linux.git/include/linux/irq.h, branch v4.14-rc4

Revert "genirq: Restrict effective affinity to interrupts actually using it"

2017-09-21T09:54:44+00:00

This reverts commit 74def747bcd09692bdbf8c6a15350795b0f11ca8.

The change to the helper function is only correct for the /proc/irq/
readout usage, but breaks the existing x86 usage of that function.

Reported-by: Yanko Kaneti 
Signed-off-by: Thomas Gleixner 
Cc: Marc Zyngier

Merge branch 'irq/for-gpio' into irq/core

2017-08-18T09:22:27+00:00

Merge the flow handlers and irq domain extensions which are in a separate
branch so they can be consumed by the gpio folks.

genirq: Add handle_fasteoi_{level,edge}_irq flow handlers

2017-08-18T09:21:41+00:00

Follow-on patch for gpio-thunderx uses a irqdomain hierarchy which
requires slightly different flow handlers, add them to chip.c which
contains most of the other flow handlers.  Make these conditionally
compiled based on CONFIG_IRQ_FASTEOI_HIERARCHY_HANDLERS.

Signed-off-by: David Daney 
Signed-off-by: Thomas Gleixner 
Cc: Mark Rutland 
Cc: Alexandre Courbot 
Cc: Marc Zyngier 
Cc: Linus Walleij 
Cc: linux-gpio@vger.kernel.org
Link: http://lkml.kernel.org/r/1503017616-3252-3-git-send-email-david.daney@cavium.com

genirq: Restrict effective affinity to interrupts actually using it

2017-08-18T08:54:39+00:00

Just because CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK is selected
doesn't mean that all the interrupts are using the effective
affinity mask. For a number of them, this mask is likely to
be empty.

In order to deal with this, let's restrict the use of the
effective affinity mask to these interrupts that have a non empty
effective affinity.

Signed-off-by: Marc Zyngier 
Signed-off-by: Thomas Gleixner 
Cc: Andrew Lunn 
Cc: James Hogan 
Cc: Jason Cooper 
Cc: Paul Burton 
Cc: Chris Zankel 
Cc: Kevin Cernekee 
Cc: Wei Xu 
Cc: Max Filippov 
Cc: Florian Fainelli 
Cc: Gregory Clement 
Cc: Matt Redfearn 
Cc: Sebastian Hesselbarth 
Link: http://lkml.kernel.org/r/20170818083925.10108-2-marc.zyngier@arm.com

genirq/cpuhotplug: Revert "Set force affinity flag on hotplug migration"

2017-07-27T13:40:02+00:00

That commit was part of the changes moving x86 to the generic CPU hotplug
interrupt migration code. The force flag was required on x86 before the
hierarchical irqdomain rework, but invoking set_affinity() with force=true
stayed and had no side effects.

At some point in the past, the force flag got repurposed to support the
exynos timer interrupt affinity setting to a not yet online CPU, so the
interrupt controller callback does not verify the supplied affinity mask
against cpu_online_mask.

Setting the flag in the CPU hotplug code causes the cpu online masking to
be blocked on these irq controllers and results in potentially affining an
interrupt to the CPU which is unplugged, i.e. instead of moving it away,
it's just reassigned to it.

As the force flags is not longer needed on x86, it's safe to revert that
patch so the ARM irqchips which use the force flag work again.

Add comments to that effect, so this won't happen again.

Note: The online mask handling should be done in the generic code and the
force flag and the masking in the irq chips removed all together, but
that's not a change possible for 4.13. 

Fixes: 77f85e66aa8b ("genirq/cpuhotplug: Set force affinity flag on hotplug migration")
Reported-by: Will Deacon 
Signed-off-by: Thomas Gleixner 
Acked-by: Will Deacon 
Cc: Marc Zyngier 
Cc: Russell King 
Cc: LAK 
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1707271217590.3109@nanos
Signed-off-by: Thomas Gleixner

genirq: Introduce IRQD_SINGLE_TARGET flag

2017-06-22T16:21:25+00:00

Many interrupt chips allow only a single CPU as interrupt target. The core
code has no knowledge about that. That's unfortunate as it could avoid
trying to readd a newly online CPU to the effective affinity mask.

Add the status flag and the necessary accessors.

