Return-path: Received: from mail-wg0-f52.google.com ([74.125.82.52]:57158 "EHLO mail-wg0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752046AbaEVN7H convert rfc822-to-8bit (ORCPT ); Thu, 22 May 2014 09:59:07 -0400 Received: by mail-wg0-f52.google.com with SMTP id l18so3403474wgh.23 for ; Thu, 22 May 2014 06:59:05 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1400766356.4174.14.camel@jlt4.sipsolutions.net> References: <1400765294-14732-1-git-send-email-michal.kazior@tieto.com> <1400765294-14732-3-git-send-email-michal.kazior@tieto.com> <1400766356.4174.14.camel@jlt4.sipsolutions.net> Date: Thu, 22 May 2014 15:59:05 +0200 Message-ID: (sfid-20140522_155911_533028_787A7273) Subject: Re: [PATCH 2/3] mac80211: use csa counter offsets instead of csa_active From: Michal Kazior To: Johannes Berg Cc: linux-wireless Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 22 May 2014 15:45, Johannes Berg wrote: > On Thu, 2014-05-22 at 15:28 +0200, Michal Kazior wrote: >> vif->csa_active is protected by mutexes only. This >> means it is unreliable to depend on it on codeflow >> in non-sleepable beacon and CSA code. There was no >> guarantee to have vif->csa_active update be >> visible before beacons are updated on SMP systems. >> >> Using csa counter offsets which are embedded in >> beacon struct (and thus are protected with single >> RCU assignment) is much safer. > > This seems reasonable, but many uses of csa_active remain, no? hwsim for > example seems to access it without locking as well. Since the problem could be split I went with fixing things step-by-step. I was trying to tackle csa_active issue as well but I'm yet to arrive at a satisfactory solution. It's probably best to kill it and introduce a drv_switch_beacon_done(). With my patchset csa_active isn't as critical for decision making in the code. Michał