Re: lockdep and threaded IRQs

Andrew Morton
2009-03-02T23:59:41Z

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.