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irqchip/gic, gic-v3: Make SGIs use handle_percpu_devid_irq()

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handle_percpu_devid_fasteoi_ipi() states:

 * The biggest difference with the IRQ version is that the interrupt is
 * EOIed early, as the IPI could result in a context switch, and we need to
 * make sure the IPI can fire again

All that can actually happen scheduler-wise within the handling of an IPI
is the raising of TIF_NEED_RESCHED (and / or folding thereof into
preempt_count); see scheduler_ipi() or sched_ttwu_pending() for instance.

Said flag / preempt_count is evaluated some time later before returning to
whatever context was interrupted, and this gates a call to
preempt_schedule_irq() (arm64_preempt_schedule_irq() in arm64).

Per the above, SGI's do not need a different handler than PPI's, so make
them use the same (handle_percpu_devid_irq).

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201109094121.29975-2-valentin.schneider@arm.com
This commit is contained in:
Valentin Schneider 2020-11-09 09:41:17 +00:00 committed by Marc Zyngier
parent 550c1424ac
commit 6abbd69889
2 changed files with 1 additions and 13 deletions
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6
drivers/irqchip/irq-gic-v3.c
View File

@ -1302,12 +1302,6 @@ static int gic_irq_domain_map(struct irq_domain *d, unsigned int irq,
switch (__get_intid_range(hw)) {
case SGI_RANGE:
irq_set_percpu_devid(irq);
irq_domain_set_info(d, irq, hw, chip, d->host_data,
handle_percpu_devid_fasteoi_ipi,
NULL, NULL);
break;
case PPI_RANGE:
case EPPI_RANGE:
irq_set_percpu_devid(irq);

8
drivers/irqchip/irq-gic.c
View File

@ -1005,13 +1005,7 @@ static int gic_irq_domain_map(struct irq_domain *d, unsigned int irq,
struct irq_data *irqd = irq_desc_get_irq_data(irq_to_desc(irq));
switch (hw) {
case 0 ... 15:
irq_set_percpu_devid(irq);
irq_domain_set_info(d, irq, hw, &gic->chip, d->host_data,
handle_percpu_devid_fasteoi_ipi,
NULL, NULL);
break;
case 16 ... 31:
case 0 ... 31:
irq_set_percpu_devid(irq);
irq_domain_set_info(d, irq, hw, &gic->chip, d->host_data,
handle_percpu_devid_irq, NULL, NULL);