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 5b77bda..808f529 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -203,7 +203,7 @@ static void inetdev_destroy(struct in_device *in_dev)
 	ASSERT_RTNL();
 
 	dev = in_dev->dev;
-	if (dev == &loopback_dev)
+	if (dev == loopback_dev)
 		return;
 
 	in_dev->dead = 1;
@@ -1058,7 +1058,7 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
 			in_dev = inetdev_init(dev);
 			if (!in_dev)
 				return notifier_from_errno(-ENOMEM);
-			if (dev == &loopback_dev) {
+			if (dev == loopback_dev) {
 				IN_DEV_CONF_SET(in_dev, NOXFRM, 1);
 				IN_DEV_CONF_SET(in_dev, NOPOLICY, 1);
 			}
@@ -1074,7 +1074,7 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
 	case NETDEV_UP:
 		if (dev->mtu < 68)
 			break;
-		if (dev == &loopback_dev) {
+		if (dev == loopback_dev) {
 			struct in_ifaddr *ifa;
 			if ((ifa = inet_alloc_ifa()) != NULL) {
 				ifa->ifa_local =
diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
index c5b2470..3ec7690 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -189,11 +189,11 @@ static int __init ic_open_devs(void)
 	rtnl_lock();
 
 	/* bring loopback device up first */
-	if (dev_change_flags(&loopback_dev, loopback_dev.flags | IFF_UP) < 0)
-		printk(KERN_ERR "IP-Config: Failed to open %s\n", loopback_dev.name);
+	if (dev_change_flags(loopback_dev, loopback_dev->flags | IFF_UP) < 0)
+		printk(KERN_ERR "IP-Config: Failed to open %s\n", loopback_dev->name);
 
 	for_each_netdev(dev) {
-		if (dev == &loopback_dev)
+		if (dev == loopback_dev)
 			continue;
 		if (user_dev_name[0] ? !strcmp(dev->name, user_dev_name) :
 		    (!(dev->flags & IFF_LOOPBACK) &&
diff --git a/net/ipv4/ipvs/ip_vs_core.c b/net/ipv4/ipvs/ip_vs_core.c
index f005a2f..7450326 100644
--- a/net/ipv4/ipvs/ip_vs_core.c
+++ b/net/ipv4/ipvs/ip_vs_core.c
@@ -961,7 +961,7 @@ ip_vs_in(unsigned int hooknum, struct sk_buff **pskb,
 	 *	... don't know why 1st test DOES NOT include 2nd (?)
 	 */
 	if (unlikely(skb->pkt_type != PACKET_HOST
-		     || skb->dev == &loopback_dev || skb->sk)) {
+		     || skb->dev == loopback_dev || skb->sk)) {
 		IP_VS_DBG(12, "packet type=%d proto=%d daddr=%d.%d.%d.%d ignored\n",
 			  skb->pkt_type,
 			  ip_hdr(skb)-

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 5b77bda..808f529 100644
>> --- a/net/ipv4/devinet.c
>> +++ b/net/ipv4/devinet.c
>> @@ -203,7 +203,7 @@ static void inetdev_destroy(struct in_device *in_dev)
>>  	ASSERT_RTNL();
>>  
>>  	dev = in_dev->dev;
>> -	if (dev == &loopback_dev)
>> +	if (dev == loopback_dev)
>>  		return;
>>  
>>  	in_dev->dead = 1;
>> @@ -1058,7 +1058,7 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
>>  			in_dev = inetdev_init(dev);
>>  			if (!in_dev)
>>  				return notifier_from_errno(-ENOMEM);
>> -			if (dev == &loopback_dev) {
>> +			if (dev == loopback_dev) {
>>  				IN_DEV_CONF_SET(in_dev, NOXFRM, 1);
>>  				IN_DEV_CONF_SET(in_dev, NOPOLICY, 1);
>>  			}
>> @@ -1074,7 +1074,7 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
>>  	case NETDEV_UP:
>>  		if (dev->mtu < 68)
>>  			break;
>> -		if (dev == &loopback_dev) {
