uml: SMP locking commentary
[linux-2.6] / arch / um / drivers / mcast_kern.c
1 /*
2  * user-mode-linux networking multicast transport
3  * Copyright (C) 2001 by Harald Welte <laforge@gnumonks.org>
4  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
5  *
6  * based on the existing uml-networking code, which is
7  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
8  * James Leu (jleu@mindspring.net).
9  * Copyright (C) 2001 by various other people who didn't put their name here.
10  *
11  * Licensed under the GPL.
12  */
13
14 #include "linux/init.h"
15 #include <linux/netdevice.h>
16 #include "mcast.h"
17 #include "net_kern.h"
18
19 struct mcast_init {
20         char *addr;
21         int port;
22         int ttl;
23 };
24
25 static void mcast_init(struct net_device *dev, void *data)
26 {
27         struct uml_net_private *pri;
28         struct mcast_data *dpri;
29         struct mcast_init *init = data;
30
31         pri = dev->priv;
32         dpri = (struct mcast_data *) pri->user;
33         dpri->addr = init->addr;
34         dpri->port = init->port;
35         dpri->ttl = init->ttl;
36         dpri->dev = dev;
37
38         printk("mcast backend multicast address: %s:%u, TTL:%u\n",
39                dpri->addr, dpri->port, dpri->ttl);
40 }
41
42 static int mcast_read(int fd, struct sk_buff *skb, struct uml_net_private *lp)
43 {
44         return net_recvfrom(fd, skb_mac_header(skb),
45                             skb->dev->mtu + ETH_HEADER_OTHER);
46 }
47
48 static int mcast_write(int fd, struct sk_buff *skb, struct uml_net_private *lp)
49 {
50         return mcast_user_write(fd, skb->data, skb->len,
51                                 (struct mcast_data *) &lp->user);
52 }
53
54 static const struct net_kern_info mcast_kern_info = {
55         .init                   = mcast_init,
56         .protocol               = eth_protocol,
57         .read                   = mcast_read,
58         .write                  = mcast_write,
59 };
60
61 int mcast_setup(char *str, char **mac_out, void *data)
62 {
63         struct mcast_init *init = data;
64         char *port_str = NULL, *ttl_str = NULL, *remain;
65         char *last;
66
67         *init = ((struct mcast_init)
68                 { .addr         = "239.192.168.1",
69                   .port         = 1102,
70                   .ttl          = 1 });
71
72         remain = split_if_spec(str, mac_out, &init->addr, &port_str, &ttl_str,
73                                NULL);
74         if (remain != NULL) {
75                 printk(KERN_ERR "mcast_setup - Extra garbage on "
76                        "specification : '%s'\n", remain);
77                 return 0;
78         }
79
80         if (port_str != NULL) {
81                 init->port = simple_strtoul(port_str, &last, 10);
82                 if ((*last != '\0') || (last == port_str)) {
83                         printk(KERN_ERR "mcast_setup - Bad port : '%s'\n",
84                                port_str);
85                         return 0;
86                 }
87         }
88
89         if (ttl_str != NULL) {
90                 init->ttl = simple_strtoul(ttl_str, &last, 10);
91                 if ((*last != '\0') || (last == ttl_str)) {
92                         printk(KERN_ERR "mcast_setup - Bad ttl : '%s'\n",
93                                ttl_str);
94                         return 0;
95                 }
96         }
97
98         printk(KERN_INFO "Configured mcast device: %s:%u-%u\n", init->addr,
99                init->port, init->ttl);
100
101         return 1;
102 }
103
104 static struct transport mcast_transport = {
105         .list           = LIST_HEAD_INIT(mcast_transport.list),
106         .name           = "mcast",
107         .setup          = mcast_setup,
108         .user           = &mcast_user_info,
109         .kern           = &mcast_kern_info,
110         .private_size   = sizeof(struct mcast_data),
111         .setup_size     = sizeof(struct mcast_init),
112 };
113
114 static int register_mcast(void)
115 {
116         register_transport(&mcast_transport);
117         return 0;
118 }
119
120 late_initcall(register_mcast);