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

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Date:	Tue, 07 Apr 2009 10:18:16 +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 03:00 +0300, Maxim Levitsky wrote:

> I noticed that always first attempt at scan fails when NM asks for scan.
> I also noticed that this happens with quite recent kernels (I think
> 2,6.28) didn't have this behavior.

I'm pretty sure it did.

> 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.

johannes

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