ifdown wlan0 hangs indefinatley

i haven't had much success with rebooting cleanly or taking down the
wlan0 interface.
is this supported?

tailing ksyms says

<4>sending authentication1 request, awaiting response
<5>tx: got desc 4, 12 remain
<4>attempt to set the timer when the card interface is not up!

but ifdown never returns.

what to check?