[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/rtnetlink.c b/net/core/rtnetlink.c
index cec1111..8c971a2 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -539,13 +539,16 @@
 	int s_idx = cb->args[0];
 	struct net_device *dev;
 
-	for (dev=dev_base, idx=0; dev; dev = dev->next, idx++) {
+	idx = 0;
+	for_each_netdev(dev) {
 		if (idx < s_idx)
-			continue;
+			goto cont;
 		if (rtnl_fill_ifinfo(skb, dev, NULL, 0, RTM_NEWLINK,
 				     NETLINK_CB(cb->skb).pid,
 				     cb->nlh->nlmsg_seq, 0, NLM_F_MULTI) <= 0)
 			break;
+cont:
+		idx++;
 	}
 	cb->args[0] = idx;