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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: ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1658762496; a=rsa-sha256; cv=none; b=sy4CuvGtn3F+kD15vrLuAimvmz3YX5iGpbCrnGFJwF0iDe1tbYpOzjqvUuOzesWGAQNtC+ nbY0hy8bui0UtqCq2Yppe5qxBZaYloxAiwGcv24VAGF/kHWaR31WIVNIC5lCE7httElj7v PsluOV6DrvVacUGVm5Km5Bi7HyfXGX4= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=W93GVpt2; dmarc=none; spf=none (imf16.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1658762496; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=23s7JvNMsvF2AHH6z4dTYojuhFk5VWrqF+qCO533ufA=; b=S3qN4GyHTTlcSRXJyVWokTMC+1ny9urCcseDpHSR0cIaZUXXZDZzKpNqUMGxu9rhb/zod2 9ZiNNFZqbBqQ8vn8VZC55YMUO6PVcDzsTxdqstFqUwsMBFjyJUU8ZqN4GJ9GU4O5Knpx7K DecPG9jVsUMJdkJjtPLpYEKo/vwQ7DE= X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: B5A6F1800C5 Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=W93GVpt2; dmarc=none; spf=none (imf16.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-Stat-Signature: ze1x93o41tw9nnq4a5a7bnh8p9jt48px X-HE-Tag: 1658762493-767449 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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"?