linux-kernel - Re: [PATCH] uapi: bitops: use UAPI-safe variant of BITS_PER

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Message-ID: <20250708082027-acf3e21a-8627-4cbe-9ccb-6d872eec2918@linutronix.de>
Date: Tue, 8 Jul 2025 08:26:49 +0200
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Yury Norov <yury.norov@...il.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>, 
	Vincent Mailhol <mailhol.vincent@...adoo.fr>, Rasmus Villemoes <linux@...musvillemoes.dk>, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] uapi: bitops: use UAPI-safe variant of BITS_PER_LONG
 again (2)

On Tue, Jul 01, 2025 at 05:37:40PM -0400, Yury Norov wrote:
> On Mon, Jun 30, 2025 at 10:52:54AM -0400, Yury Norov wrote:
> > On Mon, Jun 30, 2025 at 03:02:18PM +0200, Thomas Weißschuh wrote:
> > > BITS_PER_LONG does not exist in UAPI headers, so can't be used by the UAPI
> > > __GENMASK(). Instead __BITS_PER_LONG needs to be used.
> > > 
> > > When __GENMASK() was introduced in commit 3c7a8e190bc5 ("uapi: introduce uapi-friendly macros for GENMASK"),
> > > the code was fine. A broken revert in 1e7933a575ed ("uapi: Revert "bitops: avoid integer overflow in GENMASK(_ULL)"")
> > > introduced the incorrect usage of BITS_PER_LONG.
> > > That was fixed in commit 11fcf368506d ("uapi: bitops: use UAPI-safe variant of BITS_PER_LONG again").
> > > But a broken sync of the kernel headers with the tools/ headers in
> > > commit fc92099902fb ("tools headers: Synchronize linux/bits.h with the kernel sources")
> > > undid the fix.
> > > 
> > > Reapply the fix and while at it also fix the tools header.
> > > 
> > > Fixes: fc92099902fb ("tools headers: Synchronize linux/bits.h with the kernel sources")
> > > Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
> > 
> > Acked-by: Yury Norov (NVIDIA) <yury.norov@...il.com>
> > 
> > Arnaldo, do you want to move it yourself or with my branch?
> 
> OK, added this in bitmap-for-next together with the MAINTAINERS patch.

Thanks!

Any chance to get the fix into v6.16 again?
This currently triggers warnings in my code in -next [0], which is intended
to go into v6.17.

[0] https://lore.kernel.org/all/20250708160830.36ddf20f@canb.auug.org.au/


Thomas