>> +		if (dev == loopback_dev) {
>>  			struct in_ifaddr *ifa;
>>  			if ((ifa = inet_alloc_ifa()) != NULL) {
>>  				ifa->ifa_local =
>> diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
>> index c5b2470..3ec7690 100644
>> --- a/net/ipv4/ipconfig.c
>> +++ b/net/ipv4/ipconfig.c
>> @@ -189,11 +189,11 @@ static int __init ic_open_devs(void)
>>  	rtnl_lock();
>>  
>>  	/* bring loopback device up first */
>> -	if (dev_change_flags(&loopback_dev, loopback_dev.flags | IFF_UP) < 0)
>> -		printk(KERN_ERR "IP-Config: Failed to open %s\n", loopback_dev.name);
>> +	if (dev_change_flags(loopback_dev, loopback_dev->flags | IFF_UP) < 0)
>> +		printk(KERN_ERR "IP-Config: Failed to open %s\n", loopback_dev->name);
>>  
>>  	for_each_netdev(dev) {
>> -		if (dev == &loopback_dev)
>> +		if (dev == loopback_dev)
>>  			continue;
>>  		if (user_dev_name[0] ? !strcmp(dev->name, user_dev_name) :
>>  		    (!(dev->flags & IFF_LOOPBACK) &&
>> diff --git a/net/ipv4/ipvs/ip_vs_core.c b/net/ipv4/ipvs/ip_vs_core.c
>> index f005a2f..7450326 100644
>> --- a/net/ipv4/ipvs/ip_vs_core.c
>> +++ b/net/ipv4/ipvs/ip_vs_core.c
>> @@ -961,7 +961,7 @@ ip_vs_in(unsigned int hooknum, struct sk_buff **pskb,
>>  	 *	... don't know why 1st test DOES NOT include 2nd (?)
>>  	 */
>>  	if (unlikely(skb->pkt_type != PACKET_HOST
>> -		     || skb->dev == &loopback_dev || skb->sk)) {
>> +		     || skb->dev == loopback_dev || skb->sk)) {
>>  		IP_VS_DBG(12, "packet type=%d proto=%d daddr=%d.%d.%d.%d ignored\n",
>>  			  skb->pkt_type,
>>  			  ip_hdr(skb)->protocol,
>> diff --git a/net/ipv4/route.c b/net/ipv4/route.c
>> index c7ca94b..4f13385 100644
>> --- a/net/ipv4/route.c
>> +++ b/net/ipv4/route.c
>> @@ -1404,8 +1404,8 @@ static void ipv4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
>>  {
>>  	struct rtable *rt = (struct rtable *) dst;
>>  	struct in_device *idev = rt->idev;
>> -	if (dev != &loopback_dev && idev && idev->dev == dev) {
>> -		struct in_device *loopback_idev = in_dev_get(&loopback_dev);
>> +	if (dev != loopback_dev && idev && idev->dev == dev) {
>> +		struct in_device *loopback_idev = in_dev_get(loopback_dev);
>>  		if (loopback_idev) {
>>  			rt->idev = loopback_idev;
>>  			in_dev_put(idev);
>> @@ -1557,7 +1557,7 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
>>  #endif
>>  	rth->rt_iif	=
>>  	rth->fl.iif	= dev->ifindex;
>> -	rth->u.dst.dev	= &loopback_dev;
>> +	rth->u.dst.dev	= loopback_dev;
>>  	dev_hold(rth->u.dst.dev);
>>  	rth->idev	= in_dev_get(rth->u.dst.dev);
>>  	rth->fl.oif	= 0;
>> @@ -1814,7 +1814,7 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
>>  	if (res.type == RTN_LOCAL) {
>>  		int result;
>>  		result = fib_validate_source(saddr, daddr, tos,
>> -					     loopback_dev.ifindex,
>> +					     loopback_dev->ifindex,
>>  					     dev, &spec_dst, &itag);
>>  		if (result < 0)
>>  			goto martian_source;
>> @@ -1881,7 +1881,7 @@ local_input:
>>  #endif
>>  	rth->rt_iif	=
>>  	rth->fl.iif	= dev->ifindex;
>> -	rth->u.dst.dev	= &loopback_dev;
>> +	rth->u.dst.dev	= loopback_dev;
>>  	dev_hold(rth->u.dst.dev);
