From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755940AbZDGNUd (ORCPT ); Tue, 7 Apr 2009 09:20:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751799AbZDGNUV (ORCPT ); Tue, 7 Apr 2009 09:20:21 -0400 Received: from mail-qy0-f118.google.com ([209.85.221.118]:46081 "EHLO mail-qy0-f118.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751663AbZDGNUT (ORCPT ); Tue, 7 Apr 2009 09:20:19 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=LYaSgibHP5DxbYQPLqd+9T4OL0Rq/m7N0q7Cm3gUo06ItyTaATRa/u0vVKV8lUOb+N xVQhI+iElpuL8oeuj0Pu/9Z7vbg4+9i6j8qqB7mQctQxoWdY5haNrc0dxc7mzhy0N+GF ra62ok6zRPy0i9sk8DV1L3tkEgqVEPL8nNtw8= Subject: Re: attempt to scan fails (device busy) if essid/ssid was changed recently From: Maxim Levitsky To: Johannes Berg Cc: linux-wireless , linux-kernel In-Reply-To: <1239110010.22453.41.camel@johannes.local> References: <1239062401.4705.23.camel@maxim-laptop> (sfid-20090407_020013_939126_90578556) <1239092296.22453.1.camel@johannes.local> <1239108689.15015.3.camel@maxim-laptop> (sfid-20090407_145137_740898_8D0C40FD) <1239109001.22453.40.camel@johannes.local> <1239109497.15015.12.camel@maxim-laptop> (sfid-20090407_150534_375314_4DA28551) <1239110010.22453.41.camel@johannes.local> Content-Type: text/plain Date: Tue, 07 Apr 2009 16:20:12 +0300 Message-Id: <1239110412.15015.23.camel@maxim-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.24.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2009-04-07 at 15:13 +0200, Johannes Berg wrote: > 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? Yep, but dropping the request won't help ether. 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) Best regards, Maxim Levitsky > > johannes