Re: [PATCH] ipipe: Fix ipipe level irq end

[Greg Gallagher <greg@embeddedgreg.com>]

On Thu, Feb 17, 2022 at 4:15 AM Jan Kiszka <jan.kiszka@siemens.com> wrote:

> On 17.02.22 09:48, Gunter Grau via Xenomai wrote:
> > The following commit in the vanilla kernel introduced
> > a check for the cached interrupt mask flag in mask_irq():
> >
> > bf22ff45bed6 ("genirq: Avoid unnecessary low level irq function calls")
> >
> > This means if the flag is not serviced correctly
> > the real bit in the hardware interrupt controller may not be
> > cleared or set.
> > The __ipipe_end_level_irq() function does not follow this rule.
> > It unmasks the bit in the hardware without setting the cached flags
> > accordingly. So after the first level interrupt is finished the
> > mask cache has a wrong state. If now the next interrupt fires,
> > the mask_irq() function will not really mask the interrupt in
> > the hardware which causes a interrupt storm after reenabeling
> > the hard irqs.
> > The fix now also updates the shadow flag correctly.
> > ---
> >  kernel/irq/chip.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
> > index 7c03e2931189..ff9a8b3f33db 100644
> > --- a/kernel/irq/chip.c
> > +++ b/kernel/irq/chip.c
> > @@ -988,6 +988,7 @@ void __ipipe_ack_level_irq(struct irq_desc *desc)
> >  void __ipipe_end_level_irq(struct irq_desc *desc)
> >  {
> >         desc->irq_data.chip->irq_unmask(&desc->irq_data);
> > +       irq_state_clr_masked(desc);
> >  }
> >
> >  void __ipipe_ack_fasteoi_irq(struct irq_desc *desc)
> > --
> > 2.25.1
> >
>
> Thanks, applied to ipipe-noarch. I had to do that manually as you email
> client managed the patch (tabs->spaces, trailing spaces removed). Use
> git-send-email or a client that avoids this mangling.
>
> Greg, I will apply this to ipipe-x86 (4.19-cip and 5.4), could you do
> the same for arm and arm64?
>
> Thanks,
> Jan
>
> --
> Siemens AG, Technology


> Competence Center Embedded Linux


Yep, I’ve applied the patch locally, I’ll update arm and arm64 shortly.

-Greg

>
>