Merge branch 'skb_ext-fixes'

Paolo Abeni says:

====================
net: skb extension follow-ups

This series includes some follow-up for the recently added skb extension.
The first patch addresses an unlikely race while adding skb extensions,
and the following two are just minor code clean-up.

v1 -> v2:
 - be sure to flag the newly added extension as active in skb_ext_add()
====================

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