Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
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linux
1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Pseudo-driver for the loopback interface.
7 *
8 * Version: @(#)loopback.c 1.0.4b 08/16/93
9 *
10 * Authors: Ross Biro
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 * Donald Becker, <becker@scyld.com>
13 *
14 * Alan Cox : Fixed oddments for NET3.014
15 * Alan Cox : Rejig for NET3.029 snap #3
16 * Alan Cox : Fixed NET3.029 bugs and sped up
17 * Larry McVoy : Tiny tweak to double performance
18 * Alan Cox : Backed out LMV's tweak - the linux mm
19 * can't take it...
20 * Michael Griffith: Don't bother computing the checksums
21 * on packets received on the loopback
22 * interface.
23 * Alexey Kuznetsov: Potential hang under some extreme
24 * cases removed.
25 *
26 * This program is free software; you can redistribute it and/or
27 * modify it under the terms of the GNU General Public License
28 * as published by the Free Software Foundation; either version
29 * 2 of the License, or (at your option) any later version.
30 */
31#include <linux/kernel.h>
32#include <linux/jiffies.h>
33#include <linux/module.h>
34#include <linux/interrupt.h>
35#include <linux/fs.h>
36#include <linux/types.h>
37#include <linux/string.h>
38#include <linux/socket.h>
39#include <linux/errno.h>
40#include <linux/fcntl.h>
41#include <linux/in.h>
42#include <linux/init.h>
43
44#include <asm/system.h>
45#include <asm/uaccess.h>
46#include <asm/io.h>
47
48#include <linux/inet.h>
49#include <linux/netdevice.h>
50#include <linux/etherdevice.h>
51#include <linux/skbuff.h>
52#include <linux/ethtool.h>
53#include <net/sock.h>
54#include <net/checksum.h>
55#include <linux/if_ether.h> /* For the statistics structure. */
56#include <linux/if_arp.h> /* For ARPHRD_ETHER */
57#include <linux/ip.h>
58#include <linux/tcp.h>
59#include <linux/percpu.h>
60#include <net/net_namespace.h>
61
62struct pcpu_lstats {
63 unsigned long packets;
64 unsigned long bytes;
65};
66
67/*
68 * The higher levels take care of making this non-reentrant (it's
69 * called with bh's disabled).
70 */
71static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
72{
73 struct pcpu_lstats *pcpu_lstats, *lb_stats;
74
75 skb_orphan(skb);
76
77 skb->protocol = eth_type_trans(skb,dev);
78
79 dev->last_rx = jiffies;
80
81 /* it's OK to use per_cpu_ptr() because BHs are off */
82 pcpu_lstats = dev->ml_priv;
83 lb_stats = per_cpu_ptr(pcpu_lstats, smp_processor_id());
84 lb_stats->bytes += skb->len;
85 lb_stats->packets++;
86
87 netif_rx(skb);
88
89 return 0;
90}
91
92static struct net_device_stats *get_stats(struct net_device *dev)
93{
94 const struct pcpu_lstats *pcpu_lstats;
95 struct net_device_stats *stats = &dev->stats;
96 unsigned long bytes = 0;
97 unsigned long packets = 0;
98 int i;
99
100 pcpu_lstats = dev->ml_priv;
101 for_each_possible_cpu(i) {
102 const struct pcpu_lstats *lb_stats;
103
104 lb_stats = per_cpu_ptr(pcpu_lstats, i);
105 bytes += lb_stats->bytes;
106 packets += lb_stats->packets;
107 }
108 stats->rx_packets = packets;
109 stats->tx_packets = packets;
110 stats->rx_bytes = bytes;
111 stats->tx_bytes = bytes;
112 return stats;
113}
114
115static u32 always_on(struct net_device *dev)
116{
117 return 1;
118}
119
120static const struct ethtool_ops loopback_ethtool_ops = {
121 .get_link = always_on,
122 .set_tso = ethtool_op_set_tso,
123 .get_tx_csum = always_on,
124 .get_sg = always_on,
125 .get_rx_csum = always_on,
126};
127
128static int loopback_dev_init(struct net_device *dev)
129{
130 struct pcpu_lstats *lstats;
131
132 lstats = alloc_percpu(struct pcpu_lstats);
133 if (!lstats)
134 return -ENOMEM;
135
136 dev->ml_priv = lstats;
137 return 0;
138}
139
140static void loopback_dev_free(struct net_device *dev)
141{
142 struct pcpu_lstats *lstats = dev->ml_priv;
143
144 free_percpu(lstats);
145 free_netdev(dev);
146}
147
148/*
149 * The loopback device is special. There is only one instance
150 * per network namespace.
151 */
152static void loopback_setup(struct net_device *dev)
153{
154 dev->get_stats = &get_stats;
155 dev->mtu = (16 * 1024) + 20 + 20 + 12;
156 dev->hard_start_xmit = loopback_xmit;
157 dev->hard_header_len = ETH_HLEN; /* 14 */
158 dev->addr_len = ETH_ALEN; /* 6 */
159 dev->tx_queue_len = 0;
160 dev->type = ARPHRD_LOOPBACK; /* 0x0001*/
161 dev->flags = IFF_LOOPBACK;
162 dev->features = NETIF_F_SG | NETIF_F_FRAGLIST
163 | NETIF_F_TSO
164 | NETIF_F_NO_CSUM
165 | NETIF_F_HIGHDMA
166 | NETIF_F_LLTX
167 | NETIF_F_NETNS_LOCAL;
168 dev->ethtool_ops = &loopback_ethtool_ops;
169 dev->header_ops = ð_header_ops;
170 dev->init = loopback_dev_init;
171 dev->destructor = loopback_dev_free;
172}
173
174/* Setup and register the loopback device. */
175static __net_init int loopback_net_init(struct net *net)
176{
177 struct net_device *dev;
178 int err;
179
180 err = -ENOMEM;
181 dev = alloc_netdev(0, "lo", loopback_setup);
182 if (!dev)
183 goto out;
184
185 dev_net_set(dev, net);
186 err = register_netdev(dev);
187 if (err)
188 goto out_free_netdev;
189
190 net->loopback_dev = dev;
191 return 0;
192
193
194out_free_netdev:
195 free_netdev(dev);
196out:
197 if (net == &init_net)
198 panic("loopback: Failed to register netdevice: %d\n", err);
199 return err;
200}
201
202static __net_exit void loopback_net_exit(struct net *net)
203{
204 struct net_device *dev = net->loopback_dev;
205
206 unregister_netdev(dev);
207}
208
209static struct pernet_operations __net_initdata loopback_net_ops = {
210 .init = loopback_net_init,
211 .exit = loopback_net_exit,
212};
213
214static int __init loopback_init(void)
215{
216 return register_pernet_device(&loopback_net_ops);
217}
218
219/* Loopback is special. It should be initialized before any other network
220 * device and network subsystem.
221 */
222fs_initcall(loopback_init);