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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>
56#include <linux/if_arp.h>
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
71
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
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 .set_tso = ethtool_op_set_tso,
133 .get_tx_csum = always_on,
134 .get_sg = always_on,
135 .get_rx_csum = always_on,
136};
137
138static int loopback_dev_init(struct net_device *dev)
139{
140 dev->lstats = alloc_percpu(struct pcpu_lstats);
141 if (!dev->lstats)
142 return -ENOMEM;
143
144 return 0;
145}
146
147static void loopback_dev_free(struct net_device *dev)
148{
149 free_percpu(dev->lstats);
150 free_netdev(dev);
151}
152
153static const struct net_device_ops loopback_ops = {
154 .ndo_init = loopback_dev_init,
155 .ndo_start_xmit= loopback_xmit,
156 .ndo_get_stats64 = loopback_get_stats64,
157};
158
159
160
161
162
163static void loopback_setup(struct net_device *dev)
164{
165 dev->mtu = (16 * 1024) + 20 + 20 + 12;
166 dev->hard_header_len = ETH_HLEN;
167 dev->addr_len = ETH_ALEN;
168 dev->tx_queue_len = 0;
169 dev->type = ARPHRD_LOOPBACK;
170 dev->flags = IFF_LOOPBACK;
171 dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
172 dev->features = NETIF_F_SG | NETIF_F_FRAGLIST
173 | NETIF_F_TSO
174 | NETIF_F_NO_CSUM
175 | NETIF_F_HIGHDMA
176 | NETIF_F_LLTX
177 | NETIF_F_NETNS_LOCAL;
178 dev->ethtool_ops = &loopback_ethtool_ops;
179 dev->header_ops = ð_header_ops;
180 dev->netdev_ops = &loopback_ops;
181 dev->destructor = loopback_dev_free;
182}
183
184
185static __net_init int loopback_net_init(struct net *net)
186{
187 struct net_device *dev;
188 int err;
189
190 err = -ENOMEM;
191 dev = alloc_netdev(0, "lo", loopback_setup);
192 if (!dev)
193 goto out;
194
195 dev_net_set(dev, net);
196 err = register_netdev(dev);
197 if (err)
198 goto out_free_netdev;
199
200 net->loopback_dev = dev;
201 return 0;
202
203
204out_free_netdev:
205 free_netdev(dev);
206out:
207 if (net_eq(net, &init_net))
208 panic("loopback: Failed to register netdevice: %d\n", err);
209 return err;
210}
211
212
213struct pernet_operations __net_initdata loopback_net_ops = {
214 .init = loopback_net_init,
215};
216