xref: /openbmc/linux/net/llc/llc_core.c (revision f1f34a51)
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 - searches a SAP in station
63  *	@sap_value: sap to be found
64  *
65  *	Searches 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