ap_vlan_open exits hwsim tests

Jouni Malinen j
Wed Mar 12 02:31:09 PDT 2014

On Wed, Mar 12, 2014 at 10:58:46AM +0200, Jouni Malinen wrote:
> On Wed, Mar 12, 2014 at 12:43:33AM -0700, Jacob Minshall wrote:
> > I have found the offending commit
> > 
> > 89c86a64cd056e283323710c9ddf6f7090a450c8
> > kobject: delay kobject release for random time

> That said, this is test functionality and it does not look like one
> would enable CONFIG_DEBUG_KOBJECT_RELEASE=y for a production build.. I
> didn't actually have that enabled in my kernel which would explain why I
> don't see the issue. As a quick workaround, I'd assume you can just
> remove that from the kernel build used for hwsim tests for now. I'll see
> what happens when I do the opposite.. :)

It looks like this kernel debug options makes NL80211_CMD_DEL_INTERFACE
and SIOCGIFBR(BRCTL_DEL_BRIDGE) block for 1-8 seconds. ap_vlan_open ends
up having to run four of these operations during hostapd deinit path on
"REMOVE wlan3" control interface operation. Consequently, this is very
likely to hit the 10 second timeout.

IMHO, the kernel is misbehaving from user space view point, so blindly
increasing the timeout is not really desirable. That said, it would be
good to confirm that this kind of blocking behavior on interface removal
is indeed expected result of that kernel commit and if so, make it
possible to run the hwsim test cases even with this behavior in place.
wpaspy.py could be changed to accept a timeout value for the request()
command and the hostapd REMOVE commands could use larger timeout value
to workaround this.
Jouni Malinen                                            PGP id EFC895FA

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