linux-kernel - Re: [PATCH v2] cpufreq: powernv: fix stack bloat and NR

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Message-ID: <20191018050712.qr2axffmbms5h4xb@vireshk-i7>
Date:   Fri, 18 Oct 2019 10:37:12 +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>,
        Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v2] cpufreq: powernv: fix stack bloat and NR_CPUS
 limitation

On 17-10-19, 21:55, John Hubbard 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 due to putting 1024 bytes on the stack:
> 
>     unsigned int chip[256];
> 
> ...and while looking at this, it also has a bug: it fails with a stack
> overrun, if CONFIG_NR_CPUS > 256.
> 
> Fix both problems by dynamically allocating based on CONFIG_NR_CPUS.
> 
> Fixes: 053819e0bf840 ("cpufreq: powernv: Handle throttling due to Pmax capping at chip level")
> 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>
> ---
> 
> Changes since v1: includes Viresh's review commit fixes.
> 
>  drivers/cpufreq/powernv-cpufreq.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)

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

-- 
viresh