projects/linux·blob v3.3 · refs

216 lines · 5.4 KiB

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, <[email protected]>
12 * Donald Becker, <[email protected]>
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#include <linux/u64_stats_sync.h>
62
63struct pcpu_lstats {
64 u64 packets;
65 u64 bytes;
66 struct u64_stats_sync syncp;
67};
68
69/*
70 * The higher levels take care of making this non-reentrant (it's
71 * called with bh's disabled).
72 */
73static netdev_tx_t loopback_xmit(struct sk_buff *skb,
74 struct net_device *dev)
75{
76 struct pcpu_lstats *lb_stats;
77 int len;
78
79 skb_orphan(skb);
80
81 skb->protocol = eth_type_trans(skb, dev);
82
83 /* it's OK to use per_cpu_ptr() because BHs are off */
84 lb_stats = this_cpu_ptr(dev->lstats);
85
86 len = skb->len;
87 if (likely(netif_rx(skb) == NET_RX_SUCCESS)) {
88 u64_stats_update_begin(&lb_stats->syncp);
89 lb_stats->bytes += len;
90 lb_stats->packets++;
91 u64_stats_update_end(&lb_stats->syncp);
92 }
93
94 return NETDEV_TX_OK;
95}
96
97static struct rtnl_link_stats64 *loopback_get_stats64(struct net_device *dev,
98 struct rtnl_link_stats64 *stats)
99{
100 u64 bytes = 0;
101 u64 packets = 0;
102 int i;
103
104 for_each_possible_cpu(i) {
105 const struct pcpu_lstats *lb_stats;
106 u64 tbytes, tpackets;
107 unsigned int start;
108
109 lb_stats = per_cpu_ptr(dev->lstats, i);
110 do {
111 start = u64_stats_fetch_begin(&lb_stats->syncp);
112 tbytes = lb_stats->bytes;
113 tpackets = lb_stats->packets;
114 } while (u64_stats_fetch_retry(&lb_stats->syncp, start));
115 bytes += tbytes;
116 packets += tpackets;
117 }
118 stats->rx_packets = packets;
119 stats->tx_packets = packets;
120 stats->rx_bytes = bytes;
121 stats->tx_bytes = bytes;
122 return stats;
123}
124
125static u32 always_on(struct net_device *dev)
126{
127 return 1;
128}
129
130static const struct ethtool_ops loopback_ethtool_ops = {
131 .get_link = always_on,
132};
133
134static int loopback_dev_init(struct net_device *dev)
135{
136 dev->lstats = alloc_percpu(struct pcpu_lstats);
137 if (!dev->lstats)
138 return -ENOMEM;
139
140 return 0;
141}
142
143static void loopback_dev_free(struct net_device *dev)
144{
145 free_percpu(dev->lstats);
146 free_netdev(dev);
147}
148
149static const struct net_device_ops loopback_ops = {
150 .ndo_init = loopback_dev_init,
151 .ndo_start_xmit= loopback_xmit,
152 .ndo_get_stats64 = loopback_get_stats64,
153};
154
155/*
156 * The loopback device is special. There is only one instance
157 * per network namespace.
158 */
159static void loopback_setup(struct net_device *dev)
160{
161 dev->mtu = (16 * 1024) + 20 + 20 + 12;
162 dev->hard_header_len = ETH_HLEN; /* 14 */
163 dev->addr_len = ETH_ALEN; /* 6 */
164 dev->tx_queue_len = 0;
165 dev->type = ARPHRD_LOOPBACK; /* 0x0001*/
166 dev->flags = IFF_LOOPBACK;
167 dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
168 dev->hw_features = NETIF_F_ALL_TSO | NETIF_F_UFO;
169 dev->features = NETIF_F_SG | NETIF_F_FRAGLIST
170 | NETIF_F_ALL_TSO
171 | NETIF_F_UFO
172 | NETIF_F_HW_CSUM
173 | NETIF_F_RXCSUM
174 | NETIF_F_HIGHDMA
175 | NETIF_F_LLTX
176 | NETIF_F_NETNS_LOCAL
177 | NETIF_F_VLAN_CHALLENGED
178 | NETIF_F_LOOPBACK;
179 dev->ethtool_ops = &loopback_ethtool_ops;
180 dev->header_ops = &eth_header_ops;
181 dev->netdev_ops = &loopback_ops;
182 dev->destructor = loopback_dev_free;
183}
184
185/* Setup and register the loopback device. */
186static __net_init int loopback_net_init(struct net *net)
187{
188 struct net_device *dev;
189 int err;
190
191 err = -ENOMEM;
192 dev = alloc_netdev(0, "lo", loopback_setup);
193 if (!dev)
194 goto out;
195
196 dev_net_set(dev, net);
197 err = register_netdev(dev);
198 if (err)
199 goto out_free_netdev;
200
201 net->loopback_dev = dev;
202 return 0;
203
204
205out_free_netdev:
206 free_netdev(dev);
207out:
208 if (net_eq(net, &init_net))
209 panic("loopback: Failed to register netdevice: %d\n", err);
210 return err;
211}
212
213/* Registered in net/core/dev.c */
214struct pernet_operations __net_initdata loopback_net_ops = {
215 .init = loopback_net_init,
216};