linux-kernel - Re: [PATCH 1/2] sched/rt.c: pick and check task if double_lock

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Date:   Thu, 12 Apr 2018 08:10:39 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Li Bin <huawei.libin@...wei.com>
Cc:     <peterz@...radead.org>, <mingo@...hat.com>,
        <linux-kernel@...r.kernel.org>, <guohanjun@...wei.com>
Subject: Re: [PATCH 1/2] sched/rt.c: pick and check task if
 double_lock_balance() unlock the rq

On Thu, 12 Apr 2018 18:58:54 +0800
Li Bin <huawei.libin@...wei.com> wrote:

> @@ -1726,13 +1746,10 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
>  			 * We had to unlock the run queue. In
>  			 * the mean time, task could have
>  			 * migrated already or had its affinity changed.
> -			 * Also make sure that it wasn't scheduled on its rq.
>  			 */
> -			if (unlikely(task_rq(task) != rq ||
> -				     !cpumask_test_cpu(lowest_rq->cpu, &task->cpus_allowed) ||
> -				     task_running(rq, task) ||
> -				     !rt_task(task) ||
> -				     !task_on_rq_queued(task))) {
> +			struct task_struct *next_task = pick_next_pushable_task(rq);

Could you declare next_task above the comment. It's better styling.

	struct task_struct *next_task;
	/*
	 * Comment
	 */
	next_task = pick_next_pushable_task(rq);


-- Steve

> +			if (unlikely(next_task != task ||
> +				     !cpumask_test_cpu(lowest_rq->cpu, &task->cpus_allowed))) {
>  
>  				double_unlock_balance(rq, lowest_rq);
>  				lowest_rq = NULL;
> @@ -1752,26 +1769,6 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)