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Message-ID: <87o8kw93n4.fsf@nanos.tec.linutronix.de>
Date: Tue, 20 Oct 2020 20:02:55 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
Daniel Bristot de Oliveira <bristot@...hat.com>
Subject: Re: sched: Reenable interrupts in do sched_yield()
On Tue, Oct 20 2020 at 11:38, Steven Rostedt wrote:
> On Tue, 20 Oct 2020 16:46:55 +0200
> Thomas Gleixner <tglx@...utronix.de> wrote:
>
>> - /*
>> - * Since we are going to call schedule() anyway, there's
>> - * no need to preempt or enable interrupts:
>
> I think the above comment still makes sense, just needs to be tweeked:
>
> /*
> * Since we are going to call schedule() anyway, there's
> * no need to allow preemption after releasing the rq lock.
>> - */
>
> Especially, since we are now enabling interrupts, which is likely to
> trigger a preemption.
sched_preempt_enable_no_resched() still enables preemption. It just
avoids the check. And it still allows preemption when an interrupt
triggering preemption happens between sched_preempt_enable_no_resched()
and __schedule() disabling preemption/interrupts.
So no, your new variant is just differently bogus and misleading.
Thanks,
tglx
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