ipv4: ip_ptr cleanups

dev->ip_ptr is protected by rtnl and rcu.

Yet some places dont use appropriate primitives and/or locking rules.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 4935b84..b8cf282 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -362,7 +362,7 @@
 	if (sdata->vif.type != NL80211_IFTYPE_STATION)
 		return NOTIFY_DONE;
 
-	idev = sdata->dev->ip_ptr;
+	idev = __in_dev_get_rtnl(sdata->dev);
 	if (!idev)
 		return NOTIFY_DONE;