Merge branch 'netlink-validation-improvements-refactoring'

Johannes Berg says:

====================
netlink validation improvements/refactoring

Alright, this is the resend now, really just changing

 - the WARN_ON_ONCE() as spotted by Jakub;
 - mark the export patch no longer RFC.
   I wasn't actually sure if you meant this one too, and I really
   should dig out and polish the code that showed it in userspace.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>