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 86F31C00144 for ; Fri, 29 Jul 2022 14:37:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237181AbiG2OhJ (ORCPT ); Fri, 29 Jul 2022 10:37:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43216 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237137AbiG2OhG (ORCPT ); Fri, 29 Jul 2022 10:37:06 -0400 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9D0066170E for ; Fri, 29 Jul 2022 07:37:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1659105425; x=1690641425; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=QFxIPJPgK4IPpJ/HviS1EILZsgjtlw3yJGq/7HtHu+I=; b=fV5yWjzw/TIMmuDnV2j8c99bwRVpGxDYFV90qmICcADrSdDbsfDoi0LC +Uz8NxrVNKxW9X6LfHCcxxWHN1SJ/7Z3sJHgwxJFMI8s6FNzB2Mf4i0HY lWBHA+HZmf4sNlytmC/fsTzhJvP4eQ5VqkyY+DWz9FqnYWJMiEHiRV7z3 pcTpjSuuHMBwNhUTmhK1xHouUeTQCNIxT0xOQjC6x10q249VSogIqLx37 kK3dtxb4cBjLGo3TKaicqRI1AbCIIVm0fjE30fjA0+JBug7nwboFdrQRi ohWJwW9DMIbfycZ4BgXmKbS/u6dxp9/shpaO2t4L2noadgDxoSVBZbNnp A==; X-IronPort-AV: E=McAfee;i="6400,9594,10423"; a="287532998" X-IronPort-AV: E=Sophos;i="5.93,201,1654585200"; d="scan'208";a="287532998" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jul 2022 07:36:56 -0700 X-IronPort-AV: E=Sophos;i="5.93,201,1654585200"; d="scan'208";a="704215764" Received: from smile.fi.intel.com ([10.237.72.54]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jul 2022 07:36:53 -0700 Received: from andy by smile.fi.intel.com with local (Exim 4.96) (envelope-from ) id 1oHR6g-001eZv-1G; Fri, 29 Jul 2022 17:36:50 +0300 Date: Fri, 29 Jul 2022 17:36:50 +0300 From: Andy Shevchenko To: Matthew Wilcox Cc: Mark Rutland , Jagdish Gediya , linux-kernel@vger.kernel.org, linux-mm@kvack.org, ying.huang@intel.com, dave.hansen@intel.com, Jonathan.Cameron@huawei.com, adobriyan@gmail.com, akpm@linux-foundation.org, rf@opensource.cirrus.com, pmladek@suse.com, will@kernel.org Subject: Re: [PATCH v3 1/2] lib/kstrtox.c: Add "false"/"true" support to kstrtobool() Message-ID: References: <20220426180203.70782-1-jvgediya@linux.ibm.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 Fri, Jul 29, 2022 at 05:35:26PM +0300, Andy Shevchenko wrote: > On Mon, Jul 25, 2022 at 04:21:11PM +0100, Matthew Wilcox wrote: > > On Mon, Jul 25, 2022 at 03:55:27PM +0100, Mark Rutland wrote: > > > On Tue, Apr 26, 2022 at 11:32:02PM +0530, Jagdish Gediya wrote: > > > > At many places in kernel, It is necessary to convert sysfs input > > > > to corrosponding bool value e.g. "false" or "0" need to be converted > > > > to bool false, "true" or "1" need to be converted to bool true, > > > > places where such conversion is needed currently check the input > > > > string manually, kstrtobool() can be utilized at such places but > > > > currently it doesn't have support to accept "false"/"true". > > > > > > > > Add support to accept "false"/"true" as valid string in kstrtobool(). > > > > > > > > Signed-off-by: Jagdish Gediya > > > > Reviewed-by: Matthew Wilcox (Oracle) > > > > > > I've just spotted that this broke arm64's "rodata=full" command line option, > > > > That isn't a documented option. > > > > rodata= [KNL] > > on Mark read-only kernel memory as read-only (default). > > off Leave read-only kernel memory writable for debugging. > > > > Hopefully this is an object lesson in why you need to update the > > documentation when you extend a feature. > > > > > since "full" gets parsed as 'f' = FALSE, when previously that would have been > > > rejected. So anyone passing "rodata=full" on the command line will have rodata > > > disabled, which is not what they wanted. > > > > > > The current state of things is a bit messy (we prase the option twice because > > > arch code needs it early), and we can probably fix that with some refactoring, > > > but I do wonder if we actually want to open up the sysfs parsing to accept > > > anything *beginning* with [tTfF] rather than the full "true" and "false" > > > strings as previously, or whether it's worth reverting this for now in case > > > anything else is affected. > > > > Well, that's going to break people who've started using the new option. > > As a quick fix, how about only allowing either "f\0" or "fa"? > > I think we need to be more strict in kstrtobool(), i.e. 'f\0' ('t\0') and 'fal' > ('tru') perhaps? Actually kstrtobool() has been designed as a generic parser that should have lowest priority. It means that the code that uses it should take care of any other custom cases _before_ calling for kstrtobool(). -- With Best Regards, Andy Shevchenko