perf_event: x86: Fixup constraints typing issue
[linux-2.6.git] / net / 802 / stp.c
1 /*
2  *      STP SAP demux
3  *
4  *      Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
5  *
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 <net/llc.h>
15 #include <net/llc_pdu.h>
16 #include <net/stp.h>
17
18 /* 01:80:c2:00:00:20 - 01:80:c2:00:00:2F */
19 #define GARP_ADDR_MIN   0x20
20 #define GARP_ADDR_MAX   0x2F
21 #define GARP_ADDR_RANGE (GARP_ADDR_MAX - GARP_ADDR_MIN)
22
23 static const struct stp_proto *garp_protos[GARP_ADDR_RANGE + 1] __read_mostly;
24 static const struct stp_proto *stp_proto __read_mostly;
25
26 static struct llc_sap *sap __read_mostly;
27 static unsigned int sap_registered;
28 static DEFINE_MUTEX(stp_proto_mutex);
29
30 /* Called under rcu_read_lock from LLC */
31 static int stp_pdu_rcv(struct sk_buff *skb, struct net_device *dev,
32                        struct packet_type *pt, struct net_device *orig_dev)
33 {
34         const struct ethhdr *eh = eth_hdr(skb);
35         const struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
36         const struct stp_proto *proto;
37
38         if (pdu->ssap != LLC_SAP_BSPAN ||
39             pdu->dsap != LLC_SAP_BSPAN ||
40             pdu->ctrl_1 != LLC_PDU_TYPE_U)
41                 goto err;
42
43         if (eh->h_dest[5] >= GARP_ADDR_MIN && eh->h_dest[5] <= GARP_ADDR_MAX) {
44                 proto = rcu_dereference(garp_protos[eh->h_dest[5] -
45                                                     GARP_ADDR_MIN]);
46                 if (proto &&
47                     compare_ether_addr(eh->h_dest, proto->group_address))
48                         goto err;
49         } else
50                 proto = rcu_dereference(stp_proto);
51
52         if (!proto)
53                 goto err;
54
55         proto->rcv(proto, skb, dev);
56         return 0;
57
58 err:
59         kfree_skb(skb);
60         return 0;
61 }
62
63 int stp_proto_register(const struct stp_proto *proto)
64 {
65         int err = 0;
66
67         mutex_lock(&stp_proto_mutex);
68         if (sap_registered++ == 0) {
69                 sap = llc_sap_open(LLC_SAP_BSPAN, stp_pdu_rcv);
70                 if (!sap) {
71                         err = -ENOMEM;
72                         goto out;
73                 }
74         }
75         if (is_zero_ether_addr(proto->group_address))
76                 rcu_assign_pointer(stp_proto, proto);
77         else
78                 rcu_assign_pointer(garp_protos[proto->group_address[5] -
79                                                GARP_ADDR_MIN], proto);
80 out:
81         mutex_unlock(&stp_proto_mutex);
82         return err;
83 }
84 EXPORT_SYMBOL_GPL(stp_proto_register);
85
86 void stp_proto_unregister(const struct stp_proto *proto)
87 {
88         mutex_lock(&stp_proto_mutex);
89         if (is_zero_ether_addr(proto->group_address))
90                 rcu_assign_pointer(stp_proto, NULL);
91         else
92                 rcu_assign_pointer(garp_protos[proto->group_address[5] -
93                                                GARP_ADDR_MIN], NULL);
94         synchronize_rcu();
95
96         if (--sap_registered == 0)
97                 llc_sap_put(sap);
98         mutex_unlock(&stp_proto_mutex);
99 }
100 EXPORT_SYMBOL_GPL(stp_proto_unregister);
101
102 MODULE_LICENSE("GPL");