linux-kernel - Re: [PATCH 32/32] x86/boot/e820: Move index increments outside accessors in e820__update

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Message-ID: <aT50ynhxiqW_Zi0-@gmail.com>
Date: Sun, 14 Dec 2025 09:26:50 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Nikolay Borisov <nik.borisov@...e.com>
Cc: linux-kernel@...r.kernel.org, Andy Shevchenko <andy@...nel.org>,
	Arnd Bergmann <arnd@...nel.org>, Borislav Petkov <bp@...en8.de>,
	Juergen Gross <jgross@...e.com>, "H . Peter Anvin" <hpa@...or.com>,
	Kees Cook <keescook@...omium.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Mike Rapoport <rppt@...nel.org>,
	Paul Menzel <pmenzel@...gen.mpg.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	David Woodhouse <dwmw@...zon.co.uk>
Subject: Re: [PATCH 32/32] x86/boot/e820: Move index increments outside
 accessors in e820__update_table()

* Nikolay Borisov <nik.borisov@...e.com> wrote:

>
>
> On 5/15/25 15:05, Ingo Molnar wrote:
> > This kind of code:
> >
> >	change_point[chg_idx++]->entry  = &entries[idx];
> >
> > Can be a bit confusing to human readers, and GCC-15 started
> > warning about these patterns.
> >
> > Move the index increment outside the accessor.
> >
> > Suggested-by: Andy Shevchenko <andy@...nel.org>
> > Signed-off-by: Ingo Molnar <mingo@...nel.org>
> > Cc: Arnd Bergmann <arnd@...nel.org>
> > Cc: David Woodhouse <dwmw@...zon.co.uk>
> > Cc: H. Peter Anvin <hpa@...or.com>
> > Cc: Kees Cook <keescook@...omium.org>
> > Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> > Cc: Mike Rapoport (Microsoft) <rppt@...nel.org>
> > ---
> >   arch/x86/kernel/e820.c | 6 ++++--
> >   1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> > index 10c6e7dc72d7..afb312620c82 100644
> > --- a/arch/x86/kernel/e820.c
> > +++ b/arch/x86/kernel/e820.c
> > @@ -421,9 +421,11 @@ __init int e820__update_table(struct e820_table *table)
> >	for (idx = 0; idx < table->nr_entries; idx++)	{
> >		if (entries[idx].size != 0) {
> nit: The level of nesting can easily be reduced by doing
> if (entries[idx].size == 0)
>	continue;
> >			change_point[chg_idx]->addr	= entries[idx].addr;
> > -			change_point[chg_idx++]->entry	= &entries[idx];
> > +			change_point[chg_idx]->entry	= &entries[idx];
> > +			chg_idx++;
>
> nit: I have to agree with H. Peter Anvin that this seems somewhat odd to me
> as well.

OK, I've dropped this change.

Thanks,

	Ingo