Re: [PATCH] arm: irq: fix the affinity when migrate a irq

From: Sudeep Holla
Date: Fri Aug 15 2014 - 04:43:55 EST


Hi Neil,

On 15/08/14 08:31, Neil Zhang wrote:
Commit ffde1de64012 ("irqchip: Gic: Support forced affinity setting")
has enable the forcing cpu affinity of interrupts for gic.

The current code of migrate_one_irq will pass the current affinity mask
to irq_set_affinity with force is true, it may select the cpu being
offlined as the target CPU again, then the interrupt won't be migrated
correctly.


I had posted similar patch [1] a while ago and the discussion[2] did not conclude. We need feedback from Thomas Gleixner.

Regards,
Sudeep

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2014-May/254838.html
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2014-June/265191.html

Signed-off-by: Neil Zhang <zhangwm@xxxxxxxxxxx>
---
arch/arm/kernel/irq.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
index 2c42576..6f5a878 100644
--- a/arch/arm/kernel/irq.c
+++ b/arch/arm/kernel/irq.c
@@ -167,11 +167,10 @@ static bool migrate_one_irq(struct irq_desc *desc)
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;
+ if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids)
ret = true;
- }

+ affinity = cpu_online_mask;
c = irq_data_get_irq_chip(d);
if (!c->irq_set_affinity)
pr_debug("IRQ%u: unable to set affinity\n", d->irq);


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