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

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Message-ID: <20180412081237.2a212c95@gandalf.local.home>
Date:   Thu, 12 Apr 2018 08:12:37 -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 2/2] sched/deadline.c: pick and check task if
 double_lock_balance() unlock the rq

On Thu, 12 Apr 2018 18:58:55 +0800
Li Bin <huawei.libin@...wei.com> wrote:

> @@ -1965,11 +1985,9 @@ static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
>  
>  		/* Retry if something changed. */
>  		if (double_lock_balance(rq, later_rq)) {
> -			if (unlikely(task_rq(task) != rq ||
> -				     !cpumask_test_cpu(later_rq->cpu, &task->cpus_allowed) ||
> -				     task_running(rq, task) ||
> -				     !dl_task(task) ||
> -				     !task_on_rq_queued(task))) {
> +			struct task_struct *next_task = pick_next_pushable_dl_task(rq);

I would do the same thing here, and add the comment from rt.c as it
is the same reason.

-- Steve

> +			if (unlikely(next_task != task ||
> +						!cpumask_test_cpu(later_rq->cpu, &task->cpus_allowed))) {
>  				double_unlock_balance(rq, later_rq);
>  				later_rq = NULL;