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 unsigned long drops;
66};
67
68/*
69 * The higher levels take care of making this non-reentrant (it's
70 * called with bh's disabled).
71 */
72static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
73{
74 struct pcpu_lstats *pcpu_lstats, *lb_stats;
75 int len;
76
77 skb_orphan(skb);
78
79 skb->protocol = eth_type_trans(skb, dev);
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
85 len = skb->len;
86 if (likely(netif_rx(skb) == NET_RX_SUCCESS)) {
87 lb_stats->bytes += len;
88 lb_stats->packets++;
89 } else
90 lb_stats->drops++;
91
92 return 0;
93}
94
95static struct net_device_stats *loopback_get_stats(struct net_device *dev)
96{
97 const struct pcpu_lstats *pcpu_lstats;
98 struct net_device_stats *stats = &dev->stats;
99 unsigned long bytes = 0;
100 unsigned long packets = 0;
101 unsigned long drops = 0;
102 int i;
103
104 pcpu_lstats = dev->ml_priv;
105 for_each_possible_cpu(i) {
106 const struct pcpu_lstats *lb_stats;
107
108 lb_stats = per_cpu_ptr(pcpu_lstats, i);
109 bytes += lb_stats->bytes;
110 packets += lb_stats->packets;
111 drops += lb_stats->drops;
112 }
113 stats->rx_packets = packets;
114 stats->tx_packets = packets;
115 stats->rx_dropped = drops;
116 stats->rx_errors = drops;
117 stats->rx_bytes = bytes;
118 stats->tx_bytes = bytes;
119 return stats;
120}
121
122static u32 always_on(struct net_device *dev)
123{
124 return 1;
125}
126
127static const struct ethtool_ops loopback_ethtool_ops = {
128 .get_link = always_on,
129 .set_tso = ethtool_op_set_tso,
130 .get_tx_csum = always_on,
131 .get_sg = always_on,
132 .get_rx_csum = always_on,
133};
134
135static int loopback_dev_init(struct net_device *dev)
136{
137 struct pcpu_lstats *lstats;
138
139 lstats = alloc_percpu(struct pcpu_lstats);
140 if (!lstats)
141 return -ENOMEM;
142
143 dev->ml_priv = lstats;
144 return 0;
145}
146
147static void loopback_dev_free(struct net_device *dev)
148{
149 struct pcpu_lstats *lstats = dev->ml_priv;
150
151 free_percpu(lstats);
152 free_netdev(dev);
153}
154
155static const struct net_device_ops loopback_ops = {
156 .ndo_init = loopback_dev_init,
157 .ndo_start_xmit= loopback_xmit,
158 .ndo_get_stats = loopback_get_stats,
159};
160
161/*
162 * The loopback device is special. There is only one instance
163 * per network namespace.
164 */
165static void loopback_setup(struct net_device *dev)
166{
167 dev->mtu = (16 * 1024) + 20 + 20 + 12;
168 dev->hard_header_len = ETH_HLEN; /* 14 */
169 dev->addr_len = ETH_ALEN; /* 6 */
170 dev->tx_queue_len = 0;
171 dev->type = ARPHRD_LOOPBACK; /* 0x0001*/
172 dev->flags = IFF_LOOPBACK;
173 dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
174 dev->features = NETIF_F_SG | NETIF_F_FRAGLIST
175 | NETIF_F_TSO
176 | NETIF_F_NO_CSUM
177 | NETIF_F_HIGHDMA
178 | NETIF_F_LLTX
179 | NETIF_F_NETNS_LOCAL;
180 dev->ethtool_ops = &loopback_ethtool_ops;
181 dev->header_ops = ð_header_ops;
182 dev->netdev_ops = &loopback_ops;
183 dev->destructor = loopback_dev_free;
184}
185
186/* Setup and register the loopback device. */
187static __net_init int loopback_net_init(struct net *net)
188{
189 struct net_device *dev;
190 int err;
191
192 err = -ENOMEM;
193 dev = alloc_netdev(0, "lo", loopback_setup);
194 if (!dev)
195 goto out;
196
197 dev_net_set(dev, net);
198 err = register_netdev(dev);
199 if (err)
200 goto out_free_netdev;
201
202 net->loopback_dev = dev;
203 return 0;
204
205
206out_free_netdev:
207 free_netdev(dev);
208out:
209 if (net == &init_net)
210 panic("loopback: Failed to register netdevice: %d\n", err);
211 return err;
212}
213
214static __net_exit void loopback_net_exit(struct net *net)
215{
216 struct net_device *dev = net->loopback_dev;
217
218 unregister_netdev(dev);
219}
220
221/* Registered in net/core/dev.c */
222struct pernet_operations __net_initdata loopback_net_ops = {
223 .init = loopback_net_init,
224 .exit = loopback_net_exit,
225};