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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   */
llc_sap_alloc(void)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  		refcount_set(&sap->refcnt, 1);
45  	}
46  	return sap;
47  }
48  
__llc_sap_find(unsigned char sap_value)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   */
llc_sap_find(unsigned char sap_value)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   */
llc_sap_open(unsigned char lsap,int (* func)(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt,struct net_device * orig_dev))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   */
llc_sap_close(struct llc_sap * sap)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  	kfree_rcu(sap, rcu);
131  }
132  
133  static struct packet_type llc_packet_type __read_mostly = {
134  	.type = cpu_to_be16(ETH_P_802_2),
135  	.func = llc_rcv,
136  };
137  
llc_init(void)138  static int __init llc_init(void)
139  {
140  	dev_add_pack(&llc_packet_type);
141  	return 0;
142  }
143  
llc_exit(void)144  static void __exit llc_exit(void)
145  {
146  	dev_remove_pack(&llc_packet_type);
147  }
148  
149  module_init(llc_init);
150  module_exit(llc_exit);
151  
152  EXPORT_SYMBOL(llc_sap_list);
153  EXPORT_SYMBOL(llc_sap_find);
154  EXPORT_SYMBOL(llc_sap_open);
155  EXPORT_SYMBOL(llc_sap_close);
156  
157  MODULE_LICENSE("GPL");
158  MODULE_AUTHOR("Procom 1997, Jay Schullist 2001, Arnaldo C. Melo 2001-2003");
159  MODULE_DESCRIPTION("LLC IEEE 802.2 core support");
160