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![Herbert Xu](/assets/img/avatar_default.png)
Now that the network stack can handle inbound packets with partial checksums, we should no longer clobber the ip_summed field in the loopback driver. This is because CHECKSUM_UNNECESSARY implies that the checksum field is actually valid which is not true for loopback packets since it's only partial (and thus complemented). This allows packets from lo to then be SNATed to an external source while still preserving the checksum's validity. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
231 lines
5.6 KiB
C
231 lines
5.6 KiB
C
/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* Pseudo-driver for the loopback interface.
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*
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* Version: @(#)loopback.c 1.0.4b 08/16/93
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*
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* Authors: Ross Biro
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* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
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* Donald Becker, <becker@scyld.com>
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*
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* Alan Cox : Fixed oddments for NET3.014
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* Alan Cox : Rejig for NET3.029 snap #3
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* Alan Cox : Fixed NET3.029 bugs and sped up
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* Larry McVoy : Tiny tweak to double performance
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* Alan Cox : Backed out LMV's tweak - the linux mm
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* can't take it...
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* Michael Griffith: Don't bother computing the checksums
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* on packets received on the loopback
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* interface.
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* Alexey Kuznetsov: Potential hang under some extreme
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* cases removed.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/jiffies.h>
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#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/fs.h>
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#include <linux/types.h>
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#include <linux/string.h>
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#include <linux/socket.h>
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#include <linux/errno.h>
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#include <linux/fcntl.h>
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#include <linux/in.h>
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#include <linux/init.h>
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#include <asm/system.h>
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#include <asm/uaccess.h>
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#include <asm/io.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/etherdevice.h>
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#include <linux/skbuff.h>
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#include <linux/ethtool.h>
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#include <net/sock.h>
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#include <net/checksum.h>
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#include <linux/if_ether.h> /* For the statistics structure. */
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#include <linux/if_arp.h> /* For ARPHRD_ETHER */
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#include <linux/ip.h>
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#include <linux/tcp.h>
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#include <linux/percpu.h>
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#include <net/net_namespace.h>
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struct pcpu_lstats {
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unsigned long packets;
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unsigned long bytes;
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};
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/*
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* The higher levels take care of making this non-reentrant (it's
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* called with bh's disabled).
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*/
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static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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struct pcpu_lstats *pcpu_lstats, *lb_stats;
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skb_orphan(skb);
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skb->protocol = eth_type_trans(skb,dev);
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#ifdef LOOPBACK_TSO
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if (skb_is_gso(skb)) {
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BUG_ON(skb->protocol != htons(ETH_P_IP));
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BUG_ON(ip_hdr(skb)->protocol != IPPROTO_TCP);
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emulate_large_send_offload(skb);
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return 0;
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}
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#endif
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dev->last_rx = jiffies;
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/* it's OK to use per_cpu_ptr() because BHs are off */
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pcpu_lstats = dev->ml_priv;
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lb_stats = per_cpu_ptr(pcpu_lstats, smp_processor_id());
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lb_stats->bytes += skb->len;
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lb_stats->packets++;
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netif_rx(skb);
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return 0;
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}
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static struct net_device_stats *get_stats(struct net_device *dev)
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{
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const struct pcpu_lstats *pcpu_lstats;
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struct net_device_stats *stats = &dev->stats;
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unsigned long bytes = 0;
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unsigned long packets = 0;
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int i;
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pcpu_lstats = dev->ml_priv;
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for_each_possible_cpu(i) {
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const struct pcpu_lstats *lb_stats;
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lb_stats = per_cpu_ptr(pcpu_lstats, i);
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bytes += lb_stats->bytes;
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packets += lb_stats->packets;
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}
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stats->rx_packets = packets;
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stats->tx_packets = packets;
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stats->rx_bytes = bytes;
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stats->tx_bytes = bytes;
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return stats;
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}
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static u32 always_on(struct net_device *dev)
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{
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return 1;
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}
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static const struct ethtool_ops loopback_ethtool_ops = {
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.get_link = always_on,
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.set_tso = ethtool_op_set_tso,
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.get_tx_csum = always_on,
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.get_sg = always_on,
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.get_rx_csum = always_on,
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};
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static int loopback_dev_init(struct net_device *dev)
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{
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struct pcpu_lstats *lstats;
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lstats = alloc_percpu(struct pcpu_lstats);
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if (!lstats)
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return -ENOMEM;
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dev->ml_priv = lstats;
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return 0;
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}
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static void loopback_dev_free(struct net_device *dev)
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{
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struct pcpu_lstats *lstats = dev->ml_priv;
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free_percpu(lstats);
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free_netdev(dev);
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}
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/*
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* The loopback device is special. There is only one instance
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* per network namespace.
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*/
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static void loopback_setup(struct net_device *dev)
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{
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dev->get_stats = &get_stats;
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dev->mtu = (16 * 1024) + 20 + 20 + 12;
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dev->hard_start_xmit = loopback_xmit;
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dev->hard_header_len = ETH_HLEN; /* 14 */
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dev->addr_len = ETH_ALEN; /* 6 */
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dev->tx_queue_len = 0;
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dev->type = ARPHRD_LOOPBACK; /* 0x0001*/
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dev->flags = IFF_LOOPBACK;
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dev->features = NETIF_F_SG | NETIF_F_FRAGLIST
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| NETIF_F_TSO
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| NETIF_F_NO_CSUM
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| NETIF_F_HIGHDMA
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| NETIF_F_LLTX
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| NETIF_F_NETNS_LOCAL;
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dev->ethtool_ops = &loopback_ethtool_ops;
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dev->header_ops = ð_header_ops;
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dev->init = loopback_dev_init;
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dev->destructor = loopback_dev_free;
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}
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/* Setup and register the loopback device. */
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static __net_init int loopback_net_init(struct net *net)
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{
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struct net_device *dev;
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int err;
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err = -ENOMEM;
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dev = alloc_netdev(0, "lo", loopback_setup);
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if (!dev)
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goto out;
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dev_net_set(dev, net);
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err = register_netdev(dev);
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if (err)
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goto out_free_netdev;
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net->loopback_dev = dev;
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return 0;
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out_free_netdev:
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free_netdev(dev);
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out:
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if (net == &init_net)
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panic("loopback: Failed to register netdevice: %d\n", err);
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return err;
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}
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static __net_exit void loopback_net_exit(struct net *net)
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{
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struct net_device *dev = net->loopback_dev;
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unregister_netdev(dev);
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}
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static struct pernet_operations __net_initdata loopback_net_ops = {
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.init = loopback_net_init,
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.exit = loopback_net_exit,
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};
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static int __init loopback_init(void)
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{
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return register_pernet_device(&loopback_net_ops);
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}
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/* Loopback is special. It should be initialized before any other network
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* device and network subsystem.
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*/
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fs_initcall(loopback_init);
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