[PATCH] don't continually reschedule specific scans

Dan Williams dcbw at redhat.com
Mon Jun 2 15:23:09 EDT 2008


On Mon, 2008-06-02 at 15:20 -0400, Dan Williams wrote:
> On Mon, 2008-06-02 at 15:01 -0400, Pavel Polischouk wrote:
> > Dan Williams wrote:
> > > In situations where the driver does background scanning and sends a
> > > steady stream of scan results, wpa_supplicant would continually
> > > reschedule the scan.  This resulted in specific SSID scans never
> > > happening for a hidden AP, and the supplicant never connecting to the AP
> > > because it never got found.  Instead, if there's an already scheduled
> > > scan, and a request comes in to reschedule it, and there are enabled
> > > scan_ssid=1 network blocks, let the scan happen anyway so the hidden
> > > SSID has a chance to be found.
> > >   
> > Tested the patch as a possible way to fix "failure scenario 1" of this 
> > bug: https://bugzilla.redhat.com/show_bug.cgi?id=449215
> > The situation does improve - it is more often able to break the scanning 
> > deadlock, associate and proceed to authentication stage.
> 
> You'll need to pair this patch with the ipw2200 patch I just re-posted
> for ipw2200 direct scan queuing (attached so you don't have to find it).
> The combination makes ipw2200 + wpa_supplicant a lot happier with hidden
> SSIDs.

I haven't tested the patch out for poor link quality like you mention in
the bug report, but it certainly can't hurt and should probably help
keep the AP in the supplicant's scan list, which would help the
re-connection.

Dan

> Dan
> 
> > However, it doesn't work every time. Sometimes the scanning still times 
> > out. I do see the following lines in the log (generated with single -d):
> > 
> > ---------------------------------
> > No suitable AP found.
> > Not rescheduling scan to ensure that specific SSID scans occur
> > Starting AP scan (specific SSID)
> > ...
> > ------------------------------------
> > 
> > However, subsequent arriving lists of available APs still list my AP as 
> > <hidden>. Is it possible the driver somehow ignores the scan request for 
> > a specific AP? Or supplicant somehow loses the correct scan lists?  The 
> > driver is ipw2200.
> > 
> > Also, I sometimes see in the log file that wpa_supplicant attempts to 
> > associate with AP 00:00:00:00:00:00, thinking it matches my ESSID.
> > 
> > Pavel
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