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 B0E29C43334 for ; Mon, 25 Jul 2022 15:22:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236533AbiGYPWZ (ORCPT ); Mon, 25 Jul 2022 11:22:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37758 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236329AbiGYPVo (ORCPT ); Mon, 25 Jul 2022 11:21:44 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3143EC12 for ; Mon, 25 Jul 2022 08:21:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=23s7JvNMsvF2AHH6z4dTYojuhFk5VWrqF+qCO533ufA=; b=W93GVpt2rUDlsdSMVN2WEF1b1L 92Q01zwXWnid6eWuVyRdi9ZCfnSJo5uxeqjPUcnJFtexKzHFcGPAQ5cbW1y5MSMsZh1I5Wv8L92yS K2I794tOgXYlEmbsaE9+zvqHuK/k7VGgB+Z/MjCJ9+hXCVeOclQ4ExRSi2LiGSq0su206Iu+uMzuX 5G8SuXckL4PQbem6QS/Je8gPoF+z5hSd/8MzfPrwISD/NBNBKbNMIt0FshZSJVEBzPTdwyiycU1+t A/iI7WaxWY7AXC0sLGW3tXXkAIkBBzpGNstPLEN4ZtOAogqqqbgkpqofPWXc5r5Pk/j6dTQ72Cl5n 0nR3VqUg==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1oFztP-001Cg9-BV; Mon, 25 Jul 2022 15:21:11 +0000 Date: Mon, 25 Jul 2022 16:21:11 +0100 From: Matthew Wilcox To: Mark Rutland Cc: 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, andriy.shevchenko@linux.intel.com, 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: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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"?