loopback.c 5.4 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5 6 7 8 9
/*
 * 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
 *
10
 * Authors:	Ross Biro
L
Linus Torvalds 已提交
11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59
 *		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>
60
#include <net/net_namespace.h>
61
#include <linux/u64_stats_sync.h>
L
Linus Torvalds 已提交
62

63
struct pcpu_lstats {
64 65 66
	u64			packets;
	u64			bytes;
	struct u64_stats_sync	syncp;
67
};
L
Linus Torvalds 已提交
68 69 70 71 72

/*
 * The higher levels take care of making this non-reentrant (it's
 * called with bh's disabled).
 */
73 74
static netdev_tx_t loopback_xmit(struct sk_buff *skb,
				 struct net_device *dev)
L
Linus Torvalds 已提交
75
{
76
	struct pcpu_lstats *lb_stats;
77
	int len;
L
Linus Torvalds 已提交
78 79 80

	skb_orphan(skb);

81
	skb->protocol = eth_type_trans(skb, dev);
L
Linus Torvalds 已提交
82

83
	/* it's OK to use per_cpu_ptr() because BHs are off */
84
	lb_stats = this_cpu_ptr(dev->lstats);
L
Linus Torvalds 已提交
85

86 87
	len = skb->len;
	if (likely(netif_rx(skb) == NET_RX_SUCCESS)) {
88
		u64_stats_update_begin(&lb_stats->syncp);
89 90
		lb_stats->bytes += len;
		lb_stats->packets++;
91
		u64_stats_update_end(&lb_stats->syncp);
92
	}
L
Linus Torvalds 已提交
93

94
	return NETDEV_TX_OK;
L
Linus Torvalds 已提交
95 96
}

97 98
static struct rtnl_link_stats64 *loopback_get_stats64(struct net_device *dev,
						      struct rtnl_link_stats64 *stats)
L
Linus Torvalds 已提交
99
{
100 101
	u64 bytes = 0;
	u64 packets = 0;
L
Linus Torvalds 已提交
102 103
	int i;

104
	for_each_possible_cpu(i) {
105
		const struct pcpu_lstats *lb_stats;
106 107
		u64 tbytes, tpackets;
		unsigned int start;
L
Linus Torvalds 已提交
108

109
		lb_stats = per_cpu_ptr(dev->lstats, i);
110 111 112 113 114 115 116
		do {
			start = u64_stats_fetch_begin(&lb_stats->syncp);
			tbytes = lb_stats->bytes;
			tpackets = lb_stats->packets;
		} while (u64_stats_fetch_retry(&lb_stats->syncp, start));
		bytes   += tbytes;
		packets += tpackets;
L
Linus Torvalds 已提交
117
	}
118 119
	stats->rx_packets = packets;
	stats->tx_packets = packets;
120 121
	stats->rx_bytes   = bytes;
	stats->tx_bytes   = bytes;
L
Linus Torvalds 已提交
122 123 124
	return stats;
}

125
static u32 always_on(struct net_device *dev)
L
Linus Torvalds 已提交
126 127 128 129
{
	return 1;
}

130
static const struct ethtool_ops loopback_ethtool_ops = {
131
	.get_link		= always_on,
L
Linus Torvalds 已提交
132 133
};

134 135
static int loopback_dev_init(struct net_device *dev)
{
136 137
	dev->lstats = alloc_percpu(struct pcpu_lstats);
	if (!dev->lstats)
138 139 140 141 142 143 144
		return -ENOMEM;

	return 0;
}

static void loopback_dev_free(struct net_device *dev)
{
145
	free_percpu(dev->lstats);
146 147 148
	free_netdev(dev);
}

149 150
static const struct net_device_ops loopback_ops = {
	.ndo_init      = loopback_dev_init,
151
	.ndo_start_xmit= loopback_xmit,
152
	.ndo_get_stats64 = loopback_get_stats64,
153 154
};

155
/*
156 157
 * The loopback device is special. There is only one instance
 * per network namespace.
158
 */
159 160 161 162 163 164 165 166
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;
167
	dev->priv_flags	       &= ~IFF_XMIT_DST_RELEASE;
168
	dev->hw_features	= NETIF_F_ALL_TSO | NETIF_F_UFO;
169
	dev->features 		= NETIF_F_SG | NETIF_F_FRAGLIST
170 171
		| NETIF_F_ALL_TSO
		| NETIF_F_UFO
172
		| NETIF_F_HW_CSUM
173
		| NETIF_F_RXCSUM
174 175
		| NETIF_F_HIGHDMA
		| NETIF_F_LLTX
176
		| NETIF_F_NETNS_LOCAL
177 178
		| NETIF_F_VLAN_CHALLENGED
		| NETIF_F_LOOPBACK;
179
	dev->ethtool_ops	= &loopback_ethtool_ops;
180
	dev->header_ops		= &eth_header_ops;
181 182
	dev->netdev_ops		= &loopback_ops;
	dev->destructor		= loopback_dev_free;
183
}
184

185
/* Setup and register the loopback device. */
186
static __net_init int loopback_net_init(struct net *net)
L
Linus Torvalds 已提交
187
{
188 189 190 191 192 193 194
	struct net_device *dev;
	int err;

	err = -ENOMEM;
	dev = alloc_netdev(0, "lo", loopback_setup);
	if (!dev)
		goto out;
195

196
	dev_net_set(dev, net);
197
	err = register_netdev(dev);
198
	if (err)
199
		goto out_free_netdev;
200

201
	net->loopback_dev = dev;
202
	return 0;
203

L
Linus Torvalds 已提交
204

205 206
out_free_netdev:
	free_netdev(dev);
207
out:
208
	if (net_eq(net, &init_net))
209 210
		panic("loopback: Failed to register netdevice: %d\n", err);
	return err;
211 212
}

213 214
/* Registered in net/core/dev.c */
struct pernet_operations __net_initdata loopback_net_ops = {
215 216
       .init = loopback_net_init,
};