netns 2/2: extract net_create()

net_create() will be used by C/R to create fresh netns on restart.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/net_namespace.c

@@ -115,38 +115,34 @@ static void net_free(struct net *net)
 	kmem_cache_free(net_cachep, net);
 }
 
-struct net *copy_net_ns(unsigned long flags, struct net *old_net)
+static struct net *net_create(void)
 {
-	struct net *new_net = NULL;
-	int err;
-
-	if (!(flags & CLONE_NEWNET))
-		return get_net(old_net);
-
-	err = -ENOMEM;
-	new_net = net_alloc();
-	if (!new_net)
-		goto out_err;
+	struct net *net;
+	int rv;
 
+	net = net_alloc();
+	if (!net)
+		return ERR_PTR(-ENOMEM);
 	mutex_lock(&net_mutex);
-	err = setup_net(new_net);
-	if (!err) {
+	rv = setup_net(net);
+	if (rv == 0) {
 		rtnl_lock();
-		list_add_tail(&new_net->list, &net_namespace_list);
+		list_add_tail(&net->list, &net_namespace_list);
 		rtnl_unlock();
 	}
 	mutex_unlock(&net_mutex);
+	if (rv < 0) {
+		net_free(net);
+		return ERR_PTR(rv);
+	}
+	return net;
+}
 
-	if (err)
-		goto out_free;
-out:
-	return new_net;
-
-out_free:
-	net_free(new_net);
-out_err:
-	new_net = ERR_PTR(err);
-	goto out;
+struct net *copy_net_ns(unsigned long flags, struct net *old_net)
+{
+	if (!(flags & CLONE_NEWNET))
+		return get_net(old_net);
+	return net_create();
 }
 
 static void cleanup_net(struct work_struct *work)