LXR linux/net/llc/llc

   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
  25LIST_HEAD(llc_sap_list);
  26static DEFINE_SPINLOCK(llc_sap_list_lock);
  27
  28/**
  29 *      llc_sap_alloc - allocates and initializes sap.
  30 *
  31 *      Allocates and initializes sap.
  32 */
  33static 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                refcount_set(&sap->refcnt, 1);
  45        }
  46        return sap;
  47}
  48
  49static 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;
  57out:
  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 */
  70struct 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 */
  91struct 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);
 108out:
 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 */
 122void 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
 135static struct packet_type llc_packet_type __read_mostly = {
 136        .type = cpu_to_be16(ETH_P_802_2),
 137        .func = llc_rcv,
 138};
 139
 140static 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
 145static 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
 152static void __exit llc_exit(void)
 153{
 154        dev_remove_pack(&llc_packet_type);
 155        dev_remove_pack(&llc_tr_packet_type);
 156}
 157
 158module_init(llc_init);
 159module_exit(llc_exit);
 160
 161EXPORT_SYMBOL(llc_sap_list);
 162EXPORT_SYMBOL(llc_sap_find);
 163EXPORT_SYMBOL(llc_sap_open);
 164EXPORT_SYMBOL(llc_sap_close);
 165
 166MODULE_LICENSE("GPL");
 167MODULE_AUTHOR("Procom 1997, Jay Schullist 2001, Arnaldo C. Melo 2001-2003");
 168MODULE_DESCRIPTION("LLC IEEE 802.2 core support");
 169