return the devices dummyX to the initial network namespace after container closure.

index bab0158..efa990c 100644
@@ -160,6 +160,41 @@ static struct rtnl_link_ops dummy_link_ops __read_mostly = {
 module_param(numdummies, int, 0);
 MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices");
 
+
+static void __net_exit dummy_net_exit(struct net *net) {
+       struct net_device *dev, *aux;
+       int err;
+
+       if(net == &init_net) return;
+
+       rtnl_lock();
+       for_each_netdev_safe(net, dev, aux) {
+               if(dev->rtnl_link_ops == &dummy_link_ops) {
+                       err = dev_change_net_namespace(dev, &init_net, dev->name);
+                       if(err) {
+                               char fb_name[IFNAMSIZ];
+                               printk (KERN_INFO "%s: dev_change_net_namespace(init_net,%s) err: %d\n",
+                                       __func__,dev->name,err);
+                               snprintf(fb_name, IFNAMSIZ, "dev%d", dev->ifindex);
+                               err = dev_change_net_namespace(dev, &init_net, dev->name);
+                               if(err)
+                                       printk (KERN_INFO "%s: dev_change_net_namespace(%s,init_net,%s) err: %d\n",
+                                               __func__,dev->name,fb_name,err);
+                               else
+                                       printk (KERN_INFO "%s: %s rename to %s\n",
+                                               __func__,dev->name,fb_name);
+
+                       }
+               }
+       }
+       rtnl_unlock();
+}
+
+static struct pernet_operations __net_initdata dummy_net_ops = {
+       .exit = dummy_net_exit,
+};
+
+
 static int __init dummy_init_one(void)
 {
        struct net_device *dev_dummy;

@@ -184,6 +219,10 @@ static int __init dummy_init_module(void)
 {
        int i, err = 0;
 
+       err = register_pernet_device(&dummy_net_ops);
+       if(err)
+               return err;
+
        rtnl_lock();
        err = __rtnl_link_register(&dummy_link_ops);
 

@@ -191,8 +230,10 @@ static int __init dummy_init_module(void)
                err = dummy_init_one();
                cond_resched();
        }
-       if (err < 0)
+       if (err < 0) {
                __rtnl_link_unregister(&dummy_link_ops);
+               unregister_pernet_device(&dummy_net_ops);
+       }
        rtnl_unlock();
 
        return err;

@@ -201,6 +242,7 @@ static int __init dummy_init_module(void)
 static void __exit dummy_cleanup_module(void)
 {
        rtnl_link_unregister(&dummy_link_ops);
+       unregister_pernet_device(&dummy_net_ops);
 }
 
 module_init(dummy_init_module);