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Commit | Line | Data |
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1da177e4 LT |
1 | /* 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 | |
6aa20a22 | 14 | |
1da177e4 LT |
15 | [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 | ||
1da177e4 LT |
31 | #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> | |
206c9fb2 | 37 | #include <linux/rtnetlink.h> |
5d5cb173 | 38 | #include <net/rtnetlink.h> |
6d81f41c | 39 | #include <linux/u64_stats_sync.h> |
206c9fb2 | 40 | |
1da177e4 LT |
41 | static int numdummies = 1; |
42 | ||
1da177e4 LT |
43 | static int dummy_set_address(struct net_device *dev, void *p) |
44 | { | |
45 | struct sockaddr *sa = p; | |
46 | ||
6aa20a22 | 47 | if (!is_valid_ether_addr(sa->sa_data)) |
1da177e4 | 48 | return -EADDRNOTAVAIL; |
6aa20a22 | 49 | |
7ce5d222 | 50 | dev->addr_assign_type &= ~NET_ADDR_RANDOM; |
1da177e4 LT |
51 | memcpy(dev->dev_addr, sa->sa_data, ETH_ALEN); |
52 | return 0; | |
53 | } | |
54 | ||
55 | /* fake multicast ability */ | |
56 | static void set_multicast_list(struct net_device *dev) | |
57 | { | |
58 | } | |
59 | ||
6d81f41c ED |
60 | struct pcpu_dstats { |
61 | u64 tx_packets; | |
62 | u64 tx_bytes; | |
63 | struct u64_stats_sync syncp; | |
64 | }; | |
65 | ||
66 | static struct rtnl_link_stats64 *dummy_get_stats64(struct net_device *dev, | |
67 | struct rtnl_link_stats64 *stats) | |
68 | { | |
69 | int i; | |
70 | ||
71 | for_each_possible_cpu(i) { | |
72 | const struct pcpu_dstats *dstats; | |
73 | u64 tbytes, tpackets; | |
74 | unsigned int start; | |
75 | ||
76 | dstats = per_cpu_ptr(dev->dstats, i); | |
77 | do { | |
78 | start = u64_stats_fetch_begin(&dstats->syncp); | |
79 | tbytes = dstats->tx_bytes; | |
80 | tpackets = dstats->tx_packets; | |
81 | } while (u64_stats_fetch_retry(&dstats->syncp, start)); | |
82 | stats->tx_bytes += tbytes; | |
83 | stats->tx_packets += tpackets; | |
84 | } | |
85 | return stats; | |
86 | } | |
424efe9c SH |
87 | |
88 | static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev) | |
89 | { | |
6d81f41c ED |
90 | struct pcpu_dstats *dstats = this_cpu_ptr(dev->dstats); |
91 | ||
92 | u64_stats_update_begin(&dstats->syncp); | |
93 | dstats->tx_packets++; | |
94 | dstats->tx_bytes += skb->len; | |
95 | u64_stats_update_end(&dstats->syncp); | |
424efe9c SH |
96 | |
97 | dev_kfree_skb(skb); | |
98 | return NETDEV_TX_OK; | |
99 | } | |
100 | ||
6d81f41c ED |
101 | static int dummy_dev_init(struct net_device *dev) |
102 | { | |
103 | dev->dstats = alloc_percpu(struct pcpu_dstats); | |
104 | if (!dev->dstats) | |
105 | return -ENOMEM; | |
106 | ||
107 | return 0; | |
108 | } | |
109 | ||
890fdf2a | 110 | static void dummy_dev_uninit(struct net_device *dev) |
6d81f41c ED |
111 | { |
112 | free_percpu(dev->dstats); | |
6d81f41c ED |
113 | } |
114 | ||
aa18e9e8 | 115 | static const struct net_device_ops dummy_netdev_ops = { |
6d81f41c | 116 | .ndo_init = dummy_dev_init, |
890fdf2a | 117 | .ndo_uninit = dummy_dev_uninit, |
aa18e9e8 SH |
118 | .ndo_start_xmit = dummy_xmit, |
119 | .ndo_validate_addr = eth_validate_addr, | |
afc4b13d | 120 | .ndo_set_rx_mode = set_multicast_list, |
aa18e9e8 | 121 | .ndo_set_mac_address = dummy_set_address, |
