[NET]: Make the loopback device per network namespace.

This patch makes loopback_dev per network namespace.  Adding
code to create a different loopback device for each network
namespace and adding the code to free a loopback device
when a network namespace exits.

This patch modifies all users the loopback_dev so they
access it as init_net.loopback_dev, 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.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 21 insertions, 5 deletions

diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index f3018bb7570d..0f9d8c60c964 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;
@@ -252,7 +253,7 @@ static void loopback_setup(struct net_device *dev)
 }
 
 /* Setup and register the loopback device. */
-static int __init loopback_init(void)
+static int loopback_net_init(struct net *net)
 {
         struct net_device *dev;
         int err;
@@ -262,12 +263,13 @@ static int __init loopback_init(void)
         if (!dev)
                 goto out;
 
+        dev->nd_net = net;
         err = register_netdev(dev);
         if (err)
                 goto out_free_netdev;
 
         err = 0;
-        loopback_dev = dev;
+        net->loopback_dev = dev;
 
 out:
         if (err)
@@ -279,7 +281,21 @@ out_free_netdev:
         goto out;
 }
 
-fs_initcall(loopback_init);
+static void loopback_net_exit(struct net *net)
+{
+        struct net_device *dev = net->loopback_dev;
+
+        unregister_netdev(dev);
+}
+
+static struct pernet_operations loopback_net_ops = {
+       .init = loopback_net_init,
+       .exit = loopback_net_exit,
+};
+
+static int __init loopback_init(void)
+{
+        return register_pernet_device(&loopback_net_ops);
+}
 
-struct net_device *loopback_dev;
-EXPORT_SYMBOL(loopback_dev);
+fs_initcall(loopback_init);