linux-kernel - Re: [PATCH v2 9/9] iio: adc: ad4062: Add GPIO Controller support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAHp75VcJZavRo7TKXAZagDc8Vt4-y-zm+EySyugRtSxSLMGX-Q@mail.gmail.com>
Date: Fri, 5 Dec 2025 14:02:00 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Jorge Marques <gastmaier@...il.com>
Cc: Andy Shevchenko <andriy.shevchenko@...el.com>, Jorge Marques <jorge.marques@...log.com>, 
	Lars-Peter Clausen <lars@...afoo.de>, Michael Hennerich <Michael.Hennerich@...log.com>, 
	Jonathan Cameron <jic23@...nel.org>, David Lechner <dlechner@...libre.com>, 
	Nuno Sá <nuno.sa@...log.com>, 
	Andy Shevchenko <andy@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Jonathan Corbet <corbet@....net>, Linus Walleij <linus.walleij@...aro.org>, 
	Bartosz Golaszewski <brgl@...ev.pl>, linux-iio@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, 
	linux-gpio@...r.kernel.org
Subject: Re: [PATCH v2 9/9] iio: adc: ad4062: Add GPIO Controller support

On Fri, Dec 5, 2025 at 1:53 PM Jorge Marques <gastmaier@...il.com> wrote:
> On Fri, Dec 05, 2025 at 12:21:31AM +0200, Andy Shevchenko wrote:
> > On Thu, Dec 4, 2025 at 11:38 PM Jorge Marques <gastmaier@...il.com> wrote:
> > > On Thu, Nov 27, 2025 at 11:20:54AM +0200, Andy Shevchenko wrote:
> > > > On Wed, Nov 26, 2025 at 04:55:41PM +0100, Jorge Marques wrote:
> > > > > On Mon, Nov 24, 2025 at 12:40:37PM +0200, Andy Shevchenko wrote:
> > > > > > On Mon, Nov 24, 2025 at 10:18:08AM +0100, Jorge Marques wrote:

...

> > > > > > > +       return reg_val == AD4062_GP_STATIC_HIGH ? 1 : 0;
> > > > > >
> > > > > >   return !!(reg_val == AD4062_GP_STATIC_HIGH);
> > > > > >
> > > > > > also will work.
> > > > > >
> > > > >     return reg_val == AD4062_GP_STATIC_HIGH;
> > > >
> > > > Hmm... This will include implicit bool->int. The !! guarantees values 0 or 1,
> > > > but I don't remember about implicit bool->int case.
> >
> > > I don't think the implicit bool->int is an issue, grepping `return .* == .*;`
> > > matches a few methods that return int.
> >
> > Yes, the Q here is the value of true _always_ be promoted to 1?
>
> The relational operator result has type int (c99 6.5.9 Equality
> operators); and when any scalar value is converted to _Bool, the result
> is 0 if the value compares equal to 0; otherwise, the result is 1 (c99
> 6.3.1.2).
> https://www.dii.uchile.cl/~daespino/files/Iso_C_1999_definition.pdf

Okay, thanks for checking this!
So, let's go with a simplified variant then.

> No conversion warnings even when forcing _Bool type.
> There are many usages like this, for example:
>
> drivers/iio/accel/adxl313_core.c @ int adxl313_is_act_inact_ac()
> drivers/iio/light/opt4060.c @ int opt4060_read_event_config()
> drivers/iio/light/tsl2772.c @ int tsl2772_device_id_verify()
> lib/zstd/compress/zstd_fast.c @ int ZSTD_match4Found_branch()
>
> I cannot find many legitimate usage of relational operator with the
> double negation.
>   git ls-files | xargs grep -s 'return !!' | grep '=='

-- 
With Best Regards,
Andy Shevchenko