No beacons generated when you bring ath9k AP interface down and up.

[Ben Greear <greearb@candelatech.com>]

Been a long day, but I think I finally see the problem.

If you have an ath9k AP interface running with hostapd, and you
run:  ip link set vap0 down; ip link set vap0 up;
then it will disable beaconing.

One reason is that the ieee80211_do_open calls the
  ieee80211_bss_info_change_notify before it sets the RUNNING
flag, so it would disable beaconing.  A second is that
it doesn't set the BEACON_CHANGED flag anyway, so even if you
hack things to set RUNNING first, it still doesn't work right.

I'm not sure where the problem actually lies:  Should ath9k
start beaconing automatically on VAP interface add?  Is
it up to hostapd to detect the ifdown/ifup and re-set everything
up properly?  Or maybe it's just a very bad idea to bounce
a VAP interface with 'ip link set'?

Thanks,
Ben

--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com