linux-kernel - Re: [PATCH v2 1/1] arm: topology: remove cpu

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Message-ID: <CAKfTPtBz8oDtNYMkQ=UuB50V3__7EOaSPtdr_yES=GBjRNzgAw@mail.gmail.com>
Date:   Thu, 19 Oct 2017 09:32:18 +0200
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Dietmar Eggemann <dietmar.eggemann@....com>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        LAK <linux-arm-kernel@...ts.infradead.org>,
        Russell King <linux@...linux.org.uk>,
        Juri Lelli <juri.lelli@...il.com>,
        Brendan Jackman <Brendan.Jackman@....com>
Subject: Re: [PATCH v2 1/1] arm: topology: remove cpu_efficiency

Hi Dietmar,

On 18 October 2017 at 12:37, Dietmar Eggemann <dietmar.eggemann@....com> wrote:
> Hi Vincent,
>
> On 17/10/17 13:28, Vincent Guittot wrote:
>> Hi Dietmar,
>>
>> On 12 October 2017 at 16:00, Dietmar Eggemann <dietmar.eggemann@....com> wrote:
>>> Remove the 'cpu_efficiency/clock-frequency dt property' based solution
>>> to set cpu capacity which was only working for Cortex-A15/A7 arm
>>> big.LITTLE systems.
>>>
>>> I.e. the 'capacity-dmips-mhz' based solution is now the only one. It is
>>> shared between arm and arm64 and works for every big.LITTLE system no
>>> matter which core types it consists of.
>>>
>>> Cc: Russell King <linux@....linux.org.uk>
>>> Cc: Vincent Guittot <vincent.guittot@...aro.org>
>>> Cc: Juri Lelli <juri.lelli@...il.com>
>>> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>
>
> [...]
>
>>> @@ -111,76 +50,15 @@ static void __init parse_dt_topology(void)
>>>                         continue;
>>>                 }
>>>
>>> -               if (topology_parse_cpu_capacity(cn, cpu)) {
>>> +               if (topology_parse_cpu_capacity(cn, cpu))
>>>                         of_node_put(cn);
>>
>> We should call the of_node_put unconditionally  to balance the
>> of_get_cpu_node, isn't it ?
>> Note that this problem is also present without your change
>
> Thanks for the review. Brendan mentioned this the other day already.
>
> I could add an additional patch to the v3 with this code change. What do
> you think?

The changes looks good to me

>
> diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
> index 15cc131ae387..81ec42333489 100644
> --- a/arch/arm/kernel/topology.c
> +++ b/arch/arm/kernel/topology.c
> @@ -41,6 +41,7 @@ static void __init parse_dt_topology(void)
>                 pr_err("No CPU information found in DT\n");
>                 return;
>         }
> +       of_node_put(cn);
>
>         for_each_possible_cpu(cpu) {
>                 /* too early to use cpu->of_node */
> @@ -50,8 +51,8 @@ static void __init parse_dt_topology(void)
>                         continue;
>                 }
>
> -               if (topology_parse_cpu_capacity(cn, cpu))
> -                       of_node_put(cn);
> +               topology_parse_cpu_capacity(cn, cpu);
> +               of_node_put(cn);
>         }
>
>         topology_normalize_cpu_scale();
>
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