linux-kernel - Re: [PATCH] Prevent nested interrupts when the IRQ stack is near overflowing v2

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Message-ID: <20100326061029.GU20695@one.firstfloor.org>
Date:	Fri, 26 Mar 2010 07:10:29 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andi Kleen <andi@...stfloor.org>, x86@...nel.org,
	LKML <linux-kernel@...r.kernel.org>, jesse.brandeburg@...el.com
Subject: Re: [PATCH] Prevent nested interrupts when the IRQ stack is near overflowing v2

> Now, I think (and sincerely) that the SCSI situation is likely long since 
> fixed, but we have thousands and thousands of drivers, and these kinds of 
> things are very hard to notice automatically. Are there any cases around 
> that still have busy-loop delays based on real-time in their irq handlers? 
> I simply don't know.

This case was already broken back when the x86-64 port used to run
with NMI watchdog on by default, because any IO exception handling
with interrupts off would trigger the NMI watchdog eventually.

I remember having to add bandaids to Fusion for this a long time ago.

Of course ISA drivers might still do it.

-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only.
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