linux_dsm_epyc7002/kernel/irq
Thomas Gleixner 01f8fa4f01 genirq: Allow forcing cpu affinity of interrupts
The current implementation of irq_set_affinity() refuses rightfully to
route an interrupt to an offline cpu.

But there is a special case, where this is actually desired. Some of
the ARM SoCs have per cpu timers which require setting the affinity
during cpu startup where the cpu is not yet in the online mask.

If we can't do that, then the local timer interrupt for the about to
become online cpu is routed to some random online cpu.

The developers of the affected machines tried to work around that
issue, but that results in a massive mess in that timer code.

We have a yet unused argument in the set_affinity callbacks of the irq
chips, which I added back then for a similar reason. It was never
required so it got not used. But I'm happy that I never removed it.

That allows us to implement a sane handling of the above scenario. So
the affected SoC drivers can add the required force handling to their
interrupt chip, switch the timer code to irq_force_affinity() and
things just work.

This does not affect any existing user of irq_set_affinity().

Tagged for stable to allow a simple fix of the affected SoC clock
event drivers.

Reported-and-tested-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Tomasz Figa <t.figa@samsung.com>,
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: linux-arm-kernel@lists.infradead.org,
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20140416143315.717251504@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-04-17 23:36:27 +02:00
..
autoprobe.c genirq: Handle pending irqs in irq_startup() 2012-02-15 11:56:59 +01:00
chip.c genirq: Add a new IRQCHIP_EOI_THREADED flag 2014-03-14 13:43:33 +01:00
debug.h irq: hide debug macros so they don't collide with others. 2012-04-23 12:30:03 -04:00
devres.c genirq: Add devm_request_any_context_irq() 2014-02-09 15:27:21 +01:00
dummychip.c genirq: Export dummy_irq_chip 2012-08-21 16:14:23 +02:00
generic-chip.c Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-07-13 15:37:30 -07:00
handle.c genirq: Export symbol no_action() 2014-03-22 11:33:09 +01:00
internals.h genirq: Add a new IRQCHIP_EOI_THREADED flag 2014-03-14 13:43:33 +01:00
irqdesc.c genirq: Add a kstat helper to increment irq stats 2014-03-04 17:37:53 +01:00
irqdomain.c genirq: Include missing header file in irqdomain.c 2014-02-27 13:29:35 +01:00
Kconfig genirq: Generic irq chip requires IRQ_DOMAIN 2014-02-05 10:17:32 +01:00
Makefile irq: add irq_domain translation infrastructure 2011-07-28 01:32:04 -06:00
manage.c genirq: Allow forcing cpu affinity of interrupts 2014-04-17 23:36:27 +02:00
migration.c genirq: Introduce irq_do_set_affinity() to reduce duplicated code 2012-05-24 22:36:40 +02:00
pm.c irq: Enable all irqs unconditionally in irq_resume 2013-11-25 22:20:02 +01:00
proc.c genirq: procfs: Make smp_affinity values go+r 2014-03-19 12:34:29 +01:00
resend.c genirq: Provide means to retrigger parent 2012-11-01 12:11:31 +01:00
settings.h genirq: Prevent spurious detection for unconditionally polled interrupts 2013-11-13 16:03:02 +01:00
spurious.c genirq: Prevent spurious detection for unconditionally polled interrupts 2013-11-13 16:03:02 +01:00