linux-kernel - Re: [PATCH 1/2] sched/rt: Add a helper to test for a RT task

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Date:   Fri, 6 Oct 2017 10:19:37 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Jens Axboe <axboe@...com>, tglx@...utronix.de
Subject: Re: [PATCH 1/2] sched/rt: Add a helper to test for a RT task

On Wed, Oct 04, 2017 at 05:49:00PM +0200, Sebastian Andrzej Siewior wrote:
> This helper returns true if a task has elevated priority which is true
> for RT tasks (SCHED_RR and SCHED_FIFO) and also for SCHED_DEADLINE.
> A task which runs at RT priority due to PI-boosting is not considered as
> one with elevated priority.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> ---
>  include/linux/sched/rt.h | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/include/linux/sched/rt.h b/include/linux/sched/rt.h
> index f93329aba31a..30a86b8178f8 100644
> --- a/include/linux/sched/rt.h
> +++ b/include/linux/sched/rt.h
> @@ -17,6 +17,17 @@ static inline int rt_task(struct task_struct *p)
>  	return rt_prio(p->prio);
>  }
>  
> +static inline bool task_is_elevated(struct task_struct *tsk)

Would you be terribly upset if I rename that? I'm thinking something
like task_is_realtime() better reflects what it does.

> +{
> +	int policy = tsk->policy;
> +
> +	if (policy == SCHED_FIFO || policy == SCHED_RR)
> +		return true;
> +	if (policy == SCHED_DEADLINE)
> +		return true;
> +	return false;
> +}
> +
>  #ifdef CONFIG_RT_MUTEXES
>  /*
>   * Must hold either p->pi_lock or task_rq(p)->lock.
> -- 
> 2.14.2
>