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Date:   Wed, 7 Oct 2020 09:22:58 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Qais Yousef <qais.yousef@arm.com>
Cc:     tglx@linutronix.de, mingo@kernel.org, linux-kernel@vger.kernel.org,
        bigeasy@linutronix.de, swood@redhat.com,
        valentin.schneider@arm.com, juri.lelli@redhat.com,
        vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
        bristot@redhat.com, vincent.donnefort@arm.com, tj@kernel.org
Subject: Re: [PATCH -v2 12/17] sched,rt: Use cpumask_any*_distribute()
Message-ID: <20201007072258.GA2628@hirez.programming.kicks-ass.net>
References: <20201005145717.346020688@infradead.org>
 <20201005150922.156231026@infradead.org>
 <20201006155527.w6jck2rgk64t45wm@e107158-lin.cambridge.arm.com>
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On Tue, Oct 06, 2020 at 04:55:27PM +0100, Qais Yousef wrote:
> > +int cpumask_any_distribute(const struct cpumask *srcp)
> > +{
> > +	int next, prev;
> > +
> > +	/* NOTE: our first selection will skip 0. */
> > +	prev = __this_cpu_read(distribute_cpu_mask_prev);
> 
> We had a discussion then that __this_cpu*() variant assumes preemption being
> disabled and it's safer to use this_cpu*() variant instead. Still holds true
> here?

I think we ended up with not caring. We wanted a 'random' value, we get
a 'random' value from a 'random' CPU, still works ;-)