Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Atheros SuperG bug fixes, as part of hunting down kern/174283.

The stageqdepth (global, over all staging queues) was being kept
incorrectly. It was being incremented whenever things were added,
but only decremented during a flush. During active fast frames activity
it wasn't being decremented, resulting in it always having a non-zero
value during normal fast-frames operation.

It was only used when checking if the aging queue should be checked;
we may as well just defer to each of those staging queue counters (which
look correct, thankfully.)

Whilst I'm here, add locking assertions in the staging queue add/remove
functions. The current crash shows that the staging queue has one frame,
but only has a tail pointer set (the head pointer being set to NULL.)
I'd like to grab a few more crashes where these locking assertions are
in place so I can narrow down the issue between "somehow locking is
messed up and things are racy" and "the stage queue head/tail pointer
manipulation logic is subtly wrong."

Tested:

* AR5416 STA, AR5413 AP; with FastFrames enabled in the AR5416 HAL.

PR: kern/174283

Don't panic if the stageq here is empty; just fall through with NULL
pointers and leave the stage queue flush routine to just do nothing
(since both head and tail here will be NULL.)

This should quieten the "stageq empty" panic where the stageq itself
is empty, but it won't fix the second KASSERT() here "staging queue empty"
as that's likely a different underlying problem.

PR: kern/174283

make superg/fast-frames state dynamically-allocated (and indirect off
the com structure instead of embedded); this reduces the overhead when
not configured and reduces visibility of the contents

Hoist 802.11 encapsulation up into net80211:
o call ieee80211_encap in ieee80211_start so frames passed down to drivers
are already encapsulated
o remove ieee80211_encap calls in drivers
o fixup wi so it recreates the 802.3 head it requires from the 802.11
header contents
o move fast-frame aggregation from ath to net80211 (conditional on
IEEE80211_SUPPORT_SUPERG):
- aggregation is now done in ieee80211_start; it is enabled when the
packets/sec exceeds ieee80211_ffppsmin (net.wlan.ffppsmin) and frames
are held on a staging queue according to ieee80211_ffagemax
(net.wlan.ffagemax) to wait for a frame to combine with
- drivers must call back to age/flush the staging queue (ath does this
on tx done, at swba, and on rx according to the state of the tx queues
and/or the contents of the staging queue)
- remove fast-frame-related data structures from ath
- add ieee80211_ff_node_init and ieee80211_ff_node_cleanup to handle
per-node fast-frames state (we reuse 11n tx ampdu state)
o change ieee80211_encap calling convention to include an explicit vap
so frames coming through a WDS vap are recognized w/o setting M_WDS

With these changes any device able to tx/rx 3Kbyte+ frames can use fast-frames.

Reviewed by: thompsa, rpaulo, avatar, imp, sephe

o move tdma+superg protocol defs out of public view
o add #ifdef _KERNEL to superg+tdma include files so they can be used
by user code to get the protocol defs

Fix enough bits so that fast frames work again:
o include ath ie in beacon frames
o fix probe response check for including ath ie
o add ieee80211_add_athcap shorthand for ap-side ie additions

split Atheros SuperG support out into it's own file that's included only
with a new IEEE80211_SUPPORT_SUPERG option