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ARM: CPU hotplug: ensure we migrate all IRQs off a downed CPU

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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: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2011-07-21 15:14:21 +01:00
parent ca15af19ac
commit 78359cb86b
1 changed files with 28 additions and 11 deletions
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39
arch/arm/kernel/irq.c
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@ -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);