linux-kernel - Re: [PATCH v4 4/6] iio: light: stk3310: use dev_err

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

Message-ID: <4ibd5tgpt3uzbmouqdiiv5pvfxebo5qsmgn3xh6rlb73qevatv@cajznxqnlca3>
Date: Tue, 12 Nov 2024 11:15:54 +0100
From: Uwe Kleine-König <u.kleine-koenig@...libre.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>, 
	Aren <aren@...cevolution.org>
Cc: Jonathan Cameron <jic23@...nel.org>, 
	Lars-Peter Clausen <lars@...afoo.de>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>, 
	Jernej Skrabec <jernej.skrabec@...il.com>, Samuel Holland <samuel@...lland.org>, 
	Kaustabh Chakraborty <kauschluss@...root.org>, Barnabás Czémán <trabarni@...il.com>, 
	Ondrej Jirman <megi@....cz>, linux-iio@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-sunxi@...ts.linux.dev, Dragan Simic <dsimic@...jaro.org>, phone-devel@...r.kernel.org
Subject: Re: [PATCH v4 4/6] iio: light: stk3310: use dev_err_probe where
 possible

Hello Andy, hello Aren,

On Mon, Nov 11, 2024 at 11:44:51AM +0200, Andy Shevchenko wrote:
> On Sun, Nov 10, 2024 at 04:34:30PM -0500, Aren wrote:
> > On Sun, Nov 10, 2024 at 09:52:32PM +0200, Andy Shevchenko wrote:
> > > Sun, Nov 10, 2024 at 02:14:24PM -0500, Aren kirjoitti:
> 
> You can do it differently
> 
> #define STK3310_REGFIELD(name)							\
> do {										\
> 	data->reg_##name =							\
> 		devm_regmap_field_alloc(dev, regmap, stk3310_reg_field_##name);	\
> 	if (IS_ERR(data->reg_##name))						\
> 		return dev_err_probe(dev, PTR_ERR(data->reg_##name),		\
> 				     "reg field alloc failed.\n");		\
> } while (0)
> 
> > #define STK3310_REGFIELD(name) ({						\
> > 	data->reg_##name = devm_regmap_field_alloc(dev, regmap,			\
> > 						   stk3310_reg_field_##name);   \
> > 	if (IS_ERR(data->reg_##name))						\
> > 		return dev_err_probe(dev, PTR_ERR(data->reg_##name),		\
> > 				     "reg field alloc failed\n");		\
> > })
> 
> I am against unneeded use of GNU extensions.
> 
> > > > replacing "do { } while (0)" with "({ })" and deindenting could make
> > > > enough room to clean this up the formatting of this macro though.
> > > 
> > > do {} while (0) is C standard, ({}) is not.
> > 
> > ({ }) is used throughout the kernel, and is documented as such[1]. I
> > don't see a reason to avoid it, if it helps readability.
> 
> I don't see how it makes things better here, and not everybody is familiar with
> the concept even if it's used in the kernel here and there. Also if a tool is
> being used in one case it doesn't mean it's suitable for another.

Just to throw in my subjective view here: I don't expect anyone with
some base level knowledge of C will have doubts about the semantics of
({ ... }) and compared to that I find do { ... } while (0) less optimal,
because it's more verbose and when spotting the "do {" part, the
semantic only gets clear when you also see the "while (0)". Having said
that I also dislike the "do" starting on column 0, IMHO the RHS of the
#define should be intended.

So if you ask me, this is not an unneeded use of an extension. The
extension is used to improve readabilty and I blame the C standard to
not support this syntax.

While I'm in critics mode: I consider hiding a return in a macro bad
style.

Best regards
Uwe

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)