linux-kernel - Re: attempt to scan fails (device busy) if essid/ssid was changed recently

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Date:	Tue, 07 Apr 2009 16:51:50 +0300
From:	Maxim Levitsky <maximlevitsky@...il.com>
To:	Johannes Berg <johannes@...solutions.net>
Cc:	linux-wireless <linux-wireless@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: attempt to scan fails (device busy) if essid/ssid was changed
 recently

On Tue, 2009-04-07 at 15:27 +0200, Johannes Berg wrote:
> On Tue, 2009-04-07 at 16:20 +0300, Maxim Levitsky wrote:
> 
> > > Of course, we can go back to dropping the scan request, but that
> > > wouldn't be very nice.
> > > 
> > > Is this creating any problems?
> 
> > Yep, but dropping the request won't help ether.
> 
> Indeed.
> 
> > Problem is that wpa_supplicant will attempt to scan before association,
> > scan fails (it doesn't know it is already running) thus it waits 10
> > seconds. (I patched it to wait 2 seconds).
> > 
> > It happens if user first disconnects, and then reconnects to a network
> > (typical test I do for time it takes to connect)
> > 
> > Now I patched it not to clear essid on disconnect, and this helped
> > reduce connect times by about 2 seconds.
> > 
> > now it takes just 3~4 seconds to connect to open network, and ~6 seconds
> > to WPA2 network.
> > 
> > (This is with patched dhclient, I reduced its timeouts, but this is
> > another story.... it seems that first DHCPREQUEST never succeeds, and I
> > tested this with 2 cards, and few wireless networks)
> 
> Have you tried with a new tree and wpa_supplicant's (from git) nl80211
> driver? Might be a lot better.
I use NM and wpa_supplicant from -git
Last time, I tried nl80211 wpa_supplicant driver it didn't work well,
but I try again soon I  hope.
 

Best regards,
	Maxim Levitsky
> 
> johannes

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