Merge branch 'mptcp-Optimize-received-options-handling'

Mat Martineau says:

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mptcp: Optimize received options handling

These patches optimize received MPTCP option handling in terms of both
storage and fewer conditionals to evaluate in common cases, and also add
a couple of cleanup patches.

Patches 1 and 5 do some cleanup in checksum option parsing and
clarification of lock handling.

Patches 2 and 3 rearrange struct mptcp_options_received to shrink it
slightly and consolidate frequently used fields in the same cache line.

Patch 4 optimizes incoming MPTCP option parsing to skip many extra
comparisons in the common case where only a DSS option is present.
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Signed-off-by: David S. Miller <davem@davemloft.net>