Bug#408207: Madwifi problems associating using wext/NetworkManager

[Tim Hull]

I have spent a significant amount of time dealing with issues between
MadWifi and wext/wpasupplicant/NetworkManager on Debian (etch, lenny, AND
sid).  As it stands, there are still significant issues - in factI cannot
associate *at all* to my stock, unencrypted WRT54G using
NetworkManager+madwifi on my Atheros 5424 card (bundled with MacBook Core
Duo). This is about as standard of a configuration as you can get, so it's
obviously a widespread bug.

I have managed to isolate the issue to a degree.  Though I'm somewhat
C-impaired, the issue does seem to stem from issues w/wext compliance - and
in particular AP scanning and the "preempt_scan" function.  This seems to be
a long-standing issue, and has existed in every build of madwifi I've
tried.  The upstream bug mentioned earlier in this thread is still open, and
there appears to be no progress whatsoever on that front.

Anyway, there is currently two workarounds that I've tested and know to
work.  The first, and the one used by Ubuntu, is to change NetworkManager's
source such that the wpasupplicant's "madwifi" driver is used for cards
using madwifi instead of the generic "wext" driver.  This seems to work
well, though the Debian maintainer for NetworkManager didn't like the idea
of special behavior for madwifi.  Secondly, there is the option of totally
removing the preempt_scan() function and all calls to it from
ieee80211_wireless.c.  This seems to work perfectly to me, but may come at
the loss of some functionality (namely, wireless scan timeout).  This
function was only added in the last 6-9 months, though, so the driver is
known to work without it.

I've attached my patch to remove the function in question (preempt_scan)
from ieee80211.c. I've attached patches to both the release used in unstable
and the trunk from madwifi.org (which, in my experience, blows away the
release in wireless performance - in addition to adding support for the
Atheros 802.11n chipsets).

I hope a workaround such as the one(s) I've suggested can be uploaded to the
archive - this can be quite a nasty bug for some Atheros users...
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