linux-kernel - Re: [PATCH v2 0/2] bus: CCN/CCI: Fix use of smp_processor

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Message-ID: <20171003171847.GG4931@leverpostej>
Date:   Tue, 3 Oct 2017 18:18:47 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Pawel Moll <pawel.moll@....com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/2] bus: CCN/CCI: Fix use of smp_processor_id()

On Tue, Oct 03, 2017 at 06:14:11PM +0100, Marc Zyngier wrote:
> I've just noticed that both the CCI and CCN drivers have a small
> buglet in that they call smp_processor_id() from preemptible context,
> which is frown upon (having just booted a 4.13 kernel with
> DEBUG_PREEMPT on my Seattle, I was surprised to be greeted with a nice
> backtrace...).
> 
> I've tested the CCN patch on the same Seatle box, but I've only
> compile-tested the equivalent CCI patch (which is obviously correct --
> famous last words...).
> 
> Thanks,
> 
> 	M.
> 
> * From v1: Keep the current CPU refcount until we have registered the
>   CPU notifiers, making sure we don't race against a surprise hotplug
>   off.
> 
> Marc Zyngier (2):
>   bus: arm-ccn: Fix use of smp_processor_id() in preemptible context
>   bus: arm-cci: Fix use of smp_processor_id() in preemptible context

For both:

Acked-by: Mark Rutland <mark.rutland@....com>

Thanks,
Mark.