linux-kernel - Re: [PATCH v6 2/8] iio: core: add fixed point parsing with 64-bit parts

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Message-ID: <hrhgmum6zdww7etc6ztchivfqecaaqeeul2bbagzyongkxpaeh@q7x4popwel6d>
Date: Wed, 4 Feb 2026 10:28:05 +0000
From: Rodrigo Alencar <455.rodrigo.alencar@...il.com>
To: Andy Shevchenko <andriy.shevchenko@...el.com>, 
	Rodrigo Alencar <455.rodrigo.alencar@...il.com>
Cc: rodrigo.alencar@...log.com, linux-kernel@...r.kernel.org, 
	linux-iio@...r.kernel.org, devicetree@...r.kernel.org, linux-doc@...r.kernel.org, 
	Jonathan Cameron <jic23@...nel.org>, David Lechner <dlechner@...libre.com>, 
	Andy Shevchenko <andy@...nel.org>, Lars-Peter Clausen <lars@...afoo.de>, 
	Michael Hennerich <Michael.Hennerich@...log.com>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Jonathan Corbet <corbet@....net>
Subject: Re: [PATCH v6 2/8] iio: core: add fixed point parsing with 64-bit
 parts

On 26/02/04 11:57AM, Andy Shevchenko wrote:
> On Wed, Feb 04, 2026 at 09:42:55AM +0000, Rodrigo Alencar wrote:
> > On 26/02/04 03:45AM, Andy Shevchenko wrote:
> > > On Fri, Jan 30, 2026 at 10:06:43AM +0000, Rodrigo Alencar via B4 Relay wrote:
> 
> ...
> 
> > > > +static ssize_t iio_safe_strntou64(const char *str, const char **endp,
> > > > +				  u64 *result, size_t max_chars)
> > > > +{
> > > > +	u64 digit, acc = 0;
> > > > +	ssize_t idx = 0;
> > > > +
> > > > +	while (isdigit(str[idx]) && idx < max_chars) {
> > > > +		digit = str[idx] - '0';
> > > > +		if (unlikely(acc & (~0ull << 60))) {
> > > > +			if (check_mul_overflow(acc, 10, &acc) ||
> > > > +			    check_add_overflow(acc, digit, &acc))
> > > > +				return -ERANGE;
> > > > +		} else {
> > > > +			acc = acc * 10 + digit;
> > > > +		}
> > > > +		idx++;
> > > > +	}
> > > > +
> > > > +	*endp = str + idx;
> > > > +	*result = acc;
> > > > +	return idx;
> > > > +}
> > > 
> > > There is a development in the parse_integer in the lib/. I reviewed that series
> > > and hopefully it will go in. With that done, we better reuse the lib/ function.
> > > 
> > > https://lore.kernel.org/linux-hardening/20260202115451.290173-1-dmantipov@yandex.ru/
> > 
> > In this patch, I see that it updates the overflow check, but I am not
> > seeing that function being exposed to other kernel modules.
> 
> Can the IIO be compiled as a module? If so, then we would need to export that
> function. (Note, we may export only for the exact module(s) in question, so
> nobody else will be able to use it. See EXPORT_SYMBOL_FOR_MODULES() macro.)

Yes, one can have an industrialio.ko.
Then, would it be fine to use:

EXPORT_SYMBOL_FOR_MODULES(_parse_integer_limit, "industrialio");

in lib/kstrtox.c; and:

#include "../../lib/kstrtox.h"

in drivers/iio/industrialio-core.c

that does not look pretty.

-- 
Kind regards,

Rodrigo Alencar