Release 4.11 drivers/net/loopback.c

/*
 * 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/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>
#include <linux/u64_stats_sync.h>


struct pcpu_lstats {
	
u64			packets;
	
u64			bytes;
	
struct u64_stats_sync	syncp;
};

/*
 * The higher levels take care of making this non-reentrant (it's
 * called with bh's disabled).
 */


static netdev_tx_t loopback_xmit(struct sk_buff *skb,
				 struct net_device *dev)
{
	struct pcpu_lstats *lb_stats;
	int len;

	skb_orphan(skb);

	/* Before queueing this packet to netif_rx(),
         * make sure dst is refcounted.
         */
	skb_dst_force(skb);

	skb->protocol = eth_type_trans(skb, dev);

	/* it's OK to use per_cpu_ptr() because BHs are off */
	lb_stats = this_cpu_ptr(dev->lstats);

	len = skb->len;
	if (likely(netif_rx(skb) == NET_RX_SUCCESS)) {
		u64_stats_update_begin(&lb_stats->syncp);
		lb_stats->bytes += len;
		lb_stats->packets++;
		u64_stats_update_end(&lb_stats->syncp);
	}

	return NETDEV_TX_OK;
}

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Eric Dumazet
51
48.11%
6
31.58%
Linus Torvalds (pre-git)
40
37.74%
6
31.58%
Andrew Morton
8
7.55%
1
5.26%
Arthur Kepner
2
1.89%
1
5.26%
Eric W. Biedermann
2
1.89%
2
10.53%
Stephen Hemminger
1
0.94%
1
5.26%
Christoph Lameter
1
0.94%
1
5.26%
Patrick McHardy
1
0.94%
1
5.26%
Total
106
100.00%
19
100.00%



static void loopback_get_stats64(struct net_device *dev,
				 struct rtnl_link_stats64 *stats)
{
	u64 bytes = 0;
	u64 packets = 0;
	int i;

	for_each_possible_cpu(i) {
		const struct pcpu_lstats *lb_stats;
		u64 tbytes, tpackets;
		unsigned int start;

		lb_stats = per_cpu_ptr(dev->lstats, i);
		do {
			start = u64_stats_fetch_begin_irq(&lb_stats->syncp);
			tbytes = lb_stats->bytes;
			tpackets = lb_stats->packets;
		} while (u64_stats_fetch_retry_irq(&lb_stats->syncp, start));
		bytes   += tbytes;
		packets += tpackets;
	}
	stats->rx_packets = packets;
	stats->tx_packets = packets;
	stats->rx_bytes   = bytes;
	stats->tx_bytes   = bytes;
}

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Eric Dumazet
89
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5
33.33%
Arthur Kepner
17
12.98%
2
13.33%
Andrew Morton
11
8.40%
2
13.33%
Linus Torvalds (pre-git)
9
6.87%
2
13.33%
Eric W. Biedermann
3
2.29%
2
13.33%
Stephen Hemminger
1
0.76%
1
6.67%
Kamezawa Hiroyuki
1
0.76%
1
6.67%
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131
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15
100.00%



static u32 always_on(struct net_device *dev)
{
	return 1;
}

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David S. Miller
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33.33%
Adrian Bunk
1
7.14%
1
33.33%
Stephen Hemminger
1
7.14%
1
33.33%
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14
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3
100.00%


static const struct ethtool_ops loopback_ethtool_ops = {
	.get_link		= always_on,
};



static int loopback_dev_init(struct net_device *dev)
{
	dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
	if (!dev->lstats)
		return -ENOMEM;
	return 0;
}

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Eric W. Biedermann
30
85.71%
1
33.33%
Eric Dumazet
4
11.43%
1
33.33%
Américo Wang
1
2.86%
1
33.33%
Total
35
100.00%
3
100.00%



static void loopback_dev_free(struct net_device *dev)
{
	dev_net(dev)->loopback_dev = NULL;
	free_percpu(dev->lstats);
	free_netdev(dev);
}

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66.67%
Eric Dumazet
2
6.25%
1
33.33%
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32
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3
100.00%


static const struct net_device_ops loopback_ops = {
	.ndo_init      = loopback_dev_init,
	.ndo_start_xmit= loopback_xmit,
	.ndo_get_stats64 = loopback_get_stats64,
	.ndo_set_mac_address = eth_mac_addr,
};

