Re: [PATCH 5/5] mac80211: fix issuing idle calls when device open count is 0

[Johannes Berg <johannes@sipsolutions.net>]

On Tue, 2010-12-07 at 09:28 -0800, Paul Stewart wrote:

> > Actually I believe it happens _during_ ifdown, but when the running bit
> > is already cleared, so I guess this is about right -- although it
> > shouldn't matter since the recalc_idle in do_stop should catch it later.
> 
> So the scenario is as follows.  If you down an interface
> ieee80211_do_stop() first decrements local->open_count, then later
> calls __ieee80211_recalc_idle, et al.  This means that later in this
> call graph if ieee80211_hw_config() finally gets called, open_count is
> already 0 and therefore drv_config is never called.  Luis' reference
> to scan_completed() above is probable in reference to older versions
> of compat where ieee80211_stop() called ieee80211_scan_cancel()
> directly.  My admittedly casual look at wireless-testing seems to
> imply that path may not exist in current compat, although my tests
> seem to indicate the same class of problem still exists.

Yeah I can see how a problem like this happens -- but I think the change
in scan_finished() is pointless because it'll be handled during
do_stop() anyway.

johannes