[RFC PATCH v4 3/4] arm64: fix a migrating irq bug when hotplug cpu

From: Yang Yingliang
Date: Thu Sep 17 2015 - 06:23:39 EST


When cpu is disabled, all irqs will be migratged to another cpu.
In some cases, a new affinity is different, it needed to be coppied
to irq's affinity. But if the type of irq is LPI, it's affinity will
not be coppied because of irq_set_affinity's return value. Fix it by
using irq_do_set_affinity.

And migrating interrupts is a core code matter, so use the generic
function move_irqs() to migrate interrupts in kernel/irq/migration.c.

Cc: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx>
Cc: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/irq.h | 1 -
arch/arm64/kernel/irq.c | 62 --------------------------------------------
arch/arm64/kernel/smp.c | 2 +-
4 files changed, 2 insertions(+), 64 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7d95663..e0cac17 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -410,6 +410,7 @@ config NR_CPUS

config HOTPLUG_CPU
bool "Support for hot-pluggable CPUs"
+ select GENERIC_IRQ_MIGRATION
help
Say Y here to experiment with turning CPUs off and on. CPUs
can be controlled through /sys/devices/system/cpu.
diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h
index bbb251b..0916929 100644
--- a/arch/arm64/include/asm/irq.h
+++ b/arch/arm64/include/asm/irq.h
@@ -7,7 +7,6 @@

struct pt_regs;

-extern void migrate_irqs(void);
extern void set_handle_irq(void (*handle_irq)(struct pt_regs *));

static inline void acpi_irq_init(void)
diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
index 11dc3fd..9f17ec0 100644
--- a/arch/arm64/kernel/irq.c
+++ b/arch/arm64/kernel/irq.c
@@ -27,7 +27,6 @@
#include <linux/init.h>
#include <linux/irqchip.h>
#include <linux/seq_file.h>
-#include <linux/ratelimit.h>

unsigned long irq_err_count;

@@ -54,64 +53,3 @@ void __init init_IRQ(void)
if (!handle_arch_irq)
panic("No interrupt controller found.");
}
-
-#ifdef CONFIG_HOTPLUG_CPU
-static bool migrate_one_irq(struct irq_desc *desc)
-{
- struct irq_data *d = irq_desc_get_irq_data(desc);
- const struct cpumask *affinity = irq_data_get_affinity_mask(d);
- 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;
- ret = true;
- }
-
- c = irq_data_get_irq_chip(d);
- if (!c->irq_set_affinity)
- pr_debug("IRQ%u: unable to set affinity\n", d->irq);
- else if (c->irq_set_affinity(d, affinity, false) == IRQ_SET_MASK_OK && ret)
- cpumask_copy(irq_data_get_affinity_mask(d), affinity);
-
- return ret;
-}
-
-/*
- * 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;
- struct irq_desc *desc;
- unsigned long flags;
-
- local_irq_save(flags);
-
- for_each_irq_desc(i, desc) {
- bool affinity_broken;
-
- raw_spin_lock(&desc->lock);
- affinity_broken = migrate_one_irq(desc);
- raw_spin_unlock(&desc->lock);
-
- if (affinity_broken)
- pr_warn_ratelimited("IRQ%u no longer affine to CPU%u\n",
- i, smp_processor_id());
- }
-
- local_irq_restore(flags);
-}
-#endif /* CONFIG_HOTPLUG_CPU */
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index dbdaacd..492e2e4 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -232,7 +232,7 @@ int __cpu_disable(void)
/*
* OK - migrate IRQs away from this CPU
*/
- migrate_irqs();
+ move_irqs();

/*
* Remove this CPU from the vm mask set of all processes.
--
2.5.0


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