From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from xc.sipsolutions.net ([83.246.72.84]:48866 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752063AbZDGNAF (ORCPT ); Tue, 7 Apr 2009 09:00:05 -0400 Subject: Re: attempt to scan fails (device busy) if essid/ssid was changed recently From: Johannes Berg To: Maxim Levitsky Cc: linux-wireless , linux-kernel In-Reply-To: <1239108689.15015.3.camel@maxim-laptop> (sfid-20090407_145137_740898_8D0C40FD) 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) Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-FXUH2CrM6OWQI2KTx2n2" Date: Tue, 07 Apr 2009 14:56:41 +0200 Message-Id: <1239109001.22453.40.camel@johannes.local> (sfid-20090407_150009_750581_7626B1EC) Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: --=-FXUH2CrM6OWQI2KTx2n2 Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Tue, 2009-04-07 at 15:51 +0300, Maxim Levitsky wrote: > > > I noticed that always first attempt at scan fails when NM asks for sc= an. > > > I also noticed that this happens with quite recent kernels (I think > > > 2,6.28) didn't have this behavior. > >=20 > > I'm pretty sure it did. > I am sure that on older kernel there was no -EBUSY error returned to > userspace. It probably just stalled the client. Can't imagine it did, maybe it just dropped the request though without indicating an error. > > > 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) > >=20 > > This forces a scan > >=20 > > > After that scan fails for some time. > > >=20 > > > as a NM free example you can run=20 > > >=20 > > > iwconfig wlan0 essid dummy > > > iwlist scan > >=20 > > 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. johannes --=-FXUH2CrM6OWQI2KTx2n2 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Comment: Johannes Berg (powerbook) iQIcBAABAgAGBQJJ202HAAoJEKVg1VMiehFYa1wP/2N4Qs2BTqNir8AoSn4OA01U HuoW4JzCTvOB5H3fawtYBoKaCQQCoo3fHvsakZh8qJsdYdopKb4uRyl89l264JFY 1ckkUGNxrZevt+oKMYAVyy4xasQU+JxG2zx6T3RtBKCyNH3S3s3aouQUW2ghDvCL M7LqeJia+ZgSM26DcVMRzgKAi2W0I0LfuA+4DBt5ElN+0K8R1IFoAJ4y42u8qcr3 Dpc2QU/ytH0G3uE/KM57BuBIIkuc66L0InAxfof5HwddhLOuapeXceP7MY3+xdFL x+9vAQjNB5fcch0qYGOAYVJcjXCkjKXr3jXEMlIKY97gDletmlWwT1hcerFNJTRK VfaNuMCqpPAYcSvQbIUqeZxy4z+127Fv0mZhCmSrsujs2XOby5U4CWzmPfQaNlV5 tU/FZWOHk3dQANLPnrdkzLiS2a8ktmvJiLMeyhTSRqY9tXhkOEF9su2rTVkvxSOA +Jg2tVAAJUSztIcWRDgXWJCDa1B+UG5uIe84AGPVTmxdCUvDoEe09E1n2r4mVr9p 5zkneU5aXJwRDXHuMuqf4zkvRfMZj+QQVcu5qaD8QyanzZ/aTaLy0lTki2GYD6CG L0FgyOwmsQO5u1Wlu07vvmMtDOVMIUXDSyWg9/RTU6AQlFE6lPSYo9sidQ8h3sBK jQSv2CLTotcmWrxE2c9A =co6y -----END PGP SIGNATURE----- --=-FXUH2CrM6OWQI2KTx2n2--