Messages in this thread | | | Date | Tue, 04 Jul 2023 16:31:13 +0100 | From | Marc Zyngier <> | Subject | Re: [PATCH] irqchip/gic-v3: Workaround for GIC-700 erratum 2941627 |
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On Tue, 04 Jul 2023 16:27:45 +0100, Lorenzo Pieralisi <lpieralisi@kernel.org> wrote: > > On Tue, Jul 04, 2023 at 03:44:50PM +0100, Marc Zyngier wrote: > > [...] > > > > + return !((gic_irq_in_rdist(d)) || gic_irq(d) >= 8192 || > > > + cpumask_equal(irq_data_get_effective_affinity_mask(d), > > > + cpumask_of(smp_processor_id()))); > > > > I dislike this statement for multiple reasons: > > > > - it is written as a negation, making it harder than strictly > > necessary to parse as it is the opposite of the comment above > > > > - gic_irq_in_rdist() and gic_irq(d) >= 8192 are two ways of checking > > the interrupt range -- maybe we should just do that > > > > - cpumask_equal() is *slow* if you have more that 64 CPUs, something > > that is increasingly common -- a better option would be to check > > whether the current CPU is in the mask or not, which would be enough > > as we only have a single affinity bit set > > > > - smp_processor_id() can check for preemption, which is pointless > > here, as we're doing things under the irq_desc raw spinlock. > > > > I would expect something like: > > > > enum gic_intid_range range = get_intid_range(d); > > > > return (range == SGI_RANGE || range == ESPI_RANGE) && > > !cpumask_test_cpu(raw_smp_processor_id(), > > irq_data_get_effective_affinity_mask(d)); > > > > s/SGI/SPI - just noticed, for the records.
Indeed. As you can tell, I didn't really test the damn thing...
Thanks,
M.
-- Without deviation from the norm, progress is not possible.
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