linux-kernel - Re: [v3.4-rc1] ACPI regression bisected

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Message-ID: <alpine.LFD.2.02.1204191125520.2542@ionos>
Date:	Thu, 19 Apr 2012 11:30:31 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Andi Kleen <ak@...ux.intel.com>
cc:	Matthew Garrett <mjg59@...f.ucam.org>,
	Jörg Otte <jrg.otte@...glemail.com>,
	linux-kernel@...r.kernel.org, Len Brown <lenb@...nel.org>
Subject: Re: [v3.4-rc1] ACPI regression bisected

On Thu, 12 Apr 2012, Andi Kleen wrote:

> 
> > > I feared that. So now is the question whether there is a way to mask
> > > the interrupt at the "device" level.
> 
> Probably not. Len?
> 
> > If not, I could be persuaded to provide a mechanism to force thread
> > all interrupts which are on that line, if there's a good argument to
> > do so.
> 
> Hmm, we could probably just use a work queue for this instead. I guess i drank
> the threaded
> interrupt kool aid too much when I did the patch :-)
> 
> I'll switch over to a workqueue.

That still requires that you can silence the interrupt at the device
level in the first place unless you play silly games with
disable_irq_nosync(), which is even worse than having a
IRQF_FORCE_ONESHOT mechanism in the core.

If you go the workqueue way, then you basically split the interrupt
into a hard irq context and a thread handler. So it's the same to
request a real threaded interrupt with a primary and a thread handler
and return IRQF_WAKE_THREAD conditionally from the primary handler,
when you need the thread context for further processing.

Thoughts?

	tglx

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