From: Eric W. Biederman <ebiederm@xmission.com> - unquoted

This patch makes the loopback_dev per network namespace.
The loopback device registers itself as a pernet_device so
we can register the new loopback_dev instance when we add
a new network namespace and so we can unregister the
loopback device when we destory the network namespace.

Currently the loopback device statitics are kept accross
all loopback devices, a minor glitch that will not affect
correct operation but something we may want to fix.

This patch modifies all users the loopback_dev so they
access it as per_net(loopback_dev, init_net()), keeping all of the
code compiling and working.  A later pass will be needed to
update the users to use something other than the initial network
namespace.

The only non-trivial modification was the ipv6 code in route.c as the
loopback_dev can no longer be used in static initializers, and
even that change was very simple.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 drivers/net/loopback.c           |   24 ++++++++++++++++++++----
 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               |    4 ++--
 net/ipv4/ipconfig.c              |    8 +++++---
 net/ipv4/ipvs/ip_vs_core.c       |    2 +-
 net/ipv4/route.c                 |   18 +++++++++---------
 net/ipv4/xfrm4_policy.c          |    2 +-
 net/ipv6/addrconf.c              |    8 ++++----
 net/ipv6/netfilter/ip6t_REJECT.c |    2 +-
 net/ipv6/route.c                 |   24 +++++++++++++++---------
 net/ipv6/xfrm6_policy.c          |    2 +-
 net/xfrm/xfrm_policy.c           |    4 ++--
 15 files changed, 75 insertions(+), 51 deletions(-)

diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index 22b672d..e9abf3f 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -57,6 +57,7 @@
 #include <linux/ip.h>
 #include <linux/tcp.h>
 #include <linux/percpu.h>
+#include <net/net_namespace.h>
 
 struct pcpu_lstats {
 	unsigned long packets;
@@ -204,7 +205,7 @@ static const struct ethtool_ops loopback_ethtool_ops = {
  * 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 = {
+DEFINE_PER_NET(struct net_device, loopback_dev) = {
 	.name	 		= "lo",
 	.get_stats		= &get_stats,
 	.priv			= &loopback_stats,
@@ -228,13 +229,28 @@ struct net_device loopback_dev = {
 	.ethtool_ops		= &loopback_ethtool_ops,
 };
 
+static int loopback_net_init(net_t net)
+{
+	per_net(loopback_dev, net).nd_net = net;
+	return register_netdev(&per_net(loopback_dev, net));
+}
+
+static void loopback_net_exit(net_t net)
+{
+	unregister_netdev(&per_net(loopback_dev, net));
+}
+
+static struct pernet_operations loopback_net_ops = {
+	.init = loopback_net_init,
+	.exit = loopback_net_exit,
+};
+
 /* Setup and register the loopback device. */
 static int __init loopback_init(void)
 {
-	loopback_dev.nd_net = init_net();
-	return register_netdev(&loopback_dev);
+	return register_pernet_device(&loopback_net_ops);
 };
 
 module_init(loopback_init);
 
-EXPORT_SYMBOL(loopback_dev);
+EXPORT_PER_NET_SYMBOL(loopback_dev);
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 9e28671..73931a0 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -570,7 +570,7 @@ struct packet_type {
 #include <linux/interrupt.h>
 #include <linux/notifier.h>
 
-extern struct net_device		loopback_dev;		/* The loopback */
+DECLARE_PER_NET(struct net_device,	loopback_dev);		/* The loopback */
 extern struct net_device		*dev_base;		/* All devices */
 extern rwlock_t				dev_base_lock;		/* Device list lock */
 
