Merge branch 'rhashtable-next'

Herbert Xu says:

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rhashtable: Fixes + cleanups + preparation for multiple rehash

Patch 1 fixes the walker so that it behaves properly even during
a resize.

Patch 2-3 are cleanups.

Patch 4-6 lays some ground work for the upcoming multiple rehashing.

This revision fixes the warning coming from the bucket_table->size
downsize and improves its changelog.
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Signed-off-by: David S. Miller <davem@davemloft.net>