Kirill Korotaev wrote:
> Acked-By: Kirill Korotaev <dev@sw.ru>

Acked-by: Benjamin Thery <benjamin.thery@bull.net>

Looks good to me.
Compiled and tested on i386.

> 
> dlezcano@fr.ibm.com wrote:
>> From: Daniel Lezcano <dlezcano@fr.ibm.com>
>>
>> Doing this makes loopback.c a better example of how to do a
>> simple network device, and it removes the special case
>> single static allocation of a struct net_device, hopefully
>> making maintenance easier.
>>
>> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
>> Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
>> ---
>>  drivers/net/loopback.c           |   63 +++++++++++++++++++++++---------------
>>  include/linux/netdevice.h        |    2 +-
>>  net/core/dst.c                   |    8 ++--
>>  net/decnet/dn_dev.c              |    4 +-
>>  net/decnet/dn_route.c            |   14 ++++----
>>  net/ipv4/devinet.c               |    6 ++--
>>  net/ipv4/ipconfig.c              |    6 ++--
>>  net/ipv4/ipvs/ip_vs_core.c       |    2 +-
>>  net/ipv4/route.c                 |   18 +++++-----
>>  net/ipv4/xfrm4_policy.c          |    2 +-
>>  net/ipv6/addrconf.c              |   15 +++++---
>>  net/ipv6/ip6_input.c             |    2 +-
>>  net/ipv6/netfilter/ip6t_REJECT.c |    2 +-
>>  net/ipv6/route.c                 |   15 +++-----
>>  net/ipv6/xfrm6_policy.c          |    2 +-
>>  net/xfrm/xfrm_policy.c           |    4 +-
>>  16 files changed, 89 insertions(+), 76 deletions(-)
>>
>> diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
>> index 5106c23..3642aff 100644
>> --- a/drivers/net/loopback.c
>> +++ b/drivers/net/loopback.c
>> @@ -199,44 +199,57 @@ static const struct ethtool_ops loopback_ethtool_ops = {
>>  	.get_rx_csum		= always_on,
>>  };
>>  
>> -/*
>> - * The loopback device is special. There is only one instance and
>> - * it is statically allocated. Don't do this for other devices.
>> - */
>> -struct net_device loopback_dev = {
>> -	.name	 		= "lo",
>> -	.get_stats		= &get_stats,
>> -	.mtu			= (16 * 1024) + 20 + 20 + 12,
>> -	.hard_start_xmit	= loopback_xmit,
>> -	.hard_header		= eth_header,
>> -	.hard_header_cache	= eth_header_cache,
>> -	.header_cache_update	= eth_header_cache_update,
>> -	.hard_header_len	= ETH_HLEN,	/* 14	*/
>> -	.addr_len		= ETH_ALEN,	/* 6	*/
>> -	.tx_queue_len		= 0,
>> -	.type			= ARPHRD_LOOPBACK,	/* 0x0001*/
>> -	.rebuild_header		= eth_rebuild_header,
>> -	.flags			= IFF_LOOPBACK,
>> -	.features 		= NETIF_F_SG | NETIF_F_FRAGLIST
>> +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	= eth_header;
>> +	dev->hard_header_cache	= eth_header_cache;
>> +	dev->header_cache_update = eth_header_cache_update;
>> +	dev->hard_header_len	= ETH_HLEN;	/* 14	*/
>> +	dev->addr_len		= ETH_ALEN;	/* 6	*/
>> +	dev->tx_queue_len	= 0;
>> +	dev->type		= ARPHRD_LOOPBACK;	/* 0x0001*/
>> +	dev->rebuild_header	= eth_rebuild_header;
>> +	dev->flags		= IFF_LOOPBACK;
>> +	dev->features 		= NETIF_F_SG | NETIF_F_FRAGLIST
>>  #ifdef LOOPBACK_TSO
>>  				  | NETIF_F_TSO
>>  #endif
>>  				  | NETIF_F_NO_CSUM | NETIF_F_HIGHDMA
>> -				  | NETIF_F_LLTX,
>> -	.ethtool_ops		= &loopback_ethtool_ops,
>> -};
>> +				  | NETIF_F_LLTX;
>> +	dev->ethtool_ops	= &loopback_ethtool_ops;
>> +}
>>  
>>  /* Setup and register the loopback device. */
>>  static int __init loopback_init(void)
>>  {
>> -	int err = register_netdev(&loopback_dev);
>> +	struct net_device *dev;
>> +	int err;
>> +	
>> +	err = -ENOMEM;
>> +	dev = alloc_netdev(0, "lo", loopback_setup);
>> +	if (!dev)
>> +		goto out;
>> +
>> +	err = register_netdev(dev);
>> +	if (err)
>> +		goto out_free_netdev;
>>  
>> +	err = 0;
>> +	loopback_dev = dev;
>> +
>> +out:
>>  	if (err)
>>  		panic("loopback: Failed to register netdevice: %d\n", err);
>> -
>>  	return err;
>> +out_free_netdev:
>> +	free_netdev(dev);
>> +	goto out;
>>  };
>>  
>> -module_init(loopback_init);
>> +fs_initcall(loopback_init);
>>  
>> +struct net_device *loopback_dev;
>>  EXPORT_SYMBOL(loopback_dev);
>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>> index 8d12f02..7cd0641 100644
