blob: 39cf9b9bd673cdd0d46aed0c970ca58cccbedc88 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* dummy.c: a dummy net driver
2
3 The purpose of this driver is to provide a device to point a
4 route through, but not to actually transmit packets.
5
6 Why? If you have a machine whose only connection is an occasional
7 PPP/SLIP/PLIP link, you can only connect to your own hostname
8 when the link is up. Otherwise you have to use localhost.
9 This isn't very consistent.
10
11 One solution is to set up a dummy link using PPP/SLIP/PLIP,
12 but this seems (to me) too much overhead for too little gain.
13 This driver provides a small alternative. Thus you can do
Jeff Garzik6aa20a22006-09-13 13:24:59 -040014
Linus Torvalds1da177e2005-04-16 15:20:36 -070015 [when not running slip]
16 ifconfig dummy slip.addr.ess.here up
17 [to go to slip]
18 ifconfig dummy down
19 dip whatever
20
21 This was written by looking at Donald Becker's skeleton driver
22 and the loopback driver. I then threw away anything that didn't
23 apply! Thanks to Alan Cox for the key clue on what to do with
24 misguided packets.
25
26 Nick Holloway, 27th May 1994
27 [I tweaked this explanation a little but that's all]
28 Alan Cox, 30th May 1994
29*/
30
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#include <linux/module.h>
32#include <linux/kernel.h>
33#include <linux/netdevice.h>
34#include <linux/etherdevice.h>
35#include <linux/init.h>
36#include <linux/moduleparam.h>
Patrick McHardy206c9fb2007-06-13 12:04:20 -070037#include <linux/rtnetlink.h>
Patrick McHardy5d5cb172007-06-13 12:04:34 -070038#include <net/rtnetlink.h>
Eric Dumazet6d81f412010-09-27 20:50:33 +000039#include <linux/u64_stats_sync.h>
Patrick McHardy206c9fb2007-06-13 12:04:20 -070040
Linus Torvalds1da177e2005-04-16 15:20:36 -070041static int numdummies = 1;
42
Linus Torvalds1da177e2005-04-16 15:20:36 -070043static int dummy_set_address(struct net_device *dev, void *p)
44{
45 struct sockaddr *sa = p;
46
Jeff Garzik6aa20a22006-09-13 13:24:59 -040047 if (!is_valid_ether_addr(sa->sa_data))
Linus Torvalds1da177e2005-04-16 15:20:36 -070048 return -EADDRNOTAVAIL;
Jeff Garzik6aa20a22006-09-13 13:24:59 -040049
Linus Torvalds1da177e2005-04-16 15:20:36 -070050 memcpy(dev->dev_addr, sa->sa_data, ETH_ALEN);
51 return 0;
52}
53
54/* fake multicast ability */
55static void set_multicast_list(struct net_device *dev)
56{
57}
58
Eric Dumazet6d81f412010-09-27 20:50:33 +000059struct pcpu_dstats {
60 u64 tx_packets;
61 u64 tx_bytes;
62 struct u64_stats_sync syncp;
63};
64
65static struct rtnl_link_stats64 *dummy_get_stats64(struct net_device *dev,
66 struct rtnl_link_stats64 *stats)
67{
68 int i;
69
70 for_each_possible_cpu(i) {
71 const struct pcpu_dstats *dstats;
72 u64 tbytes, tpackets;
73 unsigned int start;
74
75 dstats = per_cpu_ptr(dev->dstats, i);
76 do {
77 start = u64_stats_fetch_begin(&dstats->syncp);
78 tbytes = dstats->tx_bytes;
79 tpackets = dstats->tx_packets;
80 } while (u64_stats_fetch_retry(&dstats->syncp, start));
81 stats->tx_bytes += tbytes;
82 stats->tx_packets += tpackets;
83 }
84 return stats;
85}
Stephen Hemminger424efe92009-08-31 19:50:51 +000086
87static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev)
88{
Eric Dumazet6d81f412010-09-27 20:50:33 +000089 struct pcpu_dstats *dstats = this_cpu_ptr(dev->dstats);
90
91 u64_stats_update_begin(&dstats->syncp);
92 dstats->tx_packets++;
93 dstats->tx_bytes += skb->len;
94 u64_stats_update_end(&dstats->syncp);
Stephen Hemminger424efe92009-08-31 19:50:51 +000095
96 dev_kfree_skb(skb);
97 return NETDEV_TX_OK;
98}
99
Eric Dumazet6d81f412010-09-27 20:50:33 +0000100static int dummy_dev_init(struct net_device *dev)
101{
102 dev->dstats = alloc_percpu(struct pcpu_dstats);
103 if (!dev->dstats)
104 return -ENOMEM;
105
106 return 0;
107}
108
109static void dummy_dev_free(struct net_device *dev)
110{
111 free_percpu(dev->dstats);
112 free_netdev(dev);
113}
114
Stephen Hemmingeraa18e9e2008-11-20 20:28:00 -0800115static const struct net_device_ops dummy_netdev_ops = {
Eric Dumazet6d81f412010-09-27 20:50:33 +0000116 .ndo_init = dummy_dev_init,
Stephen Hemmingeraa18e9e2008-11-20 20:28:00 -0800117 .ndo_start_xmit = dummy_xmit,
118 .ndo_validate_addr = eth_validate_addr,
119 .ndo_set_multicast_list = set_multicast_list,
120 .ndo_set_mac_address = dummy_set_address,
