linux-kernel - Re: [PATCH v3] cpufreq: powernv: fix stack bloat and hard limit on num cpus

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Message-ID: <CAKohpomBZPYyX_u2xSzE4UenR0s3eFo5SOmDZ=4NLVcD_pA5iQ@mail.gmail.com>
Date:   Thu, 31 Oct 2019 14:52:53 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     John Hubbard <jhubbard@...dia.com>
Cc:     Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH v3] cpufreq: powernv: fix stack bloat and hard limit on
 num cpus

On Thu, 31 Oct 2019 at 10:52, John Hubbard <jhubbard@...dia.com> wrote:
>
> The following build warning occurred on powerpc 64-bit builds:
>
> drivers/cpufreq/powernv-cpufreq.c: In function 'init_chip_info':
> drivers/cpufreq/powernv-cpufreq.c:1070:1: warning: the frame size of
> 1040 bytes is larger than 1024 bytes [-Wframe-larger-than=]
>
> This is with a cross-compiler based on gcc 8.1.0, which I got from:
>   https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/x86_64/8.1.0/
>
> The warning is due to putting 1024 bytes on the stack:
>
>     unsigned int chip[256];
>
> ...and it's also undesirable to have a hard limit on the number of
> CPUs here.
>
> Fix both problems by dynamically allocating based on num_possible_cpus,
> as recommended by Michael Ellerman.
>
> Fixes: 053819e0bf840 ("cpufreq: powernv: Handle throttling due to Pmax capping at chip level")
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Cc: Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>
> Cc: Preeti U Murthy <preeti@...ux.vnet.ibm.com>
> Cc: Viresh Kumar <viresh.kumar@...aro.org>
> Cc: Rafael J. Wysocki <rjw@...ysocki.net>
> Cc: linux-pm@...r.kernel.org
> Cc: linuxppc-dev@...ts.ozlabs.org
> Signed-off-by: John Hubbard <jhubbard@...dia.com>
> ---

Acked-by: Viresh Kumar <viresh.kumar@...aro.org>