Return-path: Received: from mail-oa0-f41.google.com ([209.85.219.41]:61576 "EHLO mail-oa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753101AbaCKHqL convert rfc822-to-8bit (ORCPT ); Tue, 11 Mar 2014 03:46:11 -0400 Received: by mail-oa0-f41.google.com with SMTP id j17so8293405oag.28 for ; Tue, 11 Mar 2014 00:46:10 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1394191196-6425-3-git-send-email-michal.kazior@tieto.com> References: <1394191196-6425-1-git-send-email-michal.kazior@tieto.com> <1394191196-6425-3-git-send-email-michal.kazior@tieto.com> Date: Tue, 11 Mar 2014 08:46:10 +0100 Message-ID: (sfid-20140311_084615_620199_A0D0D61B) Subject: Re: [PATCH 3/3] mac80211: compute chanctx refcount dynamically From: Michal Kazior To: linux-wireless Cc: Johannes Berg , Michal Kazior Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 7 March 2014 12:19, Michal Kazior wrote: > It doesn't make much sense to have a manually > managed chanctx refcount. It isn't performance > critical and it can't be even used outside the > protection of chanctx_mtx. > > With future enhancements to channel contenxt > (namely reservations) refcount accounting will > become more complex and having manually managed > refcount is going to be error-prone and confusing. > > The refcount is now equal to the number of vifs it > is assigned to. However in the future this will > change so keep the refcount/num_assigned_vifs > functions split now. > > Signed-off-by: Michal Kazior Self-NACK. I totally missed how ieee80211_remove_interfaces() works. It removes all interfaces from the list in one go before each is actually stopped. This means refcount computes 0. IOW If you unload a driver with multiple interfaces running you get a nice general protection fault (multiple ieee80211_free_chanctx calls). I'm planning on adding `struct list_head` to sdata and chanctx to be able to iterate over assigned (and reserved, in the future) chanctx. What do you think? Do you have other ideas? Michał