[PATCH 03/11] wpa_s: use sched_scan in driver init

Bondar, Alexander alexander.bondar at intel.com
Sun Oct 16 04:24:44 EDT 2011


> Hi Alex,
> 
> On Wed, 2011-10-05 at 12:38 +0200, Bondar, Alexander wrote:
> > > diff --git a/wpa_supplicant/sme.c b/wpa_supplicant/sme.c index
> > > dbf385e..4cb5062 100644
> > > --- a/wpa_supplicant/sme.c
> > > +++ b/wpa_supplicant/sme.c
> > > @@ -237,6 +237,7 @@ void sme_authenticate(struct wpa_supplicant
> *wpa_s,
> > >  	}
> > >  #endif /* CONFIG_P2P */
> > >
> > > +	wpa_supplicant_cancel_sched_scan(wpa_s);
> > >  	wpa_supplicant_cancel_scan(wpa_s);
> >
> > Don't you need to wait for EVENT_SCHED_SCAN_STOPPED before
> proceeding
> > with authentication flow? There may be race condition when
> authentication request is set to the driver while sched_scan is still in
> progress.
> 
> I don't see a problem with that.  Nothing prevents the driver and the
> firmware from supporting authentication while a sched_scan is running (in
> theory).  If it cannot be done, the lower driver/hardware can always send a
> sched_scan stopped event before continuing with authentication (like the
> wl12xx driver does by checking the mac80211 idle flag).
> 
> And furthermore, here it's the same thing as with normal scan.  We don't
> want to keep scanning after we found what we want, so we call
> cancel_scan().  But we don't really care if the scan keeps running during
> authentication.

I see. Also from my discussion with Johannes I understood that we can assume canceling scheduled scan as synchronous flow.
When it returns we can consider scheduled scan is stopped.
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