/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* Pseudo-driver for the loopback interface.
*
* Version: @(#)loopback.c 1.0.4b 08/16/93
*
* Authors: Ross Biro
* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
* Donald Becker, <becker@scyld.com>
*
* Alan Cox : Fixed oddments for NET3.014
* Alan Cox : Rejig for NET3.029 snap #3
* Alan Cox : Fixed NET3.029 bugs and sped up
* Larry McVoy : Tiny tweak to double performance
* Alan Cox : Backed out LMV's tweak - the linux mm
* can't take it...
* Michael Griffith: Don't bother computing the checksums
* on packets received on the loopback
* interface.
* Alexey Kuznetsov: Potential hang under some extreme
* cases removed.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/socket.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/in.h>
#include <linux/init.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/ethtool.h>
#include <net/sock.h>
#include <net/checksum.h>
#include <linux/if_ether.h> /* For the statistics structure. */
#include <linux/if_arp.h> /* For ARPHRD_ETHER */
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/percpu.h>
#include <net/net_namespace.h>
struct pcpu_lstats {
unsigned long packets;
unsigned long bytes;
unsigned long drops;
};
/*
* The higher levels take care of making this non-reentrant (it's
* called with bh's disabled).
*/
static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct pcpu_lstats *pcpu_lstats, *lb_stats;
int len;
skb_orphan(skb);
skb->protocol = eth_type_trans(skb, dev);
/* it's OK to use per_cpu_ptr() because BHs are off */
pcpu_lstats = dev->ml_priv;
lb_stats = per_cpu_ptr(pcpu_lstats, smp_processor_id());
len = skb->len;
if (likely(netif_rx(skb) == NET_RX_SUCCESS)) {
lb_stats->bytes += len;
lb_stats->packets++;
} else
lb_stats->drops++;
return NETDEV_TX_OK;
}
static struct net_device_stats *loopback_get_stats(struct net_device *dev)
{
const struct pcpu_lstats *pcpu_lstats;
struct net_device_stats *stats = &dev->stats;
unsigned long bytes = 0;
unsigned long packets = 0;
unsigned long drops = 0;
int i;
pcpu_lstats = dev->ml_priv;
for_each_possible_cpu(i) {
const struct pcpu_lstats *lb_stats;
lb_stats = per_cpu_ptr(pcpu_lstats, i);
bytes += lb_stats->bytes;
packets += lb_stats->packets;
drops += lb_stats->drops;
}
stats->rx_packets = packets;
stats->tx_packets = packets;
stats->rx_dropped = drops;
stats->rx_errors = drops;
stats->rx_bytes = bytes;
stats->tx_bytes = bytes;
return stats;
}
static u32 always_on(struct net_device *dev)
{
return 1;
}
static const struct ethtool_ops loopback_ethtool_ops = {
.get_link = always_on,
.set_tso = ethtool_op_set_tso,
.get_tx_csum = always_on,
.get_sg = always_on,
.get_rx_csum = always_on,
};
static int loopback_dev_init(struct net_device *dev)
{
struct pcpu_lstats *lstats;
lstats = alloc_percpu(struct pcpu_lstats);
if (!lstats)
return -ENOMEM;
dev->ml_priv = lstats;
return 0;
}
static void loopback_dev_free(struct net_device *dev)
{
struct pcpu_lstats *lstats = dev->ml_priv;
free_percpu(lstats);
free_netdev(dev);
}
static const struct net_device_ops loopback_ops = {
.ndo_init = loopback_dev_init,
.ndo_start_xmit= loopback_xmit,
.ndo_get_stats = loopback_get_stats,
};
/*
* The loopback device is special. There is only one instance
* per network namespace.
*/
static void loopback_setup(struct net_device *dev)
{
dev->mtu = (16 * 1024) + 20 + 20 + 12;
dev->hard_header_len = ETH_HLEN; /* 14 */
dev->addr_len = ETH_ALEN; /* 6 */
dev->tx_queue_len = 0;
dev->type = ARPHRD_LOOPBACK; /* 0x0001*/
dev->flags = IFF_LOOPBACK;
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
dev->features = NETIF_F_SG | NETIF_F_FRAGLIST
| NETIF_F_TSO
| NETIF_F_NO_CSUM
| NETIF_F_HIGHDMA
| NETIF_F_LLTX
| NETIF_F_NETNS_LOCAL;
dev->ethtool_ops = &loopback_ethtool_ops;
dev->header_ops = ð_header_ops;
dev->netdev_ops = &loopback_ops;
dev->destructor = loopback_dev_free;
}
/* Setup and register the loopback device. */
static __net_init int loopback_net_init(struct net *net)
{
struct net_device *dev;
int err;
err = -ENOMEM;
dev = alloc_netdev(0, "lo", loopback_setup);
if (!dev)
goto out;
dev_net_set(dev, net);
err = register_netdev(dev);
if (err)
goto out_free_netdev;
net->loopback_dev = dev;
return 0;
out_free_netdev:
free_netdev(dev);
out:
if (net == &init_net)
panic("loopback: Failed to register netdevice: %d\n", err);
return err;
}
static __net_exit void loopback_net_exit(struct net *net)
{
struct net_device *dev = net->loopback_dev;
unregister_netdev(dev);
}
/* Registered in net/core/dev.c */
struct pernet_operations __net_initdata loopback_net_ops = {
.init = loopback_net_init,
.exit = loopback_net_exit,
};
