Linux 2.6.38-rc1
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / net / 802 / stp.c
blob978c30b1b36b5a138eeeb7b9780009686f356d6e
1 /*
2 * STP SAP demux
4 * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * version 2 as published by the Free Software Foundation.
9 */
10 #include <linux/mutex.h>
11 #include <linux/skbuff.h>
12 #include <linux/etherdevice.h>
13 #include <linux/llc.h>
14 #include <linux/slab.h>
15 #include <net/llc.h>
16 #include <net/llc_pdu.h>
17 #include <net/stp.h>
19 /* 01:80:c2:00:00:20 - 01:80:c2:00:00:2F */
20 #define GARP_ADDR_MIN 0x20
21 #define GARP_ADDR_MAX 0x2F
22 #define GARP_ADDR_RANGE (GARP_ADDR_MAX - GARP_ADDR_MIN)
24 static const struct stp_proto __rcu *garp_protos[GARP_ADDR_RANGE + 1] __read_mostly;
25 static const struct stp_proto __rcu *stp_proto __read_mostly;
27 static struct llc_sap *sap __read_mostly;
28 static unsigned int sap_registered;
29 static DEFINE_MUTEX(stp_proto_mutex);
31 /* Called under rcu_read_lock from LLC */
32 static int stp_pdu_rcv(struct sk_buff *skb, struct net_device *dev,
33 struct packet_type *pt, struct net_device *orig_dev)
35 const struct ethhdr *eh = eth_hdr(skb);
36 const struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
37 const struct stp_proto *proto;
39 if (pdu->ssap != LLC_SAP_BSPAN ||
40 pdu->dsap != LLC_SAP_BSPAN ||
41 pdu->ctrl_1 != LLC_PDU_TYPE_U)
42 goto err;
44 if (eh->h_dest[5] >= GARP_ADDR_MIN && eh->h_dest[5] <= GARP_ADDR_MAX) {
45 proto = rcu_dereference(garp_protos[eh->h_dest[5] -
46 GARP_ADDR_MIN]);
47 if (proto &&
48 compare_ether_addr(eh->h_dest, proto->group_address))
49 goto err;
50 } else
51 proto = rcu_dereference(stp_proto);
53 if (!proto)
54 goto err;
56 proto->rcv(proto, skb, dev);
57 return 0;
59 err:
60 kfree_skb(skb);
61 return 0;
64 int stp_proto_register(const struct stp_proto *proto)
66 int err = 0;
68 mutex_lock(&stp_proto_mutex);
69 if (sap_registered++ == 0) {
70 sap = llc_sap_open(LLC_SAP_BSPAN, stp_pdu_rcv);
71 if (!sap) {
72 err = -ENOMEM;
73 goto out;
76 if (is_zero_ether_addr(proto->group_address))
77 rcu_assign_pointer(stp_proto, proto);
78 else
79 rcu_assign_pointer(garp_protos[proto->group_address[5] -
80 GARP_ADDR_MIN], proto);
81 out:
82 mutex_unlock(&stp_proto_mutex);
83 return err;
85 EXPORT_SYMBOL_GPL(stp_proto_register);
87 void stp_proto_unregister(const struct stp_proto *proto)
89 mutex_lock(&stp_proto_mutex);
90 if (is_zero_ether_addr(proto->group_address))
91 rcu_assign_pointer(stp_proto, NULL);
92 else
93 rcu_assign_pointer(garp_protos[proto->group_address[5] -
94 GARP_ADDR_MIN], NULL);
95 synchronize_rcu();
97 if (--sap_registered == 0)
98 llc_sap_put(sap);
99 mutex_unlock(&stp_proto_mutex);
101 EXPORT_SYMBOL_GPL(stp_proto_unregister);
103 MODULE_LICENSE("GPL");