6d81f41c | 122 | .ndo_get_stats64 = dummy_get_stats64, |
aa18e9e8 SH |
123 | }; |
124 | ||
5d5cb173 | 125 | static void dummy_setup(struct net_device *dev) |
1da177e4 | 126 | { |
aa18e9e8 SH |
127 | ether_setup(dev); |
128 | ||
1da177e4 | 129 | /* Initialize the device structure. */ |
aa18e9e8 | 130 | dev->netdev_ops = &dummy_netdev_ops; |
890fdf2a | 131 | dev->destructor = free_netdev; |
1da177e4 LT |
132 | |
133 | /* Fill in device structure with ethernet-generic values. */ | |
1da177e4 | 134 | dev->tx_queue_len = 0; |
1da177e4 LT |
135 | dev->flags |= IFF_NOARP; |
136 | dev->flags &= ~IFF_MULTICAST; | |
6d81f41c | 137 | dev->features |= NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_TSO; |
34324dc2 | 138 | dev->features |= NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX; |
7ce5d222 | 139 | eth_hw_addr_random(dev); |
1da177e4 | 140 | } |
6d81f41c | 141 | |
0e06877c PM |
142 | static int dummy_validate(struct nlattr *tb[], struct nlattr *data[]) |
143 | { | |
144 | if (tb[IFLA_ADDRESS]) { | |
145 | if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN) | |
146 | return -EINVAL; | |
147 | if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS]))) | |
148 | return -EADDRNOTAVAIL; | |
149 | } | |
150 | return 0; | |
151 | } | |
152 | ||
5d5cb173 PM |
153 | static struct rtnl_link_ops dummy_link_ops __read_mostly = { |
154 | .kind = "dummy", | |
5d5cb173 | 155 | .setup = dummy_setup, |
0e06877c | 156 | .validate = dummy_validate, |
5d5cb173 PM |
157 | }; |
158 | ||
1da177e4 LT |
159 | /* Number of dummy devices to be set up by this module. */ |
160 | module_param(numdummies, int, 0); | |
161 | MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices"); | |
162 | ||
206c9fb2 | 163 | static int __init dummy_init_one(void) |
1da177e4 LT |
164 | { |
165 | struct net_device *dev_dummy; | |
166 | int err; | |
167 | ||
2d85cba2 | 168 | dev_dummy = alloc_netdev(0, "dummy%d", dummy_setup); |
1da177e4 LT |
169 | if (!dev_dummy) |
170 | return -ENOMEM; | |
171 | ||
5d5cb173 PM |
172 | dev_dummy->rtnl_link_ops = &dummy_link_ops; |
173 | err = register_netdevice(dev_dummy); | |
174 | if (err < 0) | |
175 | goto err; | |
5d5cb173 | 176 | return 0; |
206c9fb2 | 177 | |
5d5cb173 PM |
178 | err: |
179 | free_netdev(dev_dummy); | |
180 | return err; | |
6aa20a22 | 181 | } |
1da177e4 LT |
182 | |
183 | static int __init dummy_init_module(void) | |
6aa20a22 | 184 | { |
1da177e4 | 185 | int i, err = 0; |
206c9fb2 | 186 | |
5d5cb173 PM |
187 | rtnl_lock(); |
188 | err = __rtnl_link_register(&dummy_link_ops); | |
189 | ||
1da177e4 | 190 | for (i = 0; i < numdummies && !err; i++) |
206c9fb2 | 191 | err = dummy_init_one(); |
2d85cba2 | 192 | if (err < 0) |
5d5cb173 | 193 | __rtnl_link_unregister(&dummy_link_ops); |
5d5cb173 PM |
194 | rtnl_unlock(); |
195 | ||
1da177e4 | 196 | return err; |
6aa20a22 | 197 | } |
1da177e4 LT |
198 | |
199 | static void __exit dummy_cleanup_module(void) | |
200 | { | |
2d85cba2 | 201 | rtnl_link_unregister(&dummy_link_ops); |
1da177e4 LT |
202 | } |
203 | ||
204 | module_init(dummy_init_module); | |
205 | module_exit(dummy_cleanup_module); | |
206 | MODULE_LICENSE("GPL"); | |
5d5cb173 | 207 | MODULE_ALIAS_RTNL_LINK("dummy"); |