>> --- a/include/linux/netdevice.h
>> +++ b/include/linux/netdevice.h
>> @@ -680,7 +680,7 @@ struct packet_type {
>>  #include <linux/interrupt.h>
>>  #include <linux/notifier.h>
>>  
>> -extern struct net_device		loopback_dev;		/* The loopback */
>> +extern struct net_device		*loopback_dev;		/* The loopback */
>>  extern struct list_head			dev_base_head;		/* All devices */
>>  extern rwlock_t				dev_base_lock;		/* Device list lock */
>>  
>> diff --git a/net/core/dst.c b/net/core/dst.c
>> index c6a0587..ad8549e 100644
>> --- a/net/core/dst.c
>> +++ b/net/core/dst.c
>> @@ -236,13 +236,13 @@ static inline void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
>>  	if (!unregister) {
>>  		dst->input = dst->output = dst_discard;
>>  	} else {
>> -		dst->dev = &loopback_dev;
>> -		dev_hold(&loopback_dev);
>> +		dst->dev = loopback_dev;
>> +		dev_hold(dst->dev);
>>  		dev_put(dev);
>>  		if (dst->neighbour && dst->neighbour->dev == dev) {
>> -			dst->neighbour->dev = &loopback_dev;
>> +			dst->neighbour->dev = loopback_dev;
>>  			dev_put(dev);
>> -			dev_hold(&loopback_dev);
>> +			dev_hold(dst->neighbour->dev);
>>  		}
>>  	}
>>  }
>> diff --git a/net/decnet/dn_dev.c b/net/decnet/dn_dev.c
>> index fa6604f..9fea83e 100644
>> --- a/net/decnet/dn_dev.c
>> +++ b/net/decnet/dn_dev.c
>> @@ -868,10 +868,10 @@ last_chance:
>>  		rv = dn_dev_get_first(dev, addr);
>>  		read_unlock(&dev_base_lock);
>>  		dev_put(dev);
>> -		if (rv == 0 || dev == &loopback_dev)
>> +		if (rv == 0 || dev == loopback_dev)
>>  			return rv;
>>  	}
>> -	dev = &loopback_dev;
>> +	dev = loopback_dev;
>>  	dev_hold(dev);
>>  	goto last_chance;
>>  }
>> diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
>> index a4a6209..8c04ebc 100644
>> --- a/net/decnet/dn_route.c
>> +++ b/net/decnet/dn_route.c
>> @@ -883,7 +883,7 @@ static int dn_route_output_slow(struct dst_entry **pprt, const struct flowi *old
>>  					.scope = RT_SCOPE_UNIVERSE,
>>  				     } },
>>  			    .mark = oldflp->mark,
>> -			    .iif = loopback_dev.ifindex,
>> +			    .iif = loopback_dev->ifindex,
>>  			    .oif = oldflp->oif };
>>  	struct dn_route *rt = NULL;
>>  	struct net_device *dev_out = NULL, *dev;
>> @@ -900,7 +900,7 @@ static int dn_route_output_slow(struct dst_entry **pprt, const struct flowi *old
>>  		       "dn_route_output_slow: dst=%04x src=%04x mark=%d"
>>  		       " iif=%d oif=%d\n", dn_ntohs(oldflp->fld_dst),
>>  		       dn_ntohs(oldflp->fld_src),
>> -		       oldflp->mark, loopback_dev.ifindex, oldflp->oif);
>> +		       oldflp->mark, loopback_dev->ifindex, oldflp->oif);
>>  
>>  	/* If we have an output interface, verify its a DECnet device */
>>  	if (oldflp->oif) {
>> @@ -953,7 +953,7 @@ source_ok:
>>  		err = -EADDRNOTAVAIL;
>>  		if (dev_out)
>>  			dev_put(dev_out);
>> -		dev_out = &loopback_dev;
>> +		dev_out = loopback_dev;
>>  		dev_hold(dev_out);
>>  		if (!fl.fld_dst) {
>>  			fl.fld_dst =
>> @@ -962,7 +962,7 @@ source_ok:
>>  			if (!fl.fld_dst)
>>  				goto out;
>>  		}
>> -		fl.oif = loopback_dev.ifindex;
>> +		fl.oif = loopback_dev->ifindex;
>>  		res.type = RTN_LOCAL;
>>  		goto make_route;
>>  	}
>> @@ -1008,7 +1008,7 @@ source_ok:
>>  					if (dev_out)
>>  						dev_put(dev_out);
>>  					if (dn_dev_islocal(neigh->dev, fl.fld_dst)) {
>> -						dev_out = &loopback_dev;
>> +						dev_out = loopback_dev;
>>  						res.type = RTN_LOCAL;
>>  					} else {
>>  						dev_out = neigh->dev;
>> @@ -1029,7 +1029,7 @@ source_ok:
>>  		/* Possible improvement - check all devices for local addr */
>>  		if (dn_dev_islocal(dev_out, fl.fld_dst)) {
>>  			dev_put(dev_out);
>> -			dev_out = &loopback_dev;
>> +			dev_out = loopback_dev;
>>  			dev_hold(dev_out);
>>  			res.type = RTN_LOCAL;
>>  			goto select_source;
>> @@ -1065,7 +1065,7 @@ select_source:
>>  			fl.fld_src = fl.fld_dst;
>>  		if (dev_out)
>>  			dev_put(dev_out);
>> -		dev_out = &loopback_dev;
>> +		dev_out = loopback_dev;
>>  		dev_hold(dev_out);
>>  		fl.oif = dev_out->ifindex;
>>  		if (res.fi)
>> diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
>> index 5b