Return-path: Received: from s3.sipsolutions.net ([5.9.151.49]:48195 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751553AbbCKQUZ (ORCPT ); Wed, 11 Mar 2015 12:20:25 -0400 Message-ID: <1426090817.1904.6.camel@sipsolutions.net> (sfid-20150311_172029_378469_1E4F30A0) Subject: Re: Connection issues with BW Tracking in mac80211 From: Johannes Berg To: Krishna Chaitanya Cc: linux-wireless Date: Wed, 11 Mar 2015 17:20:17 +0100 In-Reply-To: (sfid-20150311_171529_797404_ECB8E5E9) References: <1424772587.2192.14.camel@sipsolutions.net> <1424774105.2192.29.camel@sipsolutions.net> <1424810867.2192.60.camel@sipsolutions.net> <1424851368.2050.8.camel@sipsolutions.net> (sfid-20150311_171529_797404_ECB8E5E9) Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Wed, 2015-03-11 at 21:45 +0530, Krishna Chaitanya wrote: > I did some experiments on this and found the root cause. > > We are using 5GHz in WORLD Mode, so only passive scan is allowed. > So when connecting the very first time, the mac80211 MLME sees that > there are no probe_resp ies (only beacon_ies are present) and it sends > a directed probe and updates the probe_resp ies. (and also the "ies"). > > But when config is changed and we get disconnected, beacon_ies are updated > with the new config, but the probe_resp ies are not. > cfg80211_bss_update assigns > probe_resp ies to "ies' and mac80211 updates its bss info based on the > probe_resp > ies which have old config causing the issue. > > Solution: > > 1) Make the directed probe mandatory. > 2) As you suggested maintain timestamps for probe_resp_ies and beacon_ies > and use the latest. > > Any takes? What's the operational problem here? I don't really see it. Are you afraid users will reconfigure their APs often enough for this to be an issue? johannes