Merge branch 'genetlink-support-per-command-policy-dump'

Jakub Kicinski says:

====================
genetlink: support per-command policy dump

The objective of this series is to dump ethtool policies
to be able to tell which flags are supported by the kernel.
Current release adds ETHTOOL_FLAG_STATS for dumping extra
stats, but because of strict checking we need to make sure
that the flag is actually supported before setting it in
a request.

Ethtool policies are per command, and so far only dumping
family policies was supported.

The series adds new set of "light" ops to genl families which
don't have all the callbacks, and won't have the policy.
Most of families are then moved to these ops. This gives
us 4096B in savings on an allyesconfig build (not counting
the growth that would have happened when policy is added):

     text       data       bss        dec       hex
244415581  227958581  78372980  550747142  20d3bc06
244415581  227962677  78372980  550751238  20d3cc06

Next 5 patches deal the dumping per-op policy.

v3:

The actually patch to dump per-op policy was taken out and
will come in a series from Johannes, to make sure uAPI is
consistent from the start.

For dump-specific policies I think it should be fine to add
a new pair of members to the "full" ops, and not overthink it.

v2:
 - remove the stale comment in taskstats
 - split patch 8 -> 8, 9
 - now the getfamily policy is also in the op
 - make cmd u32
v1:
 - replace remaining uses of "light" with "small"
 - fix dump (ops can't be on the stack there)
 - coding changes in patch 4
 - new patch 7
 - don't echo op in responses - to make dump all easier

Dave - this series will cause a very trivial conflict with
the patch I sent to net. Both sides add some kdoc to struct
genl_ops so we'll need to keep it all.  I'm sending this
already because I also need to restructure ethool policies
in time for 5.10 if we want to use it for the stats flag.
====================

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