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