linux-kernel - Re: [PATCH 11/21] drivers: don't use GENMASK() in FIELD_PREP

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: <432db4d2-1f36-4531-b0b3-2a06ae682fd1@sirena.org.uk>
Date: Mon, 27 Oct 2025 13:10:40 +0000
From: Mark Brown <broonie@...nel.org>
To: "Yury Norov (NVIDIA)" <yury.norov@...il.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Nicolas Frattaroli <nicolas.frattaroli@...labora.com>,
	Sandy Huang <hjc@...k-chips.com>,
	Heiko Stübner <heiko@...ech.de>,
	Andy Yan <andy.yan@...k-chips.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
	Shreeya Patel <shreeya.patel@...labora.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Jaehoon Chung <jh80.chung@...sung.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Nicolas Frattaroli <frattaroli.nicolas@...il.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
	dri-devel@...ts.freedesktop.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-media@...r.kernel.org, kernel@...labora.com,
	linux-mmc@...r.kernel.org, linux-sound@...r.kernel.org,
	Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: Re: [PATCH 11/21] drivers: don't use GENMASK() in FIELD_PREP_WM16()

On Sat, Oct 25, 2025 at 12:40:10PM -0400, Yury Norov (NVIDIA) wrote:

> Recently added FIELD_PREP_WM16() in a few places uses GENMASK. It's
> confusing and may mislead readers. Switch to BITS() or FIRST_BITS()
> as appropriate.

This doesn't seem to line up with the actual change, you're not altering
FIELD_PREP_WM16() at all but rather altering things that use it.

As mentioned in submitting-patches.rst when submitting a patch series
you should supply a cover letter for that patch series which describes
the overall content of the series.  This helps people understand what
they are looking at and how things fit together.

> ---
>  drivers/gpu/drm/rockchip/rockchip_lvds.h             | 2 +-
>  drivers/gpu/drm/rockchip/rockchip_vop2_reg.c         | 4 ++--
>  drivers/media/platform/synopsys/hdmirx/snps_hdmirx.h | 4 ++--
>  drivers/mmc/host/dw_mmc-rockchip.c                   | 4 ++--
>  drivers/soc/rockchip/grf.c                           | 4 ++--
>  sound/soc/rockchip/rockchip_i2s_tdm.h                | 2 +-
>  6 files changed, 10 insertions(+), 10 deletions(-)

It doesn't help to send changes to unrelated subsystems in one patch
either...

> --- a/sound/soc/rockchip/rockchip_i2s_tdm.h
> +++ b/sound/soc/rockchip/rockchip_i2s_tdm.h
> @@ -287,7 +287,7 @@ enum {
>  #define I2S_TDM_RXCR	(0x0034)
>  #define I2S_CLKDIV	(0x0038)
>  
> -#define HIWORD_UPDATE(v, h, l)	(FIELD_PREP_WM16_CONST(GENMASK((h), (l)), (v)))
> +#define HIWORD_UPDATE(v, h, l)	(FIELD_PREP_WM16_CONST(BITS((l), (h)), (v)))

This is adjusting the implementation of something that takes in h, l to
use l, h which if anything seems likely to introduce confusion, and
definitely feels well into bikeshed territory.  I don't *super* care but
I'm having a hard time seeing the benefit.

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