/*
 * The loopback device is special. There is only one instance
 * per network namespace.
 */


static void loopback_setup(struct net_device *dev)
{
	dev->mtu		= 64 * 1024;
	dev->hard_header_len	= ETH_HLEN;	/* 14   */
	dev->min_header_len	= ETH_HLEN;	/* 14   */
	dev->addr_len		= ETH_ALEN;	/* 6    */
	dev->type		= ARPHRD_LOOPBACK;	/* 0x0001*/
	dev->flags		= IFF_LOOPBACK;
	dev->priv_flags		|= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE;
	netif_keep_dst(dev);
	dev->hw_features	= NETIF_F_GSO_SOFTWARE;
	dev->features 		= NETIF_F_SG | NETIF_F_FRAGLIST
		| NETIF_F_GSO_SOFTWARE
		| NETIF_F_HW_CSUM
		| NETIF_F_RXCSUM
		| NETIF_F_SCTP_CRC
		| NETIF_F_HIGHDMA
		| NETIF_F_LLTX
		| NETIF_F_NETNS_LOCAL
		| NETIF_F_VLAN_CHALLENGED
		| NETIF_F_LOOPBACK;
	dev->ethtool_ops	= &loopback_ethtool_ops;
	dev->header_ops		= &eth_header_ops;
	dev->netdev_ops		= &loopback_ops;
	dev->destructor		= loopback_dev_free;
}

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17
13.60%
5
17.24%
Stephen Hemminger
13
10.40%
3
10.34%
Eric W. Biedermann
12
9.60%
2
6.90%
Linus Torvalds
10
8.00%
1
3.45%
Michał Mirosław
8
6.40%
2
6.90%
Eric Dumazet
8
6.40%
3
10.34%
Willem de Bruijn
7
5.60%
1
3.45%
Américo Wang
4
3.20%
1
3.45%
David S. Miller
4
3.20%
1
3.45%
Phil Sutter
2
1.60%
1
3.45%
Mahesh Bandewar
2
1.60%
1
3.45%
Arthur Kepner
2
1.60%
1
3.45%
Krishna Kumar
2
1.60%
1
3.45%
Marcelo Ricardo Leitner
2
1.60%
1
3.45%
Tom Herbert
1
0.80%
1
3.45%
Chuck Ebbert
1
0.80%
1
3.45%
Emil Medve
1
0.80%
1
3.45%
Daniel Borkmann
1
0.80%
1
3.45%
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125
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29
100.00%

/* 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", NET_NAME_UNKNOWN, loopback_setup);
	if (!dev)
		goto out;

	dev_net_set(dev, net);
	err = register_netdev(dev);
	if (err)
		goto out_free_netdev;

	BUG_ON(dev->ifindex != LOOPBACK_IFINDEX);
	net->loopback_dev = dev;
	return 0;


out_free_netdev:
	free_netdev(dev);
out:
	if (net_eq(net, &init_net))
		panic("loopback: Failed to register netdevice: %d\n", err);
	return err;
}

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Herbert Xu
14
12.28%
1
7.69%
Eric W. Biedermann
10
8.77%
1
7.69%
Stephen Hemminger
7
6.14%
1
7.69%
Octavian Purdila
4
3.51%
1
7.69%
Hideaki Yoshifuji / 吉藤英明
4
3.51%
1
7.69%
Tom Gundersen
2
1.75%
1
7.69%
Linus Torvalds (pre-git)
2
1.75%
2
15.38%
Adrian Bunk
1
0.88%
1
7.69%
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/* Registered in net/core/dev.c */

struct pernet_operations __net_initdata loopback_net_ops = {
       .init = loopback_net_init,
};
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126
17.67%
16
20.00%
Eric W. Biedermann
101
14.17%
7
8.75%
Daniel Lezcano
77
10.80%
1
1.25%
Stephen Hemminger
45
6.31%
7
8.75%
David S. Miller
30
4.21%
1
1.25%
Pavel Emelyanov
23
3.23%
3
3.75%
Andrew Morton
22
3.09%
2
2.50%
Arthur Kepner
21
2.95%
2
2.50%
Herbert Xu
14
1.96%
1
1.25%
Linus Torvalds
11
1.54%
2
2.50%
Américo Wang
10
1.40%
2
2.50%
Alexey Kuznetsov
9
1.26%
1
1.25%
Michał Mirosław
8
1.12%
2
2.50%
Willem de Bruijn
7
0.98%
1
1.25%
Octavian Purdila
4
0.56%
1
1.25%
Hideaki Yoshifuji / 吉藤英明
4
0.56%
1
1.25%
Arnaldo Carvalho de Melo
3
0.42%
1
1.25%
Phil Sutter
2
0.28%
1
1.25%
Adrian Bunk
2
0.28%
2
2.50%
Krishna Kumar
2
0.28%
1
1.25%
Marcelo Ricardo Leitner
2
0.28%
1
1.25%
Mahesh Bandewar
2
0.28%
1
1.25%
Tom Gundersen
2
0.28%
1
1.25%
Patrick McHardy
1
0.14%
1
1.25%
Ralf Bächle
1
0.14%
1
1.25%
Chuck Ebbert
1
0.14%
1
1.25%
Emil Medve
1
0.14%
1
1.25%
Jeff Garzik
1
0.14%
1
1.25%
Jesper Juhl
1
0.14%
1
1.25%
Denis V. Lunev
1
0.14%
1
1.25%
Tom Herbert
1
0.14%
1
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Kamezawa Hiroyuki
1
0.14%
1
1.25%
Daniel Borkmann
1
0.14%
1
1.25%
Christoph Lameter
1
0.14%
1
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Rusty Russell
1
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80
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Directory: drivers/net

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