[RFC PATCH v6 0/3] arm/arm64: fix a migrating irq bug when hotplug cpu

From: Yang Yingliang
Date: Thu Sep 24 2015 - 05:33:42 EST

Changes in v6:
- Don't touch the existing file kernel/irq/migration.c and add
migrating interrupts code to a new file kernel/irq/cpuhotplug.c
suggested by Thomas.
- Change some comments in patch #2 and #3.

Changes in v5:
- remove the macro that guard move_irqs()
- use name irq_migrate_all_off_this_cpu instead of move_irqs

Changes in v4:
- add move_irqs() into kerne/irq/migration.c for cpu hotplug
- use move_irqs() to migrate interrupts on arm/arm64 when cpu is going to down
- split bugfix patch into seperate patches for arm and arm64

Changes in v3:
- introduce config GENERIC_IRQ_MIGRATION for compiling migration.c
- rename migrate_irqs in arch/ia64/kernel/irq.c to avoid compiling error

Changes in v2:
- use the exiting helper to set IRQD_MOVE_PCNTXT flag
- use for_each_active_irq() instead of for_each_irq_desc()
- add some warn messages when affinity is null or do set affinity failed

Hi All,

There is a bug:

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.

As Marc and Will suggested, I refactor the arm/arm64 migrating interrupts
code and fix the migrating irq bug before cpu is offline.

I'm trying let the core code do the migrating interrupts matter. Add the migrating code
to a new file kernel/irq/cpuhotplug.c and make it depend on GENERIC_IRQ_MIGRATION. Fix
the bug by using irq_do_set_affinity. And use the new code to migrate interrupts before
cpu is offline on arm and arm64.

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>

Yang Yingliang (3):
genirq: introduce CONFIG_GENERIC_IRQ_MIGRATION and
arm64: fix a migrating irq bug when hotplug cpu
arm: fix a migrating irq bug when hotplug cpu

arch/arm/Kconfig | 1 +
arch/arm/include/asm/irq.h | 1 -
arch/arm/kernel/irq.c | 62 ----------------------------------------
arch/arm/kernel/smp.c | 2 +-
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/irq.h | 1 -
arch/arm64/kernel/irq.c | 62 ----------------------------------------
arch/arm64/kernel/smp.c | 2 +-
include/linux/irq.h | 2 ++
kernel/irq/Kconfig | 4 +++
kernel/irq/Makefile | 1 +
kernel/irq/cpuhotplug.c | 68 ++++++++++++++++++++++++++++++++++++++++++++
12 files changed, 79 insertions(+), 128 deletions(-)
create mode 100644 kernel/irq/cpuhotplug.c


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