Return-path: Received: from mail-wi0-f172.google.com ([209.85.212.172]:33822 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755716AbbA3NWS convert rfc822-to-8bit (ORCPT ); Fri, 30 Jan 2015 08:22:18 -0500 Received: by mail-wi0-f172.google.com with SMTP id h11so2993253wiw.5 for ; Fri, 30 Jan 2015 05:22:17 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1422623054.1919.18.camel@sipsolutions.net> References: <1422607287-12289-1-git-send-email-michal.kazior@tieto.com> <1422621086-28970-1-git-send-email-michal.kazior@tieto.com> <1422621086-28970-3-git-send-email-michal.kazior@tieto.com> <1422621903.1919.7.camel@sipsolutions.net> <1422623054.1919.18.camel@sipsolutions.net> Date: Fri, 30 Jan 2015 14:22:16 +0100 Message-ID: (sfid-20150130_142220_996474_92CF6E1F) Subject: Re: [PATCH v2 2/7] ath10k: implement chanctx API From: Michal Kazior To: Johannes Berg Cc: "ath10k@lists.infradead.org" , linux-wireless Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 30 January 2015 at 14:04, Johannes Berg wrote: > On Fri, 2015-01-30 at 14:02 +0100, Michal Kazior wrote: > >> I recall that at least there's one case where using these helpers is >> impossible: drv_config() which can be called while mac80211 is already >> holding iflist_mtx. ath10k needs to iterate over vifs and issue >> blocking commands sometimes so it can't use atomic/rcu versions >> either. > > If you wanted to use it, I wouldn't be averse to adding a locked version > that can only be used inside a few of such callbacks. With appropriate > lockdep warnings that would be safe enough, I think. You'd probably have to add quite a few mutex_lock(iflist_mtx) around drv_*() calls (not directly but somewhere at their call trees) to guarantee driver can use lock-free iterate() version (which doesn't exist yet). This could be tricky. Michał