Merge branch 'ipv6-fib6_ref-conversion-to-refcount_t'

Eric Dumazet says:

====================
ipv6: fib6_ref conversion to refcount_t

We are chasing use-after-free in IPv6 that could have their origin
in fib6_ref 0 -> 1 transitions.

This patch series should help finding the root causes if these
illegal transitions ever happen.
====================

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