linux-kernel - Re: [PATCH v3 2/2] x86: Fix /proc/cpuinfo cpumask warning

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Date:   Mon, 31 Oct 2022 09:58:57 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Andrew Jones <ajones@...tanamicro.com>
Cc:     Yury Norov <yury.norov@...il.com>, x86@...nel.org,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Stafford Horne <shorne@...il.com>,
        openrisc@...ts.librecores.org,
        Michael Ellerman <mpe@...erman.id.au>,
        "open list:LINUX FOR POWERPC PA SEMI PWRFICIENT" 
        <linuxppc-dev@...ts.ozlabs.org>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        linux-s390@...r.kernel.org
Subject: Re: [PATCH v3 2/2] x86: Fix /proc/cpuinfo cpumask warning

On Mon, Oct 31, 2022 at 09:06:04AM +0100, Andrew Jones wrote:
>  The valid cpumask range is [0, nr_cpu_ids) and cpumask_next() always
>  returns a CPU ID greater than its input, which results in its input
>  range being [-1, nr_cpu_ids - 1). Ensure showing CPU info avoids
>  triggering error conditions in cpumask_next() by stopping its loop

What error conditions?

What would happen if @n is outside of the valid range?

-- 
Regards/Gruss,
    Boris.

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