_list);
 183 EXPORT_SYMBOL(llc_sap_list_lock);
 184 EXPORT_SYMBOL(llc_sap_find);
 185 EXPORT_SYMBOL(llc_sap_open);
 186 EXPORT_SYMBOL(llc_sap_close);
 187
 188 MODULE_LICENSE("GPL");
 189 MODULE_AUTHOR("Procom 1997, Jay Schullist 2001, Arnaldo C. Melo 2001-2003");
 190 MODULE_DESCRIPTION("LLC IEEE 802.2 core support");