[NET]: Rework dev_base via list_head (v3)

Cleanup of dev_base list use, with the aim to simplify making device
list per-namespace. In almost every occasion, use of dev_base variable
and dev->next pointer could be easily replaced by for_each_netdev
loop. A few most complicated places were converted to using
first_netdev()/next_netdev().

Signed-off-by: Pavel Emelianov <xemul@openvz.org>
Acked-by: Kirill Korotaev <dev@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev_mcast.c b/net/core/dev_mcast.c
index 7d57bf7..5a54053 100644
--- a/net/core/dev_mcast.c
+++ b/net/core/dev_mcast.c
@@ -223,7 +223,7 @@
 	loff_t off = 0;
 
 	read_lock(&dev_base_lock);
-	for (dev = dev_base; dev; dev = dev->next) {
+	for_each_netdev(dev) {
 		if (off++ == *pos)
 			return dev;
 	}
@@ -232,9 +232,8 @@
 
 static void *dev_mc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
-	struct net_device *dev = v;
 	++*pos;
-	return dev->next;
+	return next_net_device((struct net_device *)v);
 }
 
 static void dev_mc_seq_stop(struct seq_file *seq, void *v)