238 lines
6.3 KiB
C
238 lines
6.3 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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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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static DEFINE_PER_CPU(struct pcpu_lstats, pcpu_lstats);
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#define LOOPBACK_OVERHEAD (128 + MAX_HEADER + 16 + 16)
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/* KISS: just allocate small chunks and copy bits.
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*
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* So, in fact, this is documentation, explaining what we expect
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* of largesending device modulo TCP checksum, which is ignored for loopback.
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*/
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#ifdef LOOPBACK_TSO
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static void emulate_large_send_offload(struct sk_buff *skb)
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{
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struct iphdr *iph = ip_hdr(skb);
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struct tcphdr *th = (struct tcphdr *)(skb_network_header(skb) +
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(iph->ihl * 4));
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unsigned int doffset = (iph->ihl + th->doff) * 4;
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unsigned int mtu = skb_shinfo(skb)->gso_size + doffset;
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unsigned int offset = 0;
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u32 seq = ntohl(th->seq);
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u16 id = ntohs(iph->id);
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while (offset + doffset < skb->len) {
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unsigned int frag_size = min(mtu, skb->len - offset) - doffset;
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struct sk_buff *nskb = alloc_skb(mtu + 32, GFP_ATOMIC);
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if (!nskb)
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break;
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skb_reserve(nskb, 32);
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skb_set_mac_header(nskb, -ETH_HLEN);
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skb_reset_network_header(nskb);
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iph = ip_hdr(nskb);
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skb_copy_to_linear_data(nskb, skb_network_header(skb),
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doffset);
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if (skb_copy_bits(skb,
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doffset + offset,
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nskb->data + doffset,
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frag_size))
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BUG();
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skb_put(nskb, doffset + frag_size);
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nskb->ip_summed = CHECKSUM_UNNECESSARY;
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nskb->dev = skb->dev;
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nskb->priority = skb->priority;
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nskb->protocol = skb->protocol;
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nskb->dst = dst_clone(skb->dst);
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memcpy(nskb->cb, skb->cb, sizeof(skb->cb));
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nskb->pkt_type = skb->pkt_type;
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th = (struct tcphdr *)(skb_network_header(nskb) + iph->ihl * 4);
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iph->tot_len = htons(frag_size + doffset);
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iph->id = htons(id);
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iph->check = 0;
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iph->check = ip_fast_csum((unsigned char *) iph, iph->ihl);
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th->seq = htonl(seq);
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if (offset + doffset + frag_size < skb->len)
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th->fin = th->psh = 0;
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netif_rx(nskb);
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offset += frag_size;
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seq += frag_size;
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id++;
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}
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dev_kfree_skb(skb);
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}
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#endif /* LOOPBACK_TSO */
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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 *lb_stats;
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skb_orphan(skb);
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skb->protocol = eth_type_trans(skb,dev);
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#ifndef LOOPBACK_MUST_CHECKSUM
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skb->ip_summed = CHECKSUM_UNNECESSARY;
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#endif
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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 __get_cpu_var() because BHs are off */
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lb_stats = &__get_cpu_var(pcpu_lstats);
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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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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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for_each_possible_cpu(i) {
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const struct pcpu_lstats *lb_stats;
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lb_stats = &per_cpu(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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.get_tso = ethtool_op_get_tso,
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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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/*
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* The loopback device is special. There is only one instance and
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* it is statically allocated. Don't do this for other devices.
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*/
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struct net_device loopback_dev = {
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.name = "lo",
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.get_stats = &get_stats,
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.mtu = (16 * 1024) + 20 + 20 + 12,
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.hard_start_xmit = loopback_xmit,
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.hard_header = eth_header,
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.hard_header_cache = eth_header_cache,
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.header_cache_update = eth_header_cache_update,
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.hard_header_len = ETH_HLEN, /* 14 */
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.addr_len = ETH_ALEN, /* 6 */
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.tx_queue_len = 0,
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.type = ARPHRD_LOOPBACK, /* 0x0001*/
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.rebuild_header = eth_rebuild_header,
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.flags = IFF_LOOPBACK,
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.features = NETIF_F_SG | NETIF_F_FRAGLIST
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#ifdef LOOPBACK_TSO
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| NETIF_F_TSO
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#endif
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| NETIF_F_NO_CSUM | NETIF_F_HIGHDMA
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| NETIF_F_LLTX,
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.ethtool_ops = &loopback_ethtool_ops,
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};
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/* Setup and register the loopback device. */
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static int __init loopback_init(void)
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{
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return register_netdev(&loopback_dev);
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};
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module_init(loopback_init);
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EXPORT_SYMBOL(loopback_dev);
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