Re: [patch 1/2] genirq: Run irq handlers with interrupts disabled

Peter Zijlstra
2010-04-02T21:32:44Z

On Fri, 2010-04-02 at 23:09 +0200, Pavel Machek wrote:
> On Fri 2010-04-02 22:42:51, Thomas Gleixner wrote:
> > On Fri, 2 Apr 2010, Pavel Machek wrote:
> >
> > > On Wed 2010-03-31 13:16:37, Thomas Gleixner wrote:
> > > > On Tue, 30 Mar 2010, Andi Kleen wrote:
> > > >
> > > > > > Why not simply force IRQF_DISABLED for all MSI interrupts. That still
> > > > > > allows nesting for non MSI ones, but it limits the chance of throwing
> > > > > > up reasonably well. That's a two liner.
> > > > > >
> > > > > > Can you please test whether it resolves the issue at hand ?
> > > > >
> > > > > Sorry for the late answer. Got confirmation that this patch
> > > > > fixes the test case. Thanks.
> > > >
> > > > Ok, I'll push it linus wards and cc stable. I think thats the least
> > > > intrusive safe bet we can have right now.
> > >
> > > stable? I'd say thats way too intrusive for -stable...
> >
> > So we better let the possible stack overruns unaddressed ?
>
> -stable should have no regressions, first and foremost. And this is
> pretty certain to introduce some, at least on low-powered system with
> serial ports.
>
> So yes, it is probably better to let the possible stack overruns
> unaddressed. We have lived with them for 15 years or so...
>
> (Alternatively, just make the irq stacks bigger? Or just take Andi's
> patch, which solves the overruns, and only introduces latency
> regressions when it would otherwise crash?)

You've got serial ports with MSI interrupts?