Association never expires after ejecting a PS-mode client card

[John Zhuge]

On a laptop, a PCMCIA client card attaches to a HostAP-based AP.
Set the client to PS-mode.
And then eject the PCMCIA wireless card.

Normally the association should expire in 5 minutes, i.e., the
"/proc/net/hostap/wlan0/<MAC>" file disappears.
But in this case, the association never expires.

Has anyone seen this problem?
Thanks.

-- 
John Zhuge