From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2EE27C4332F for ; Thu, 14 Dec 2023 15:27:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1573782AbjLNP1b (ORCPT ); Thu, 14 Dec 2023 10:27:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230298AbjLNP13 (ORCPT ); Thu, 14 Dec 2023 10:27:29 -0500 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF302A3; Thu, 14 Dec 2023 07:27:35 -0800 (PST) X-IronPort-AV: E=McAfee;i="6600,9927,10924"; a="392309700" X-IronPort-AV: E=Sophos;i="6.04,275,1695711600"; d="scan'208";a="392309700" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Dec 2023 07:27:35 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10924"; a="774405344" X-IronPort-AV: E=Sophos;i="6.04,275,1695711600"; d="scan'208";a="774405344" Received: from smile.fi.intel.com ([10.237.72.54]) by orsmga002.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Dec 2023 07:27:32 -0800 Received: from andy by smile.fi.intel.com with local (Exim 4.97) (envelope-from ) id 1rDncY-00000005sVG-0e1D; Thu, 14 Dec 2023 17:27:30 +0200 Date: Thu, 14 Dec 2023 17:27:29 +0200 From: Andy Shevchenko To: Kent Gibson Cc: linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org, brgl@bgdev.pl, linus.walleij@linaro.org Subject: Re: [PATCH v2 4/5] gpiolib: cdev: reduce locking in gpio_desc_to_lineinfo() Message-ID: References: <20231214095814.132400-1-warthog618@gmail.com> <20231214095814.132400-5-warthog618@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 14, 2023 at 11:19:01PM +0800, Kent Gibson wrote: > On Thu, Dec 14, 2023 at 05:10:23PM +0200, Andy Shevchenko wrote: > > On Thu, Dec 14, 2023 at 05:58:13PM +0800, Kent Gibson wrote: > > > Reduce the time holding the gpio_lock by snapshotting the desc flags, > > > rather than testing them individually while holding the lock. > > > > > > Accept that the calculation of the used field is inherently racy, and > > > only check the availability of the line from pinctrl if other checks > > > pass, so avoiding the check for lines that are otherwise in use. ... > > > - spin_lock_irqsave(&gpio_lock, flags); > > > > Shouldn't this be covered by patch 1 (I mean conversion to scoped_guard() > > instead of spinlock)? > > > > Read the cover letter. > Doing that made the change larger, as flags gets removed then restored. > I had also thought the flag tests would get indented then unindented, but > if we use guard() the indentation should remain unchanged. I'm fine with that as I pointed out (have you received that mail? I had problems with my mail server) the dflags is better semantically, so restoration with _different_ name is fine. > Can do it in 1 if you are happy with the flags declaration being > removed in patch 1 and restored in 4. Definitely. -- With Best Regards, Andy Shevchenko