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: <2a4e69f3ac4fb6cb131735d3cb598223b71bc90b.camel@gmail.com>
Date: Tue, 12 Nov 2024 14:28:05 +0100
From: Nuno Sá <noname.nuno@...il.com>
To: Uwe Kleine-König <u.kleine-koenig@...libre.com>, 
 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

On Tue, 2024-11-12 at 11:15 +0100, Uwe Kleine-König wrote:
> 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.
> 

Not commenting on the debate between using the extension or not but I totally agree
with Uwe about hiding the return in the macro.

- Nuno Sá
>