linux-kernel - Re: [PATCH] x86/lib: Fix num_digits() signed overflow for INT

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Message-ID: <bdd4b13c-4ab3-42ba-b024-6e38d8f03404@zytor.com>
Date: Tue, 20 Jan 2026 11:50:41 -0800
From: "H. Peter Anvin" <hpa@...or.com>
To: Borislav Petkov <bp@...en8.de>,
        David Desobry <david.desobry@...malgen.com>
Cc: tglx@...nel.org, mingo@...hat.com, dave.hansen@...ux.intel.com,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/lib: Fix num_digits() signed overflow for INT_MIN

On 2026-01-20 11:16, Borislav Petkov wrote:
> 
> Absolutely. We do that all the time and it used to work back then. Hell, it
> works fine for CPU numbers but if someone wants to give it INT_MIN... we
> didn't care about that. We needed it for this gunk:
> 
>   a17bce4d1dce ("x86/boot: Further compress CPUs bootup message")
> 

For negative numbers? Dave Hansen pointed out that we currently don't ever
pass negative numbers, in which case it would make more sense to have the
function simply take an unsigned int.

	-hpa