Commit 5e7371de authored Apr 27, 2012 by Will Deacon Committed by Russell King Apr 28, 2012

ARM: 7406/1: hotplug: copy the affinity mask when forcefully migrating IRQs



When a CPU is hotplugged off, we migrate any IRQs currently affine to it
away and onto another online CPU by calling the irq_set_affinity
function of the relevant interrupt controller chip. This function
returns either IRQ_SET_MASK_OK or IRQ_SET_MASK_OK_NOCOPY, to indicate
whether irq_data.affinity was updated.

If we are forcefully migrating an interrupt (because the affinity mask
no longer identifies any online CPUs) then we should update the IRQ
affinity mask to reflect the new CPU set. Failure to do so can
potentially leave /proc/irq/n/smp_affinity identifying only offline
CPUs, which may confuse userspace IRQ balancing daemons.

This patch updates migrate_one_irq to copy the affinity mask when
the interrupt chip returns IRQ_SET_MASK_OK after forcefully changing the
affinity of an interrupt.

Cc: stable@vger.kernel.org
Reported-by: Leif Lindholm <leif.lindholm@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

parent 6fa99b7f

arch/arm/kernel/irq.c

+3 −3

Original line number	Original line	Diff line number	Diff line
	@@ -155,10 +155,10 @@ static bool migrate_one_irq(struct irq_desc *desc)
	}		}

	c = irq_data_get_irq_chip(d);		c = irq_data_get_irq_chip(d);
	if (c->irq_set_affinity)		if (!c->irq_set_affinity)
	c->irq_set_affinity(d, affinity, true);
	else
	pr_debug("IRQ%u: unable to set affinity\n", d->irq);		pr_debug("IRQ%u: unable to set affinity\n", d->irq);
			else if (c->irq_set_affinity(d, affinity, true) == IRQ_SET_MASK_OK && ret)
			cpumask_copy(d->affinity, affinity);

	return ret;		return ret;
	}		}

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