Eric Dumazet6d81f412010-09-27 20:50:33 +0000121 .ndo_get_stats64 = dummy_get_stats64,
Stephen Hemmingeraa18e9e2008-11-20 20:28:00 -0800122};
123
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700124static void dummy_setup(struct net_device *dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125{
Stephen Hemmingeraa18e9e2008-11-20 20:28:00 -0800126 ether_setup(dev);
127
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 /* Initialize the device structure. */
Stephen Hemmingeraa18e9e2008-11-20 20:28:00 -0800129 dev->netdev_ops = &dummy_netdev_ops;
Eric Dumazet6d81f412010-09-27 20:50:33 +0000130 dev->destructor = dummy_dev_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131
132 /* Fill in device structure with ethernet-generic values. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 dev->tx_queue_len = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 dev->flags |= IFF_NOARP;
135 dev->flags &= ~IFF_MULTICAST;
Eric Dumazet6d81f412010-09-27 20:50:33 +0000136 dev->features |= NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_TSO;
137 dev->features |= NETIF_F_NO_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 random_ether_addr(dev->dev_addr);
139}
Eric Dumazet6d81f412010-09-27 20:50:33 +0000140
Patrick McHardy0e068772007-07-11 19:42:31 -0700141static int dummy_validate(struct nlattr *tb[], struct nlattr *data[])
142{
143 if (tb[IFLA_ADDRESS]) {
144 if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
145 return -EINVAL;
146 if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
147 return -EADDRNOTAVAIL;
148 }
149 return 0;
150}
151
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700152static struct rtnl_link_ops dummy_link_ops __read_mostly = {
153 .kind = "dummy",
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700154 .setup = dummy_setup,
Patrick McHardy0e068772007-07-11 19:42:31 -0700155 .validate = dummy_validate,
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700156};
157
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158/* Number of dummy devices to be set up by this module. */
159module_param(numdummies, int, 0);
160MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices");
161
Patrick McHardy206c9fb2007-06-13 12:04:20 -0700162static int __init dummy_init_one(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163{
164 struct net_device *dev_dummy;
165 int err;
166
Patrick McHardy2d85cba2007-07-11 19:42:13 -0700167 dev_dummy = alloc_netdev(0, "dummy%d", dummy_setup);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 if (!dev_dummy)
169 return -ENOMEM;
170
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700171 dev_dummy->rtnl_link_ops = &dummy_link_ops;
172 err = register_netdevice(dev_dummy);
173 if (err < 0)
174 goto err;
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700175 return 0;
176
177err:
178 free_netdev(dev_dummy);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 return err;
180}
181
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182static int __init dummy_init_module(void)
Jeff Garzik6aa20a22006-09-13 13:24:59 -0400183{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 int i, err = 0;
Patrick McHardy206c9fb2007-06-13 12:04:20 -0700185
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700186 rtnl_lock();
187 err = __rtnl_link_register(&dummy_link_ops);
188
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 for (i = 0; i < numdummies && !err; i++)
Patrick McHardy206c9fb2007-06-13 12:04:20 -0700190 err = dummy_init_one();
Patrick McHardy2d85cba2007-07-11 19:42:13 -0700191 if (err < 0)
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700192 __rtnl_link_unregister(&dummy_link_ops);
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700193 rtnl_unlock();
194
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 return err;
Jeff Garzik6aa20a22006-09-13 13:24:59 -0400196}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197
198static void __exit dummy_cleanup_module(void)
199{
Patrick McHardy2d85cba2007-07-11 19:42:13 -0700200 rtnl_link_unregister(&dummy_link_ops);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201}
202
203module_init(dummy_init_module);
204module_exit(dummy_cleanup_module);
205MODULE_LICENSE("GPL");
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700206MODULE_ALIAS_RTNL_LINK("dummy");