linux-kernel - Re: [PATCH] sched/core: remove unnecessary unlikely() in push_xx

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Date:   Fri, 9 Nov 2018 01:58:02 +0800
From:   Frank Lee <tiny.windzz@...il.com>
To:     mingo@...hat.com, peterz@...radead.org, mingo@...nel.org
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched/core: remove unnecessary unlikely() in push_xx_task

Hi mingo:
    What is your point of view?
--Yangtao

On Sun, Nov 4, 2018 at 1:26 AM Yangtao Li <tiny.windzz@...il.com> wrote:
>
> WARN_ON() already contains an unlikely(), so it's not necessary to
> use WARN_ON(1).
>
> Signed-off-by: Yangtao Li <tiny.windzz@...il.com>
> ---
>  kernel/sched/deadline.c | 4 +---
>  kernel/sched/rt.c       | 4 +---
>  2 files changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index 91e4202b0634..8b5d964d59c5 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -2041,10 +2041,8 @@ static int push_dl_task(struct rq *rq)
>                 return 0;
>
>  retry:
> -       if (unlikely(next_task == rq->curr)) {
> -               WARN_ON(1);
> +       if (WARN_ON(next_task == rq->curr))
>                 return 0;
> -       }
>
>         /*
>          * If next_task preempts rq->curr, and rq->curr
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index 2e2955a8cf8f..0efd58563c80 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -1810,10 +1810,8 @@ static int push_rt_task(struct rq *rq)
>                 return 0;
>
>  retry:
> -       if (unlikely(next_task == rq->curr)) {
> -               WARN_ON(1);
> +       if (WARN_ON(next_task == rq->curr))
>                 return 0;
> -       }
>
>         /*
>          * It's possible that the next_task slipped in of
> --
> 2.17.0
>