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

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Message-Id: <1239110010.22453.41.camel@johannes.local>
Date:	Tue, 07 Apr 2009 15:13:30 +0200
From:	Johannes Berg <johannes@...solutions.net>
To:	Maxim Levitsky <maximlevitsky@...il.com>
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 16:04 +0300, Maxim Levitsky wrote:

> > > > > Looking a bit deeper I discovered that each time NM disconnects from a
> > > > > networks it sets random ssid/essid to the card (using wireless
> > > > > extensions)
> > > > 
> > > > This forces a scan
> > > > 
> > > > > After that scan fails for some time.
> > > > > 
> > > > > as a NM free example you can run 
> > > > > 
> > > > > iwconfig wlan0 essid dummy
> > > > > iwlist scan
> > > > 
> > > > and then this fails with EBUSY.
> > > Thanks for explanation.
> > > Since NM has its reasons to clear essid (to prevent unwanted
> > > association), then what can be  done to prevent this (and still use
> > > wireless extensions, since nl80211 support isn't yet mature)?
> > 
> > Nothing. Wext sucks, news at 11, yadda.
> Thanks.
> Everything understood.

Of course, we can go back to dropping the scan request, but that
wouldn't be very nice.

Is this creating any problems?

johannes

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