I using an Edimax EW-7318USG USB WIFI stick with a Centos 5.3 machine, using the rt73usb driver shipped with Centos/RHEL kernel.
Things work fine until I shut down wlan0 or reboot. ifdown wlan0 hangs. If I have wpa_supplicant running, I get a kernel panic when I reboot or stop wpa_supplicant (see below). - WPA works fine, otherwise.
I'm using wpa_supplicant with -Dwext. Is that OK?
There is one error msg while starting it
# service wpa_supplicant start
Starting wpa_supplicant: /etc/wpa_supplicant/wpa_supplicant.conf -iwlan0
-Dwext Device wlan0 kernel driver name: rt73usb.
ioctl[SIOCSIWAUTH]: Operation not supported
WEXT auth param 4 value 0x0 - [ OK ]
The modules loaded are
$ lsmod|grep -i rt
rt73usb 28609 0
crc_itu_t 6337 1 rt73usb
rt2x00usb 16577 1 rt73usb
rt2x00lib 25409 2 rt73usb,rt2x00usb
mac80211 137801 2 rt2x00usb,rt2x00lib
cfg80211 30793 2 rt2x00lib,mac80211
The text from the kernel panic is (typed by hand)
Process wpa_supplicant (...)
<0>Kernel panic - not syncing: Fatal exception
This happens at the end of shutdown, I could still see 'shutting down kernel logger'.
I already blacklisted the rt2500usb driver which was originally loaded in addition to rt73usb, but that didn't help.
Can you see anything I'm doing wrong?
Is wpa_supplicant OK to use with rt73usb?
Any idea what's going wrong?
The problem isn't wpa_supplicant. From the (incomplete) backtrace I think the bug is in mac80211.
I recommend creating a bug report on the Centos bugtracker.