netdev - Re: [PATCH v2 08/16] bitfield: Simplify __BF_FIELD_CHECK

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Message-ID: <aVF8uQxjz9trZAHY@smile.fi.intel.com>
Date: Sun, 28 Dec 2025 20:53:45 +0200
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: David Laight <david.laight.linux@...il.com>
Cc: Jonathan Cameron <jonathan.cameron@...wei.com>,
	Yury Norov <yury.norov@...il.com>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Crt Mori <cmo@...exis.com>,
	Richard Genoud <richard.genoud@...tlin.com>,
	Luo Jie <quic_luoj@...cinc.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
	"David S . Miller" <davem@...emloft.net>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Andreas Noever <andreas.noever@...il.com>,
	Yehezkel Bernat <YehezkelShB@...il.com>,
	Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
Subject: Re: [PATCH v2 08/16] bitfield: Simplify __BF_FIELD_CHECK_REG()

On Wed, Dec 17, 2025 at 10:31:55PM +0000, David Laight wrote:
> On Wed, 17 Dec 2025 10:26:18 +0000
> Jonathan Cameron <jonathan.cameron@...wei.com> wrote:
> > On Fri, 12 Dec 2025 19:37:13 +0000
> > david.laight.linux@...il.com wrote:

...

> > > +	BUILD_BUG_ON_MSG((mask) + 0U + 0UL + 0ULL >			\
> > > +			 ~0ULL >> (64 - 8 * sizeof (reg)),		\  
> > 
> > Trivial.  sizeof(reg) is much more comment syntax in kernel code.
>                                      (common)
> 
> Hmm. sizeof is an operator not a function.
> Its argument is either a variable/expression or a bracketed type
> (I don't usually put variables in brackets).
> So 'sizeof(reg)' is nearly as bad as 'return(reg)'.

Yet, it's a style used de facto in the Linux kernel. I am with Jonathan on this.

-- 
With Best Regards,
Andy Shevchenko