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Commit 78359cb8 authored by Russell King's avatar Russell King
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ARM: CPU hotplug: ensure we migrate all IRQs off a downed CPU 



Our selection of interrupts to consider for IRQ migration is sub-
standard.  We were potentially including per-CPU interrupts in our
migration strategy, but omitting chained interrupts.  This caused
some interrupts to remain on a downed CPU.

We were also trying to migrate interrupts which were not migratable,
resulting in an OOPS.

Instead, iterate over all interrupts, skipping per-CPU interrupts
or interrupts whose affinity does not include the downed CPU, and
attempt to set the affinity for every one else if their chip
implements irq_set_affinity().

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent ca15af19

arch/arm/kernel/irq.c

+28 −11
Original line number Diff line number Diff line
@@ -131,46 +131,63 @@ int __init arch_probe_nr_irqs(void) 


#ifdef CONFIG_HOTPLUG_CPU



static bool migrate_one_irq(struct irq_data *d)

static bool migrate_one_irq(struct irq_desc *desc)

{

	struct irq_data *d = irq_desc_get_irq_data(desc);

	const struct cpumask *affinity = d->affinity;

	struct irq_chip *c;

	bool ret = false;



	/*

	 * If this is a per-CPU interrupt, or the affinity does not

	 * include this CPU, then we have nothing to do.

	 */

	if (irqd_is_per_cpu(d) || !cpumask_test_cpu(smp_processor_id(), affinity))

		return false;



	if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {

		affinity cpu_online_mask;

		affinity = cpu_online_mask;

		ret = true;

	}



	d->chip->irq_set_affinity(d, affinity, true);

	c = irq_data_get_irq_chip(d);

	if (c->irq_set_affinity)

		c->irq_set_affinity(d, affinity, true);

	else

		pr_debug("IRQ%u: unable to set affinity\n", d->irq);



	return ret;

}



/*

 * The CPU has been marked offline.  Migrate IRQs off this CPU.  If

 * the affinity settings do not allow other CPUs, force them onto any

 * The current CPU has been marked offline.  Migrate IRQs off this CPU.

 * If the affinity settings do not allow other CPUs, force them onto any

 * available CPU.

 *

 * Note: we must iterate over all IRQs, whether they have an attached

 * action structure or not, as we need to get chained interrupts too.

 */

void migrate_irqs(void)

{

	unsigned int i, cpu = smp_processor_id();

	unsigned int i;

	struct irq_desc *desc;

	unsigned long flags;



	local_irq_save(flags);



	for_each_irq_desc(i, desc) {

		struct irq_data *d = &desc->irq_data;

		bool affinity_broken = false;



		if (!desc)

			continue;



		raw_spin_lock(&desc->lock);

		if (desc->action != NULL &&

		    cpumask_test_cpu(smp_processor_id(), d->affinity))

			affinity_broken = migrate_one_irq(d);

		affinity_broken = migrate_one_irq(desc);

		raw_spin_unlock(&desc->lock);



		if (affinity_broken && printk_ratelimit())

			pr_warning("IRQ%u no longer affine to CPU%u\n", i, cpu);

			pr_warning("IRQ%u no longer affine to CPU%u\n", i,

				smp_processor_id());

	}



	local_irq_restore(flags);