Signed-off-by: Thomas Gleixner 
Cc: Jens Axboe 
Cc: Marc Zyngier 
Cc: Michael Ellerman 
Cc: Keith Busch 
Cc: Peter Zijlstra 
Cc: Christoph Hellwig 
Link: http://lkml.kernel.org/r/20170619235447.352343969@linutronix.de

genirq/cpuhotplug: Handle managed IRQs on CPU hotplug

2017-06-22T16:21:25+00:00

If a CPU goes offline, interrupts affine to the CPU are moved away. If the
outgoing CPU is the last CPU in the affinity mask the migration code breaks
the affinity and sets it it all online cpus.

This is a problem for affinity managed interrupts as CPU hotplug is often
used for power management purposes. If the affinity is broken, the
interrupt is not longer affine to the CPUs to which it was allocated.

The affinity spreading allows to lay out multi queue devices in a way that
they are assigned to a single CPU or a group of CPUs. If the last CPU goes
offline, then the queue is not longer used, so the interrupt can be
shutdown gracefully and parked until one of the assigned CPUs comes online
again.

Add a graceful shutdown mechanism into the irq affinity breaking code path,
mark the irq as MANAGED_SHUTDOWN and leave the affinity mask unmodified.

In the online path, scan the active interrupts for managed interrupts and
if the interrupt is functional and the newly online CPU is part of the
affinity mask, restart the interrupt if it is marked MANAGED_SHUTDOWN or if
the interrupts is started up, try to add the CPU back to the effective
affinity mask.

Originally-by: Christoph Hellwig 
Signed-off-by: Thomas Gleixner 
Cc: Jens Axboe 
Cc: Marc Zyngier 
Cc: Michael Ellerman 
Cc: Keith Busch 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20170619235447.273417334@linutronix.de

genirq: Handle managed irqs gracefully in irq_startup()

2017-06-22T16:21:24+00:00

Affinity managed interrupts should keep their assigned affinity accross CPU
hotplug. To avoid magic hackery in device drivers, the core code shall
manage them transparently and set these interrupts into a managed shutdown
state when the last CPU of the assigned affinity mask goes offline. The
interrupt will be restarted when one of the CPUs in the assigned affinity
mask comes back online.

Add the necessary logic to irq_startup(). If an interrupt is requested and
started up, the code checks whether it is affinity managed and if so, it
checks whether a CPU in the interrupts affinity mask is online. If not, it
puts the interrupt into managed shutdown state. 

Signed-off-by: Thomas Gleixner 
Cc: Jens Axboe 
Cc: Marc Zyngier 
Cc: Michael Ellerman 
Cc: Keith Busch 
Cc: Peter Zijlstra 
Cc: Christoph Hellwig 
Link: http://lkml.kernel.org/r/20170619235447.189851170@linutronix.de

genirq: Introduce IRQD_MANAGED_SHUTDOWN

2017-06-22T16:21:23+00:00

Affinity managed interrupts should keep their assigned affinity accross CPU
hotplug. To avoid magic hackery in device drivers, the core code shall
manage them transparently. This will set these interrupts into a managed
shutdown state when the last CPU of the assigned affinity mask goes
offline. The interrupt will be restarted when one of the CPUs in the
assigned affinity mask comes back online.

Introduce the necessary state flag and the accessor functions.

Signed-off-by: Thomas Gleixner 
Cc: Jens Axboe 
Cc: Marc Zyngier 
Cc: Michael Ellerman 
Cc: Keith Busch 
Cc: Peter Zijlstra 
Cc: Christoph Hellwig 
Link: http://lkml.kernel.org/r/20170619235446.954523476@linutronix.de

genirq: Introduce effective affinity mask

2017-06-22T16:21:20+00:00

There is currently no way to evaluate the effective affinity mask of a
given interrupt. Many irq chips allow only a single target CPU or a subset
of CPUs in the affinity mask.

Updating the mask at the time of setting the affinity to the subset would
be counterproductive because information for cpu hotplug about assigned
interrupt affinities gets lost. On CPU hotplug it's also pointless to force
migrate an interrupt, which is not targeted at the CPU effectively. But
currently the information is not available.

Provide a seperate mask to be updated by the irq_chip->irq_set_affinity()
implementations. Implement the read only proc files so the user can see the
effective mask as well w/o trying to deduce it from /proc/interrupts.

Signed-off-by: Thomas Gleixner 
Cc: Jens Axboe 
Cc: Marc Zyngier 
Cc: Michael Ellerman 
Cc: Keith Busch 
Cc: Peter Zijlstra 
Cc: Christoph Hellwig 
Link: http://lkml.kernel.org/r/20170619235446.247834245@linutronix.de