linux-kernel - Re: Perhaps a side effect regarding NMI returns

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Message-ID: <20111129212855.GR24062@one.firstfloor.org>
Date:	Tue, 29 Nov 2011 22:28:55 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	Paul Turner <pjt@...gle.com>
Subject: Re: Perhaps a side effect regarding NMI returns

> I'm curious to what remote events can be set by an NMI that wont take
> affect in what the NMI interrupted. I would think that NMIs should be
> treated as if they didn't exist, because they should not be calling
> anything that sets NEED_RESCHED or grabbing locks and such.

Hmm, i thought there were cases where we checked if it was in
kernel mode instead of IPIng, and assume the check is done when
returning.

But cannot come up with a concrete example right now. It may have
been wrong. Or I forgot it :)

You're right anything with interrupts should be fine because
it's just blocked.

-Andi

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