Date: Tue, 28 Jan 2014 22:17:02 +0100
From: Andi Kleen <andi@firstfloor.org>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Ingo Molnar <mingo@kernel.org>, Andi Kleen <andi@firstfloor.org>,
        Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86: Plug racy xAPIC access of CPU hotplug code
Message-ID: <20140128211702.GB11821@two.firstfloor.org>
References: <52E6AFFE.3030004@siemens.com>
 <20140127202252.GA11821@two.firstfloor.org>
 <52E767C2.2090807@siemens.com>
 <20140128115549.GA26230@gmail.com>
 <52E79DEA.3010408@siemens.com>
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> Of course, we still need irqs off during ICR writes. I thought Andi was
> just suggesting to replace preempt_disable with get_cpu, maybe to
> document why we are disabling preemption here.

Yes that was my point.

Also with irq-off you of course still always have races against
the NMI-level machine check.

-Andi
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