kevin/linux
1
Fork 0
Code
2377989754
linux/drivers/net/loopback.c
Eric W. Biederman 505d4f73dd net: Guaranetee the proper ordering of the loopback device. v2 
I was recently hunting a bug that occurred in network namespace
cleanup.  In looking at the code it became apparrent that we have
and will continue to have cases where if we have anything going
on in a network namespace there will be assumptions that the
loopback device is present.   Things like sending igmp unsubscribe
messages when we bring down network devices invokes the routing
code which assumes that at least the loopback driver is present.

Therefore to avoid magic initcall ordering hackery that is hard
to follow and hard to get right insert a call to register the
loopback device directly from net_dev_init().    This guarantes
that the loopback device is the first device registered and
the last network device to go away.

But do it carefully so we register the loopback device after
we clear dev_boot_phase.

Signed-off-by: Eric W. Biederman <ebiederm@maxwell.aristanetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-07 22:54:20 -08:00

212 lines
5.1 KiB
C
Raw Blame History

/*
* 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;
};
/*
* 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;
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());
lb_stats->bytes += skb->len;
lb_stats->packets++;
netif_rx(skb);
return 0;
}
static struct net_device_stats *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;
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;
}
stats->rx_packets = packets;
stats->tx_packets = packets;
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);
}
/*
* The loopback device is special. There is only one instance
* per network namespace.
*/
static void loopback_setup(struct net_device *dev)
{
dev->get_stats = &get_stats;
dev->mtu = (16 * 1024) + 20 + 20 + 12;
dev->hard_start_xmit = loopback_xmit;
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->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 = &eth_header_ops;
dev->init = loopback_dev_init;
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,
};
View Git Blame Copy Permalink