Messages in this thread | | | From | Valentin Schneider <> | Subject | Re: [PATCH] irqchip/gic: Convert to handle_strict_flow_irq() | Date | Tue, 17 Aug 2021 01:30:43 +0100 |
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On 15/08/21 07:54, Marc Zyngier wrote: > This is going and-up in a wack-a-mole game. There is probably a bunch > of these all over the place. I'd rather squash it at the root, > i.e. with something like this (untested): > > diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c > index 099bc7e13d1b..601ad3fc47cd 100644 > --- a/kernel/irq/chip.c > +++ b/kernel/irq/chip.c > @@ -410,7 +410,12 @@ void irq_percpu_disable(struct irq_desc *desc, unsigned int cpu) > > void ack_irq(struct irq_desc *desc) > { > - desc->irq_data.chip->irq_ack(&desc->irq_data); > + struct irq_data *data = &desc->irq_data; > + > + while (!data->chip->irq_ack) > + data = data->parent_data; > + > + data->chip->irq_ack(&desc->irq_data); > > if (desc->irq_data.chip->flags & IRQCHIP_AUTOMASKS_FLOW) > irq_state_set_flow_masked(desc); > > We probably need something similar for irq_eoi(). > > This however shows a more fundamental problem, I'm afraid. We set > IRQCHIP_AUTOMASKS_FLOW in the GIC drivers (i.e. at the root), but test > for it at the top of the hierarchy. As soon as we have more than a > single layer of irqchip, this will do the wrong thing (or at least > miss the masking optimisation). >
Yup.
> This probably advocates for moving the flag into the descriptor. This > really makes sense, as the flow is global to the whole stack, not just > to the localised irqchip. >
Are we guaranteed to have
.irq_ack \in {NULL, irq_chip_ack_parent}
for all intermediate (!root) irqchips? I don't see why that wouldn't be the case, and with that in mind what you described makes sense to me.
> In order to restore -next into a working state, I'm temporarily > dropping this series. Hopefully, we can sort this out before the merge > window and reinstate it. >
I'm away from any keyboard for most of this week, but I'll get to it by the weekend.
> Thanks, > > M. > > -- > Without deviation from the norm, progress is not possible.
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