linux-kernel - Re: [tip:sched/core] sched/fair: Use rq_lock/unlock in online_fair_sched

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Message-ID: <dfc8f652-ca98-e30a-546f-e6a2df36e33a@arm.com>
Date:   Fri, 9 Aug 2019 18:21:22 +0200
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     pauld@...hat.com, vincent.guittot@...aro.org, hpa@...or.com,
        linux-kernel@...r.kernel.org, peterz@...radead.org,
        mingo@...hat.com, tglx@...utronix.de, mingo@...nel.org,
        linux-tip-commits@...r.kernel.org
Subject: Re: [tip:sched/core] sched/fair: Use rq_lock/unlock in
 online_fair_sched_group

On 8/8/19 1:01 PM, tip-bot for Phil Auld wrote:

[...]

> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 19c58599e967..d9407517dae9 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -10281,18 +10281,18 @@ err:
>  void online_fair_sched_group(struct task_group *tg)
>  {
>  	struct sched_entity *se;
> +	struct rq_flags rf;
>  	struct rq *rq;
>  	int i;
>  
>  	for_each_possible_cpu(i) {
>  		rq = cpu_rq(i);
>  		se = tg->se[i];
> -
> -		raw_spin_lock_irq(&rq->lock);
> +		rq_lock(rq, &rf);
>  		update_rq_clock(rq);
>  		attach_entity_cfs_rq(se);
>  		sync_throttle(tg, i);
> -		raw_spin_unlock_irq(&rq->lock);
> +		rq_unlock(rq, &rf);
>  	}
>  }

Shouldn't this be:

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d9407517dae9..1054d2cf6aaa 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10288,11 +10288,11 @@ void online_fair_sched_group(struct task_group
*tg)
        for_each_possible_cpu(i) {
                rq = cpu_rq(i);
                se = tg->se[i];
-               rq_lock(rq, &rf);
+               rq_lock_irq(rq, &rf);
                update_rq_clock(rq);
                attach_entity_cfs_rq(se);
                sync_throttle(tg, i);
-               rq_unlock(rq, &rf);
+               rq_unlock_irq(rq, &rf);
        }
 }

Currently, you should get a 'inconsistent lock state' warning with
CONFIG_PROVE_LOCKING.