linux-kernel - Re: [PATCH] cpufreq: kyro: Reduce frame-size of qcom_cpufreq_kryo

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Date:   Wed, 20 Feb 2019 21:56:40 +0530
From:   Amit Kucheria <amit.kucheria@...aro.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>, Ilia Lin <ilia.lin@...nel.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Arnd Bergmann <arnd@...db.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpufreq: kyro: Reduce frame-size of qcom_cpufreq_kryo_probe()

On Wed, Feb 20, 2019 at 4:44 PM Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> With the introduction of commit 846a415bf440 ("arm64: default NR_CPUS to
> 256"), we have started getting following compilation warning:
>
> qcom-cpufreq-kryo.c:168:1: warning: the frame size of 2160 bytes is larger than 2048 bytes [-Wframe-larger-than=]
>
> Fix that by dynamically allocating opp_tables and freeing it later.
>
> Compile tested only.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
>  drivers/cpufreq/qcom-cpufreq-kryo.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/cpufreq/qcom-cpufreq-kryo.c b/drivers/cpufreq/qcom-cpufreq-kryo.c
> index 1c8583cc06a2..6888cb6db2ef 100644
> --- a/drivers/cpufreq/qcom-cpufreq-kryo.c
> +++ b/drivers/cpufreq/qcom-cpufreq-kryo.c
> @@ -75,7 +75,7 @@ static enum _msm8996_version qcom_cpufreq_kryo_get_msm_id(void)
>
>  static int qcom_cpufreq_kryo_probe(struct platform_device *pdev)
>  {
> -       struct opp_table *opp_tables[NR_CPUS] = {0};
> +       struct opp_table **opp_tables;
>         enum _msm8996_version msm8996_version;
>         struct nvmem_cell *speedbin_nvmem;
>         struct device_node *np;
> @@ -133,6 +133,10 @@ static int qcom_cpufreq_kryo_probe(struct platform_device *pdev)
>         }
>         kfree(speedbin);
>
> +       opp_tables = kcalloc(num_possible_cpus(), sizeof(*opp_tables), GFP_KERNEL);
> +       if (!opp_tables)
> +               return -ENOMEM;
> +

Perhaps add a comment above that that actual opp_table is allocated in
the loop below because of dev_pm_opp_set_supported_hw?

I was staring at this for a few minutes wondering why you needed this
kcalloc before I realised that opp_tables (missed the 's') is a
temporary array of pointers. :-)

Otherwise,

Reviewed-by: Amit Kucheria <amit.kucheria@...aro.org>

>         for_each_possible_cpu(cpu) {
>                 cpu_dev = get_cpu_device(cpu);
>                 if (NULL == cpu_dev) {
> @@ -149,6 +153,8 @@ static int qcom_cpufreq_kryo_probe(struct platform_device *pdev)
>                 }
>         }
>
> +       kfree(opp_tables);
> +
>         cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
>                                                           NULL, 0);
>         if (!IS_ERR(cpufreq_dt_pdev))
> @@ -163,6 +169,7 @@ static int qcom_cpufreq_kryo_probe(struct platform_device *pdev)
>                         break;
>                 dev_pm_opp_put_supported_hw(opp_tables[cpu]);
>         }
> +       kfree(opp_tables);
>
>         return ret;
>  }
> --
> 2.21.0.rc0.269.g1a574e7a288b
>