Date: Mon, 2 Mar 2009 14:57:57 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: David Miller <davem@davemloft.net>
Cc: a.p.zijlstra@chello.nl, dbrownell@users.sourceforge.net,
       tglx@linutronix.de, me@felipebalbi.com, linux-kernel@vger.kernel.org,
       linux-input@vger.kernel.org, felipe.balbi@nokia.com,
       dmitry.torokhov@gmail.com, sameo@openedhand.com
Subject: Re: lockdep and threaded IRQs
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On Mon, 02 Mar 2009 14:46:47 -0800 (PST)
David Miller <davem@davemloft.net> wrote:

> From: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Date: Mon, 02 Mar 2009 23:19:31 +0100
> 
> > I state that every !IRQF_DISABLED usage is a bug, either due to broken
> > hardware or broken drivers.
> 
> We'll send you the bill to have everyone's hardware
> replaced :-)

yes, but with what?

No matter how fast all our interrupt handlers are, running them with
local interrupts disabled has to worsen the worst-case interrupt
latency.

I don't see how removing !IRQF_DISABLED improves the kernel - in fact
there's a latency argument for making !IRQF_DISABLED the default.
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