Merge branch 'ipv6-cleanups'

Cong Wang says:

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ipv6: clean up locking code in anycast and mcast

This patchset cleans up the locking code in anycast.c and mcast.c
and makes the refcount code more readable.

Signed-off-by: Cong Wang <[email protected]>
v1 -> v2:
* refactor some code and make it in a separated patch
* update comments
====================

Signed-off-by: David S. Miller <[email protected]>