linux-kernel - Re: [PATCH] sched/fair: Fix an unused function warning

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Date:   Wed, 21 Apr 2021 16:15:48 +0200
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Vincent Donnefort <vincent.donnefort@....com>,
        Paul Turner <pjt@...gle.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] sched/fair: Fix an unused function warning

Hi Arnd,

A similar patch has already been merged in tip/sched/core:
161890837554.29796.9442405099846421634.tip-bot2@...-bot2

Regards,
Vincent

On Wed, 21 Apr 2021 at 16:01, Arnd Bergmann <arnd@...nel.org> wrote:
>
> From: Arnd Bergmann <arnd@...db.de>
>
> Without CONFIG_NO_HZ_COMMON, there is now a warning about update_nohz_stats
> after the last caller outside the #ifdef was removed
>
> kernel/sched/fair.c:8433:13: error: 'update_nohz_stats' defined but not used [-Werror=unused-function]
>  8433 | static bool update_nohz_stats(struct rq *rq)
>
> Simplify the function by removing the #ifdef inside it and move it into
> the block in which it gets called.
>
> Fixes: 0826530de3cb ("sched/fair: Remove update of blocked load from newidle_balance")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  kernel/sched/fair.c | 40 ++++++++++++++++++----------------------
>  1 file changed, 18 insertions(+), 22 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index df2083d2dd0c..7c3edbb5ec70 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -8430,28 +8430,6 @@ group_type group_classify(unsigned int imbalance_pct,
>         return group_has_spare;
>  }
>
> -static bool update_nohz_stats(struct rq *rq)
> -{
> -#ifdef CONFIG_NO_HZ_COMMON
> -       unsigned int cpu = rq->cpu;
> -
> -       if (!rq->has_blocked_load)
> -               return false;
> -
> -       if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))
> -               return false;
> -
> -       if (!time_after(jiffies, READ_ONCE(rq->last_blocked_load_update_tick)))
> -               return true;
> -
> -       update_blocked_averages(cpu);
> -
> -       return rq->has_blocked_load;
> -#else
> -       return false;
> -#endif
> -}
> -
>  /**
>   * update_sg_lb_stats - Update sched_group's statistics for load balancing.
>   * @env: The load balancing environment.
> @@ -10123,6 +10101,24 @@ static inline int on_null_domain(struct rq *rq)
>  }
>
>  #ifdef CONFIG_NO_HZ_COMMON
> +static bool update_nohz_stats(struct rq *rq)
> +{
> +       unsigned int cpu = rq->cpu;
> +
> +       if (!rq->has_blocked_load)
> +               return false;
> +
> +       if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))
> +               return false;
> +
> +       if (!time_after(jiffies, READ_ONCE(rq->last_blocked_load_update_tick)))
> +               return true;
> +
> +       update_blocked_averages(cpu);
> +
> +       return rq->has_blocked_load;
> +}
> +
>  /*
>   * idle load balancing details
>   * - When one of the busy CPUs notice that there may be an idle rebalancing
> --
> 2.29.2
>