Merge branch 'ndo_ioctl-rework'

Arnd Bergmann says:

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ndo_ioctl rework

This series is a follow-up to the series for removing
compat_alloc_user_space() and copy_in_user() that has now
been merged.

I wanted to be sure I address all the ways that 'struct ifreq' is used
in device drivers through .ndo_do_ioctl, originally to prove that
my approach of changing the struct definition was correct, but then
I discarded that approach and went on anyway.

Roughly, the contents here are:

 - split out all the users of SIOCDEVPRIVATE ioctls into a
   separate ndo_siocdevprivate callback, to better see what
   gets used where

 - fix compat handling for those drivers that pass data
   directly inside of 'ifreq' rather than using an indirect
   ifr_data pointer

 - remove unreachable code in ndo_ioctl handlers that relies
   on command codes we never pass into that, in particular
   for wireless drivers

 - split out the ethernet specific ioctls into yet another
   ndo_eth_ioctl callback, as these are by far the most
   common use of ndo_do_ioctl today. I considered splitting
   them further into MII and timestamp controls, but
   went with the simpler change for now.

 - split out bonding and wandev ioctls into separate helpers

 - rework the bridge handling with a separate callback

At this point, only a few oddball things remain in ndo_do_ioctl:
appletalk and ieee802154 pass down SIOCSIFADDR/SIOCGIFADDR and
some wireless drivers have completely dead code.

I have thoroughly compile tested this on randconfig builds,
but not done any notable runtime testing, so please review.
All of it is also available as part of a larger branch at

https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git \
	compat-alloc-user-space-12

Changes since v2:
- rebase to net-next
- fix qeth regression
- Cc driver maintainers for each patch and in cover letter

Changes since v1:

- rebase to linux-5.14-rc2
- add conversion for ndo_siowandev, bridge and bonding drivers
- leave broken wifi drivers untouched for now

Link: https://lore.kernel.org/netdev/20201106221743.3271965-14-arnd@kernel.org/
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