- s/cant/can't/

(cherry picked from commit 026520a5f2d2ec01e19494c37b87448df86ef21a)

This reverts commit b65f813c1ab99448278961c5ca80dc422b1eae29.
As a side effect this also seems to fix wtap which seems to have
lost the epoch over the input path in between.

Sponsored by:	The FreeBSD Foundation

(cherry picked from commit 1c6dd33d26eb02c6145383a49150965eeca61120)

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with:		pfg
MFC After:		3 days
Sponsored by:		Netflix

For TSF and beacon generation, each STA has to start its local TSF timer
and sends beacon frames when it reaches the state IEEE80211_S_RUN.
The TSF timer will be used for IBSS merge and beacon frame transmission.

The TSF timer is kept in the HAL of wtap(4). It is working by
continuously updating its value on timer interrupt simulated
by callout_reset().

When receiving beacons, the STA will be merged into the IBSS if
- the STA has the same SSID as the beacon sender
- the STA's TSF timer is smaller than the beacon sender's TSF timer.

After the merging process, the younger STA will be in the IBSS
created by the older STA and the younger STA stops sending beacon
frames.  So beacon frames will always be sent by the oldest STA
in IBSS.

Sponsored by:	Google, Inc. (GSoC 2022)
Reviewed By:	lwhsu, adrian
Differential Revision: https://reviews.freebsd.org/D35841

Originally, wtap_node_write() gets the wrong softc by iterating V_inet and
gets the ifp by string comparison, then gets softc by ifp->if_softc.
However, ifp->if_softc will not point to the correct softc owned by
ieee80211com, and thus causes a kernel panic.
Fix it by assigning softc to cdev's si_drv1 in wtap_vap_create()
and get the softc directly via dev->si_drv1 in wtap_node_write().

The cdev created by wtap_vap_create() use the name of ieee80211com
rather than the vap's name. It will cause the second vap based on
the same ieee80211com as first vap fail to create a device node
because the device node is already exists. Fix it by assigning
vap->iv_ifp->if_xname to cdev's name.

Sponsored by:	Google, Inc. (GSoC 2022)
Reviewed by:	adrian, cy, bz
Differential Revision: https://reviews.freebsd.org/D35752

The original interface created by wtap is named "wlan%d", which is the
same as the name of the vap created by wlan(4) and cause ifconfig(8)
may output like this:

    wlan0:
            parent interface: wlan0

Rename the interface created by wtap(4) to "wtap%d" to avoid confusing.

Reviewed by:	adrian
Sponsored by:	Google, Inc. (GSoC 2022)
Differential Revision:	https://reviews.freebsd.org/D35751

- Remove the variable set but not used to fix build on -CURRENT
- Remove bzero() on the space malloc'd with M_ZERO flag.

Signed-off-by:  En-Wei Wu <enweiwu@FreeBSD.org>

Sponsored by:	Google, Inc. (GSoC 2022)
Differential Revision:	https://reviews.freebsd.org/D35624

In r178354 with the introduction of multi-bss ("vap") support factoring
out started and with r193340 ieee80211_media_change() no longer returned
ENETRESET but only 0 or error.
As ieee80211(9) tells the ieee80211_media_change() function should not
be called directly but is registered with ieee80211_vap_attach() instead.

Some drivers have not been fully converted.  After fixing the return
checking some of these functions were simply wrappers between
ieee80211_vap_attach() and ieee80211_media_change(), so remove the extra
function, where possible as well.

PR:		248955
Submitted by:	Tong Zhang (ztong0001 gmail.com) (original)
MFC after:	3 days
Sponsored by:	The FreeBSD Foundation