[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/ipv6/mcast.c b/net/ipv6/mcast.c
index 6c27589..3e308fb 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -2331,9 +2331,8 @@
 	struct ifmcaddr6 *im = NULL;
 	struct igmp6_mc_iter_state *state = igmp6_mc_seq_private(seq);
 
-	for (state->dev = dev_base, state->idev = NULL;
-	     state->dev;
-	     state->dev = state->dev->next) {
+	state->idev = NULL;
+	for_each_netdev(state->dev) {
 		struct inet6_dev *idev;
 		idev = in6_dev_get(state->dev);
 		if (!idev)
@@ -2360,7 +2359,7 @@
 			read_unlock_bh(&state->idev->lock);
 			in6_dev_put(state->idev);
 		}
-		state->dev = state->dev->next;
+		state->dev = next_net_device(state->dev);
 		if (!state->dev) {
 			state->idev = NULL;
 			break;
@@ -2475,9 +2474,9 @@
 	struct ifmcaddr6 *im = NULL;
 	struct igmp6_mcf_iter_state *state = igmp6_mcf_seq_private(seq);
 
-	for (state->dev = dev_base, state->idev = NULL, state->im = NULL;
-	     state->dev;
-	     state->dev = state->dev->next) {
+	state->idev = NULL;
+	state->im = NULL;
+	for_each_netdev(state->dev) {
 		struct inet6_dev *idev;
 		idev = in6_dev_get(state->dev);
 		if (unlikely(idev == NULL))
@@ -2513,7 +2512,7 @@
 				read_unlock_bh(&state->idev->lock);
 				in6_dev_put(state->idev);
 			}
-			state->dev = state->dev->next;
+			state->dev = next_net_device(state->dev);
 			if (!state->dev) {
 				state->idev = NULL;
 				goto out;