Re: [patch 0/2] Run interrupt handlers always with interrupts disabled

Andi Kleen
2010-03-26T10:12:47Z

On Fri, Mar 26, 2010 at 11:08:53AM +0100, Peter Zijlstra wrote:
> On Fri, 2010-03-26 at 09:59 +0000, Alan Cox wrote:
> > > As long as it's rare (which it is) i dont see a problem: you can enable
> > > interrupts in the handler by using local_irq_enable(), like the IDE PIO
> > > drivers do. That way it's documented a bit better as well, because it shows
> > > the precise source of the latency, with a big comment explaining it, etc.
> >
> > I don't think it's as rare as you think particularly in embedded, and the
> > moment you start explicitly using local_irq_enable() you've simply moved
> > the underlying problem back and made it far harder to grep for.
>
> We've got local_irq_enable_in_hardirq() which should be used and can
> easily be grep'ed for.
>
> But yes, I would much prefer to simply convert these known slow handlers
> to threaded interrupts.

That could be potentially hundreds in old obscure drivers all over the tree.

-Andi

--
ak@linux.intel.com -- Speaking for myself only.