[RFC PATCH v1 0/4] arm/arm64: fix a migrating irq bug when hotplug cpu
Jiang Liu
jiang.liu at linux.intel.com
Sun Sep 6 01:07:26 PDT 2015
On 2015/9/6 12:23, Yang Yingliang wrote:
> 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 while cpu is offline.
>
> I'm trying let the core code do the migrating interrupts matter. kernel/irq/migration.c
> depends on CONFIG_GENERIC_PENDING_IRQ, so I make it selected by CONFIG_SMP and
> CONFIG_HOTPLUG_CPU and rename it to CONFIG_GENERIC_IRQ_MIGRATION for more general.
> When CONFIG_GENERIC_IRQ_MIGRATION is enabled, an interrupt whose state_use_accessors
> is not set with IRQD_MOVE_PCNTXT won't be migrated immediately in irq_set_affinity_locked().
> So introduce irq_settings_set_move_pcntxt() helper to set the state in gic_irq_domain_map().
>
> With the above preparation, move the migrating interrupts code into kernel/irq/migration.c
> and fix the bug by using irq_do_set_affinity().
Hi Yingliang,
As we are going to move migrate_irqs() to generic kernel
code, and powerpc, metag, xtensa, sh, ia64 mn10300 also defines
migrate_irqs() too. It would be great if we could consolidate
all these.
And as we are going to refine these code, there's another
issue need attention. On x86, we need to allocate a CPU vector
if an irq is directed to a CPU. So there's possibility that
we run out of CPU vectors after CPU hot-removal. So we have a
mechanism to detect whether we will run out of CPU vector
after removing a CPU, and reject CPU hot-removal if that will
happen.
So the key point is, if we a need to allocate some sort
of resource on the target CPUs for an irq, we need two steps
when removing a CPU
1) check whether resources are available after removing the CPU,
and reject CPU removal request if we ran out of resource
2) fix irqs after hot-removing the CPU.
Thanks!
Gerry
>
> Cc: Jiang Liu <jiang.liu at linux.intel.com>
> Cc: Thomas Gleixner <tglx at linutronix.de>
> Cc: Marc Zyngier <marc.zyngier at arm.com>
> Cc: Mark Rutland <mark.rutland at arm.com>
> Cc: Will Deacon <will.deacon at arm.com>
> Cc: Russell King - ARM Linux <linux at arm.linux.org.uk>
> Cc: Hanjun Guo <hanjun.guo at linaro.org>
>
> Yang Yingliang (4):
> genirq: Introduce irq_settings_set_move_pcntxt() helper
> irqchip: GICv3: set non-percpu irqs status with _IRQ_MOVE_PCNTXT
> genirq: rename config GENERIC_PENDING_IRQ to GENERIC_IRQ_MIGRATION
> arm/arm64: fix a migrating irq bug when hotplug cpu
>
> arch/arc/Kconfig | 2 +-
> arch/arm/Kconfig | 1 +
> arch/arm/include/asm/irq.h | 1 -
> arch/arm/kernel/irq.c | 62 ------------------------------------------
> arch/arm64/Kconfig | 1 +
> arch/arm64/include/asm/irq.h | 1 -
> arch/arm64/kernel/irq.c | 62 ------------------------------------------
> arch/hexagon/Kconfig | 2 +-
> arch/ia64/Kconfig | 2 +-
> arch/tile/Kconfig | 2 +-
> arch/x86/Kconfig | 2 +-
> arch/x86/kernel/apic/io_apic.c | 2 +-
> drivers/irqchip/irq-gic-v3.c | 2 ++
> include/linux/irq.h | 5 +++-
> include/linux/irqdesc.h | 2 +-
> kernel/irq/Kconfig | 4 +--
> kernel/irq/Makefile | 2 +-
> kernel/irq/irqdesc.c | 18 ++++++++++--
> kernel/irq/manage.c | 2 +-
> kernel/irq/migration.c | 62 ++++++++++++++++++++++++++++++++++++++++++
> kernel/irq/proc.c | 2 +-
> kernel/irq/settings.h | 5 ++++
> 22 files changed, 102 insertions(+), 142 deletions(-)
>
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