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https://github.com/edk2-porting/linux-next.git
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0287587884
Testing xmit_more support with netperf and connected UDP sockets, I found strange dst refcount false sharing. Current handling of IFF_XMIT_DST_RELEASE is not optimal. Dropping dst in validate_xmit_skb() is certainly too late in case packet was queued by cpu X but dequeued by cpu Y The logical point to take care of drop/force is in __dev_queue_xmit() before even taking qdisc lock. As Julian Anastasov pointed out, need for skb_dst() might come from some packet schedulers or classifiers. This patch adds new helper to cleanly express needs of various drivers or qdiscs/classifiers. Drivers that need skb_dst() in their ndo_start_xmit() should call following helper in their setup instead of the prior : dev->priv_flags &= ~IFF_XMIT_DST_RELEASE; -> netif_keep_dst(dev); Instead of using a single bit, we use two bits, one being eventually rebuilt in bonding/team drivers. The other one, is permanent and blocks IFF_XMIT_DST_RELEASE being rebuilt in bonding/team. Eventually, we could add something smarter later. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Julian Anastasov <ja@ssi.bg> Signed-off-by: David S. Miller <davem@davemloft.net>
224 lines
5.6 KiB
C
224 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 <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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#include <linux/u64_stats_sync.h>
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struct pcpu_lstats {
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u64 packets;
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u64 bytes;
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struct u64_stats_sync syncp;
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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 netdev_tx_t loopback_xmit(struct sk_buff *skb,
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struct net_device *dev)
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{
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struct pcpu_lstats *lb_stats;
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int len;
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skb_orphan(skb);
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/* Before queueing this packet to netif_rx(),
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* make sure dst is refcounted.
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*/
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skb_dst_force(skb);
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skb->protocol = eth_type_trans(skb, dev);
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/* it's OK to use per_cpu_ptr() because BHs are off */
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lb_stats = this_cpu_ptr(dev->lstats);
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len = skb->len;
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if (likely(netif_rx(skb) == NET_RX_SUCCESS)) {
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u64_stats_update_begin(&lb_stats->syncp);
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lb_stats->bytes += len;
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lb_stats->packets++;
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u64_stats_update_end(&lb_stats->syncp);
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}
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return NETDEV_TX_OK;
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}
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static struct rtnl_link_stats64 *loopback_get_stats64(struct net_device *dev,
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struct rtnl_link_stats64 *stats)
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{
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u64 bytes = 0;
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u64 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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u64 tbytes, tpackets;
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unsigned int start;
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lb_stats = per_cpu_ptr(dev->lstats, i);
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do {
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start = u64_stats_fetch_begin_irq(&lb_stats->syncp);
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tbytes = lb_stats->bytes;
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tpackets = lb_stats->packets;
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} while (u64_stats_fetch_retry_irq(&lb_stats->syncp, start));
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bytes += tbytes;
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packets += tpackets;
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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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};
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static int loopback_dev_init(struct net_device *dev)
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{
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dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
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if (!dev->lstats)
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return -ENOMEM;
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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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dev_net(dev)->loopback_dev = NULL;
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free_percpu(dev->lstats);
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free_netdev(dev);
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}
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static const struct net_device_ops loopback_ops = {
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.ndo_init = loopback_dev_init,
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.ndo_start_xmit= loopback_xmit,
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.ndo_get_stats64 = loopback_get_stats64,
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.ndo_set_mac_address = eth_mac_addr,
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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->mtu = 64 * 1024;
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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->priv_flags |= IFF_LIVE_ADDR_CHANGE;
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netif_keep_dst(dev);
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dev->hw_features = NETIF_F_ALL_TSO | NETIF_F_UFO;
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dev->features = NETIF_F_SG | NETIF_F_FRAGLIST
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| NETIF_F_ALL_TSO
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| NETIF_F_UFO
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| NETIF_F_HW_CSUM
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| NETIF_F_RXCSUM
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| NETIF_F_SCTP_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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| NETIF_F_VLAN_CHALLENGED
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| NETIF_F_LOOPBACK;
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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->netdev_ops = &loopback_ops;
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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", NET_NAME_UNKNOWN, 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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BUG_ON(dev->ifindex != LOOPBACK_IFINDEX);
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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_eq(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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/* Registered in net/core/dev.c */
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struct pernet_operations __net_initdata loopback_net_ops = {
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.init = loopback_net_init,
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};
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