From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v7 4/7] sched/core: Prevent race condition between cpuset
 and __sched_setscheduler()
Date: Fri, 5 Apr 2019 14:36:45 +0200
Message-ID: <20190405123645.GT12232@hirez.programming.kicks-ass.net>
References: <20190403084650.4414-1-juri.lelli@redhat.com>
 <20190403084650.4414-5-juri.lelli@redhat.com>
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To: Juri Lelli <juri.lelli@redhat.com>
Cc: mingo@redhat.com, rostedt@goodmis.org, tj@kernel.org, linux-kernel@vger.kernel.org, luca.abeni@santannapisa.it, claudio@evidence.eu.com, tommaso.cucinotta@santannapisa.it, bristot@redhat.com, mathieu.poirier@linaro.org, lizefan@huawei.com, cgroups@vger.kernel.org

On Wed, Apr 03, 2019 at 10:46:47AM +0200, Juri Lelli wrote:
> +static inline void cpuset_read_only_lock(unsigned long *flags)
> +{
> +	local_irq_save(*flags);
> +	preempt_disable();
> +}
> +
> +static inline void cpuset_read_only_unlock(unsigned long *flags)
> +{
> +	local_irq_restore(*flags);
> +	preempt_enable();
> +}

You can ditch the preempt stuff. IRQs disabled already very much implies
!preemptible.