>>  	rth->idev	= in_dev_get(rth->u.dst.dev);
>>  	rth->rt_gateway	= daddr;
>> @@ -2151,7 +2151,7 @@ static int ip_route_output_slow(struct rtable **rp, const struct flowi *oldflp)
>>  						  RT_SCOPE_UNIVERSE),
>>  				      } },
>>  			    .mark = oldflp->mark,
>> -			    .iif = loopback_dev.ifindex,
>> +			    .iif = loopback_dev->ifindex,
>>  			    .oif = oldflp->oif };
>>  	struct fib_result res;
>>  	unsigned flags = 0;
>> @@ -2245,9 +2245,9 @@ static int ip_route_output_slow(struct rtable **rp, const struct flowi *oldflp)
>>  			fl.fl4_dst = fl.fl4_src = htonl(INADDR_LOOPBACK);
>>  		if (dev_out)
>>  			dev_put(dev_out);
>> -		dev_out = &loopback_dev;
>> +		dev_out = loopback_dev;
>>  		dev_hold(dev_out);
>> -		fl.oif = loopback_dev.ifindex;
>> +		fl.oif = loopback_dev->ifindex;
>>  		res.type = RTN_LOCAL;
>>  		flags |= RTCF_LOCAL;
>>  		goto make_route;
>> @@ -2292,7 +2292,7 @@ static int ip_route_output_slow(struct rtable **rp, const struct flowi *oldflp)
>>  			fl.fl4_src = fl.fl4_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/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
>> index 4ff8ed3..29ab3de 100644
>> --- a/net/ipv4/xfrm4_policy.c
>> +++ b/net/ipv4/xfrm4_policy.c
>> @@ -306,7 +306,7 @@ static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
>>  
>>  	xdst = (struct xfrm_dst *)dst;
>>  	if (xdst->u.rt.idev->dev == dev) {
>> -		struct in_device *loopback_idev = in_dev_get(&loopback_dev);
>> +		struct in_device *loopback_idev = in_dev_get(loopback_dev);
>>  		BUG_ON(!loopback_idev);
>>  
>>  		do {
>> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
>> index 91ef3be..d806f89 100644
>> --- a/net/ipv6/addrconf.c
>> +++ b/net/ipv6/addrconf.c
>> @@ -2399,7 +2399,7 @@ static int addrconf_ifdown(struct net_device *dev, int how)
>>  
>>  	ASSERT_RTNL();
>>  
>> -	if (dev == &loopback_dev && how == 1)
>> +	if (dev == loopback_dev && how == 1)
>>  		how = 0;
>>  
>>  	rt6_ifdown(dev);
>> @@ -4203,16 +4203,19 @@ int __init addrconf_init(void)
>>  	 * device and it being up should be removed.
>>  	 */
>>  	rtnl_lock();
>> -	if (!ipv6_add_dev(&loopback_dev))
>> +	if (!ipv6_add_dev(loopback_dev))
>>  		err = -ENOMEM;
>>  	rtnl_unlock();
>>  	if (err)
>>  		return err;
>>  
>> -	ip6_null_entry.rt6i_idev = in6_dev_get(&loopback_dev);
>> +	ip6_null_entry.u.dst.dev = loopback_dev;
>> +	ip6_null_entry.rt6i_idev = in6_dev_get(loopback_dev);
>>  #ifdef CONFIG_IPV6_MULTIPLE_TABLES
>> -	ip6_prohibit_entry.rt6i_idev = in6_dev_get(&loopback_dev);
>> -	ip6_blk_hole_entry.rt6i_idev = in6_dev_get(&loopback_dev);
>> +	ip6_prohibit_entry.u.dst.dev = loopback_dev;
>> +	ip6_prohibit_entry.rt6i_idev = in6_dev_get(loopback_dev);
>> +	ip6_blk_hole_entry.u.dst.dev = loopback_dev;
>> +	ip6_blk_hole_entry.rt6i_idev = in6_dev_get(loopback_dev);
>>  #endif
>>  
>>  	register_netdevice_notifier(&ipv6_dev_notf);
>> @@ -4267,7 +4270,7 @@ void __exit addrconf_cleanup(void)
>>  			continue;
>>  		addrconf_ifdown(dev, 1);
>>  	}
>> -	addrconf_ifdown(&loopback_dev, 2);
>> +	addrconf_ifdown(loopback_dev, 2);
>>  
>>  	/*
>>  	 *	Check hash table.
>> diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
>> index 30a5cb1..15d7910 100644
>> --- a/net/ipv6/ip6_input.c
>> +++ b/net/ipv6/ip6_input.c
>> @@ -86,7 +86,7 @@ int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt
>>  	 *
>>  	 * BTW, when we send a packet for our own local address on a
>>  	 * non-loopback interface (e.g. ethX), it is being delivered
>> -	 * via the loopback interface (lo) here; skb->dev = &loopback_dev.
>> +	 * via the loopback interface (lo) here; skb->dev = loopback_dev.
>>  	 * It, however, should be considered as if it is being
>>  	 * arrived via the sending interface (ethX), because of the
>>  	 * nature of scoping architecture. --yoshfuji
>> diff --git a/net/ipv6/netfilter/ip6t_REJECT.c b/net/ipv6/netfilter/ip6t_REJECT.c
>> index 2f487cd..5086053 100644
>> --- a/net/ipv6/netfilter/ip6t_REJECT.c
>> +++ b/net/ipv6/netfilter/ip6t_REJECT.c
>> @@ -167,7 +167,7 @@ static inline void
>>  send_unreach(struct sk_buff *skb_in, unsigned char code, unsigned int hooknum)
>>  {
>>  	if (hooknum == NF_IP6_LOCAL_OUT && skb_in->dev == NULL)
>> -		skb_in->dev = &loopback_dev;
>> +		skb_in->dev = loopback_dev;
>>  
>>  	icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0, NULL);
>>  }
>> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
>> index 55ea80f..3f5c65f 100644
>> --- a/net/ipv6/route.c
>> +++ b/net/ipv6/route.c
>> @@ -137,7 +137,6 @@ struct rt6_info ip6_null_entry = {
>>  		.dst = {
>>  			.__refcnt	= ATOMIC_INIT(1),
>>  			.__use		= 1,
>> -			.dev		= &loopback_dev,
>>  			.obsolete	= -1,
>>  			.error		= -ENETUNREACH,
>>  			.metrics	= { [RTAX_HOPLIMIT - 1] = 255, },
>> @@ -163,7 +162,6 @@ struct rt6_info ip6_prohibit_entry = {
>>  		.dst = {
>>  			.__refcnt	= ATOMIC_INIT(1),
>>  			.__use		= 1,
>> -			.dev		= &loopback_dev,
>>  			.obsolete	= -1,
>>  			.error		= -EACCES,
>>  			.metrics	= { [RTAX_HOPLIMIT - 1] = 255, },
>> @@ -183,7 +181,6 @@ struct rt6_info ip6_blk_hole_entry = {
>>  		.dst = {
>>  			.__refcnt	= ATOMIC_INIT(1),
>>  			.__use		= 1,
>> -			.dev		= &loopback_dev,
>>  			.obsolete	= -1,
>>  			.error		= -EINVAL,
>>  			.metrics	= { [RTAX_HOPLIMIT - 1] = 255, },
>> @@ -223,8 +220,8 @@ static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
>>  	struct rt6_info *rt = (struct rt6_info *)dst;
>>  	struct inet6_dev *idev = rt->rt6i_idev;
>>  
>> -	if (dev != &loopback_dev && idev != NULL && idev->dev == dev) {
>> -		struct inet6_dev *loopback_idev = in6_dev_get(&loopback_dev);
>> +	if (dev != loopback_dev && idev != NULL && idev->dev == dev) {
>> +		struct inet6_dev *loopback_idev = in6_dev_get(loopback_dev);
>>  		if (loopback_idev != NULL) {
>>  			rt->rt6i_idev = loopback_idev;
>>  			in6_dev_put(idev);
>> @@ -1187,12 +1184,12 @@ int ip6_route_add(struct fib6_config *cfg)
>>  	if ((cfg->fc_flags & RTF_REJECT) ||
>>  	    (dev && (dev->flags&IFF_LOOPBACK) && !(addr_type&IPV6_ADDR_LOOPBACK))) {
>>  		/* hold loopback dev/idev if we haven't done so. */
>> -		if (dev != &loopback_dev) {
>> +		if (dev != loopback_dev) {
>>  			if (dev) {
>>  				dev_put(dev);
>>  				in6_dev_put(idev);
>>  			}
>> -			dev = &loopback_dev;
