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 | /* fake multicast ability */ |
44 | static void set_multicast_list(struct net_device *dev) | |
45 | { | |
46 | } | |
47 | ||
6d81f41c ED |
48 | struct pcpu_dstats { |
49 | u64 tx_packets; | |
50 | u64 tx_bytes; | |
51 | struct u64_stats_sync syncp; | |
52 | }; | |
53 | ||
54 | static struct rtnl_link_stats64 *dummy_get_stats64(struct net_device *dev, | |
55 | struct rtnl_link_stats64 *stats) | |
56 | { | |
57 | int i; | |
58 | ||
59 | for_each_possible_cpu(i) { | |
60 | const struct pcpu_dstats *dstats; | |
61 | u64 tbytes, tpackets; | |
62 | unsigned int start; | |
63 | ||
64 | dstats = per_cpu_ptr(dev->dstats, i); | |
65 | do { | |
e3906486 | 66 | start = u64_stats_fetch_begin_bh(&dstats->syncp); |
6d81f41c ED |
67 | tbytes = dstats->tx_bytes; |
68 | tpackets = dstats->tx_packets; | |
e3906486 | 69 | } while (u64_stats_fetch_retry_bh(&dstats->syncp, start)); |
6d81f41c ED |
70 | stats->tx_bytes += tbytes; |
71 | stats->tx_packets += tpackets; | |
72 | } | |
73 | return stats; | |
74 | } | |
424efe9c SH |
75 | |
76 | static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev) | |
77 | { | |
6d81f41c ED |
78 | struct pcpu_dstats *dstats = this_cpu_ptr(dev->dstats); |
79 | ||
80 | u64_stats_update_begin(&dstats->syncp); | |
81 | dstats->tx_packets++; | |
82 | dstats->tx_bytes += skb->len; | |
83 | u64_stats_update_end(&dstats->syncp); | |
424efe9c SH |
84 | |
85 | dev_kfree_skb(skb); | |
86 | return NETDEV_TX_OK; | |
87 | } | |
88 | ||
6d81f41c ED |
89 | static int dummy_dev_init(struct net_device *dev) |
90 | { | |
91 | dev->dstats = alloc_percpu(struct pcpu_dstats); | |
92 | if (!dev->dstats) | |
93 | return -ENOMEM; | |
94 | ||
95 | return 0; | |
96 | } | |
97 | ||
890fdf2a | 98 | static void dummy_dev_uninit(struct net_device *dev) |
6d81f41c ED |
99 | { |
100 | free_percpu(dev->dstats); | |
6d81f41c ED |
101 | } |
102 | ||
210ab665 JP |
103 | static int dummy_change_carrier(struct net_device *dev, bool new_carrier) |
104 | { | |
105 | if (new_carrier) | |
106 | netif_carrier_on(dev); | |
107 | else | |
108 | netif_carrier_off(dev); | |
109 | return 0; | |
110 | } | |
111 | ||
aa18e9e8 | 112 | static const struct net_device_ops dummy_netdev_ops = { |
6d81f41c | 113 | .ndo_init = dummy_dev_init, |
890fdf2a | 114 | .ndo_uninit = dummy_dev_uninit, |
aa18e9e8 SH |
115 | .ndo_start_xmit = dummy_xmit, |
116 | .ndo_validate_addr = eth_validate_addr, | |
afc4b13d | 117 | .ndo_set_rx_mode = set_multicast_list, |
0d1632b4 | 118 | .ndo_set_mac_address = eth_mac_addr, |
6d81f41c | 119 | .ndo_get_stats64 = dummy_get_stats64, |
210ab665 | 120 | .ndo_change_carrier = dummy_change_carrier, |
aa18e9e8 SH |
121 | }; |
122 | ||
5d5cb173 | 123 | static void dummy_setup(struct net_device *dev) |
1da177e4 | 124 | { |
aa18e9e8 SH |
125 | ether_setup(dev); |
126 | ||
1da177e4 | 127 | /* Initialize the device structure. */ |
aa18e9e8 | 128 | dev->netdev_ops = &dummy_netdev_ops; |
890fdf2a | 129 | dev->destructor = free_netdev; |
1da177e4 LT |
130 | |
131 | /* Fill in device structure with ethernet-generic values. */ | |
1da177e4 | 132 | dev->tx_queue_len = 0; |
1da177e4 LT |
133 | dev->flags |= IFF_NOARP; |
134 | dev->flags &= ~IFF_MULTICAST; | |
0d1632b4 | 135 | dev->priv_flags |= IFF_LIVE_ADDR_CHANGE; |
6d81f41c | 136 | dev->features |= NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_TSO; |
34324dc2 | 137 | dev->features |= NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX; |
7ce5d222 | 138 | eth_hw_addr_random(dev); |
1da177e4 | 139 | } |
6d81f41c | 140 | |
0e06877c PM |
141 | static 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 | ||
5d5cb173 PM |
152 | static struct rtnl_link_ops dummy_link_ops __read_mostly = { |
153 | .kind = "dummy", | |
5d5cb173 | 154 | .setup = dummy_setup, |
0e06877c | 155 | .validate = dummy_validate, |
5d5cb173 PM |
156 | }; |
157 | ||
1da177e4 LT |
158 | /* Number of dummy devices to be set up by this module. */ |
159 | module_param(numdummies, int, 0); | |
160 | MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices"); | |
161 | ||
206c9fb2 | 162 | static int __init dummy_init_one(void) |
1da177e4 LT |
163 | { |
164 | struct net_device *dev_dummy; | |
165 | int err; | |
166 | ||
2d85cba2 | 167 | dev_dummy = alloc_netdev(0, "dummy%d", dummy_setup); |
1da177e4 LT |
168 | if (!dev_dummy) |
169 | return -ENOMEM; | |
170 | ||
5d5cb173 PM |
171 | dev_dummy->rtnl_link_ops = &dummy_link_ops; |
172 | err = register_netdevice(dev_dummy); | |
173 | if (err < 0) | |
174 | goto err; | |
5d5cb173 | 175 | return 0; |
206c9fb2 | 176 | |
5d5cb173 PM |
177 | err: |
178 | free_netdev(dev_dummy); | |
179 | return err; | |
6aa20a22 | 180 | } |
1da177e4 LT |
181 | |
182 | static int __init dummy_init_module(void) | |
6aa20a22 | 183 | { |
1da177e4 | 184 | int i, err = 0; |
206c9fb2 | 185 | |
5d5cb173 PM |
186 | rtnl_lock(); |
187 | err = __rtnl_link_register(&dummy_link_ops); | |
188 | ||
16b0dc29 | 189 | for (i = 0; i < numdummies && !err; i++) { |
206c9fb2 | 190 | err = dummy_init_one(); |
16b0dc29 ED |
191 | cond_resched(); |
192 | } | |
2d85cba2 | 193 | if (err < 0) |
5d5cb173 | 194 | __rtnl_link_unregister(&dummy_link_ops); |
5d5cb173 PM |
195 | rtnl_unlock(); |
196 | ||
1da177e4 | 197 | return err; |
6aa20a22 | 198 | } |
1da177e4 LT |
199 | |
200 | static void __exit dummy_cleanup_module(void) | |
201 | { | |
2d85cba2 | 202 | rtnl_link_unregister(&dummy_link_ops); |
1da177e4 LT |
203 | } |
204 | ||
205 | module_init(dummy_init_module); | |
206 | module_exit(dummy_cleanup_module); | |
207 | MODULE_LICENSE("GPL"); | |
5d5cb173 | 208 | MODULE_ALIAS_RTNL_LINK("dummy"); |