diff --git a/net/core/dst.c b/net/core/dst.c
index 8c4a272..3435771 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -241,13 +241,13 @@ static inline void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 		dst->input = dst_discard_in;
 		dst->output = dst_discard_out;
 	} else {
-		dst->dev = &loopback_dev;
-		dev_hold(&loopback_dev);
+		dst->dev = &per_net(loopback_dev, init_net());
+		dev_hold(dst->dev);
 		dev_put(dev);
 		if (dst->neighbour && dst->neighbour->dev == dev) {
-			dst->neighbour->dev = &loopback_dev;
+			dst->neighbour->dev = &per_net(loopback_dev, init_net());
 			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 19b1469..dbaf001 100644
--- a/net/decnet/dn_dev.c
+++ b/net/decnet/dn_dev.c
@@ -866,10 +866,10 @@ 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 == &per_net(loopback_dev, init_net()))
 			return rv;
 	}
-	dev = &loopback_dev;
+	dev = &per_net(loopback_dev, init_net());
 	dev_hold(dev);
 	goto last_chance;
 }
diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index 4263cd9..b553cd4 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -887,7 +887,7 @@ 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 = per_net(loopback_dev, init_net()).ifindex,
 			    .oif = oldflp->oif };
 	struct dn_route *rt = NULL;
 	struct net_device *dev_out = NULL;
@@ -904,7 +904,7 @@ 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, per_net(loopback_dev, init_net()).ifindex, oldflp->oif);
 
 	/* If we have an output interface, verify its a DECnet device */
 	if (oldflp->oif) {
@@ -955,7 +955,7 @@ source_ok:
 		err = -EADDRNOTAVAIL;
 		if (dev_out)
 			dev_put(dev_out);
-		dev_out = &loopback_dev;
+		dev_out = &per_net(loopback_dev, init_net());
 		dev_hold(dev_out);
 		if (!fl.fld_dst) {
 			fl.fld_dst =
@@ -964,7 +964,7 @@ source_ok:
 			if (!fl.fld_dst)
 				goto out;
 		}
-		fl.oif = loopback_dev.ifindex;
+		fl.oif = per_net(loopback_dev, init_net()).ifindex;
 		res.type = RTN_LOCAL;
 		goto make_route;
 	}
@@ -1010,7 +1010,7 @@ source_ok:
 					if (dev_out)
 						dev_put(dev_out);
 					if (dn_dev_islocal(neigh->dev, fl.fld_dst)) {
-						dev_out = &loopback_dev;
+						dev_out = &per_net(loopback_dev, init_net());
 						res.type = RTN_LOCAL;
 					} else {
 						dev_out = neigh->dev;
@@ -1031,7 +1031,7 @@ 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 = &per_net(loopback_dev, init_net());
 			dev_hold(dev_out);
 			res.type = RTN_LOCAL;
 			goto select_source;
@@ -1067,7 +1067,7 @@ select_source:
 			fl.fld_src = fl.fld_dst;
 		if (dev_out)
 			dev_put(dev_out);
-		dev_out = &loopback_dev;
+		dev_out = &per_net(loopback_dev, init_net());
 		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 a7d991d..201442c 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1056,7 +1056,7 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
 	ASSERT_RTNL();
 
 	if (!in_dev) {
-		if (event == NETDEV_REGISTER && dev == &loopback_dev) {
+		if (event == NETDEV_REGISTER && dev == &per_net(loopback_dev, init_net())) {
 			in_dev = inetdev_init(dev);
 			if (!in_dev)
 				panic("devinet: Failed to create loopback\n");
@@ -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 == &per_net(loopback_dev, init_net())) {
 			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 91b5729..ee77938 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -185,16 +185,18 @@ static int __init ic_open_devs(void)
 	struct ic_device *d, **last;
 	struct net_device *dev;
 	unsigned short oflags;
+	struct net_device *lo;
 
 	last = &ic_first_dev;
 	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);
+	lo = &per_net(loopback_dev, init_net());
+	if (dev_change_flags(lo, lo->flags | IFF_UP) < 0)
+		printk(KERN_ERR "IP-Config: Failed to open %s\n", lo->name);
 
 	for (dev = dev_base; dev; dev = dev->next) {
-		if (dev == &loopback_dev)
+		if (dev == lo)
 			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 3425752..2e1e41f 100644
--- a/net/ipv4/ipvs/ip_vs_core.c
+++ b/net/ipv4/ipvs/ip_vs_core.c
@@ -963,7 +963,7 @@ 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 == &per_net(loopback_dev, init_net()) || skb->sk)) {
 		IP_VS_DBG(12, "packet type=%d proto=%d daddr=%d.%d.%d.%d ign