>> +			dev = loopback_dev;
>>  			dev_hold(dev);
>>  			idev = in6_dev_get(dev);
>>  			if (!idev) {
>> @@ -1896,13 +1893,13 @@ struct rt6_info *addrconf_dst_alloc(struct inet6_dev *idev,
>>  	if (rt == NULL)
>>  		return ERR_PTR(-ENOMEM);
>>  
>> -	dev_hold(&loopback_dev);
>> +	dev_hold(loopback_dev);
>>  	in6_dev_hold(idev);
>>  
>>  	rt->u.dst.flags = DST_HOST;
>>  	rt->u.dst.input = ip6_input;
>>  	rt->u.dst.output = ip6_output;
>> -	rt->rt6i_dev = &loopback_dev;
>> +	rt->rt6i_dev = loopback_dev;
>>  	rt->rt6i_idev = idev;
>>  	rt->u.dst.metrics[RTAX_MTU-1] = ipv6_get_mtu(rt->rt6i_dev);
>>  	rt->u.dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(dst_mtu(&rt->u.dst));
>> diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
>> index 3ec0c47..cc07216 100644
>> --- a/net/ipv6/xfrm6_policy.c
>> +++ b/net/ipv6/xfrm6_policy.c
>> @@ -375,7 +375,7 @@ static void xfrm6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
>>  
>>  	xdst = (struct xfrm_dst *)dst;
>>  	if (xdst->u.rt6.rt6i_idev->dev == dev) {
>> -		struct inet6_dev *loopback_idev = in6_dev_get(&loopback_dev);
>> +		struct inet6_dev *loopback_idev = in6_dev_get(loopback_dev);
>>  		BUG_ON(!loopback_idev);
>>  
>>  		do {
>> diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
>> index c7b2503..ca37eec 100644
>> --- a/net/xfrm/xfrm_policy.c
>> +++ b/net/xfrm/xfrm_policy.c
>> @@ -1947,8 +1947,8 @@ static int stale_bundle(struct dst_entry *dst)
>>  void xfrm_dst_ifdown(struct dst_entry *dst, struct net_device *dev)
>>  {
>>  	while ((dst = dst->child) && dst->xfrm && dst->dev == dev) {
>> -		dst->dev = &loopback_dev;
>> -		dev_hold(&loopback_dev);
>> +		dst->dev = loopback_dev;
>> +		dev_hold(dst->dev);
>>  		dev_put(dev);
>>  	}
>>  }
> 
> _______________________________________________
> Containers mailing list
> Containers@lists.linux-foundation.org
> https://lists.linux-foundation.org/mailman/listinfo/containers
> 


-- 
B e n j a m i n   T h e r y  - BULL/DT/Open Software R&D

    http://www.bull.com
_______________________________________________
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Acked-By: Kirill Korotaev <dev@sw.ru>

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 5b77bda..808f529 100644
> --- a/net/ipv4/devinet.c
> +++ b/net/ipv4/devinet.c
> @@ -203,7 +203,7 @@ static void inetdev_destroy(struct in_device *in_dev)
>  	ASSERT_RTNL();
>  
>  	dev = in_dev->dev;
> -	if (dev == &loopback_dev)
> +	if (dev == loopback_dev)
>  		return;
>  
>  	in_dev->dead = 1;
> @@ -1058,7 +1058,7 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
>  			in_dev = inetdev_init(dev);
>  			if (!in_dev)
>  				return notifier_from_errno(-ENOMEM);
> -			if (dev == &loopback_dev) {
> +			if (dev == loopback_dev) {
>  				IN_DEV_CONF_SET(in_dev, NOXFRM, 1);
>  				IN_DEV_CONF_SET(in_dev, NOPOLICY, 1);
>  			}
> @@ -1074,7 +1074,7 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
>  	case NETDEV_UP:
>  		if (dev->mtu < 68)
>  			break;
> -		if (dev == &loopback_dev) {
> +		if (dev == loopback_dev) {
>  			struct in_ifaddr *ifa;
>  			if ((ifa = inet_alloc_ifa()) != NULL) {
>  				ifa->ifa_local