linux-stable.git/kernel/irq/internals.h, branch linux-4.13.y

genirq/PM: Properly pretend disabled state when force resuming interrupts

2017-07-17T20:32:20+00:00

Interrupts with the IRQF_FORCE_RESUME flag set have also the
IRQF_NO_SUSPEND flag set. They are not disabled in the suspend path, but
must be forcefully resumed. That's used by XEN to keep IPIs enabled beyond
the suspension of device irqs. Force resume works by pretending that the
interrupt was disabled and then calling __irq_enable().

Incrementing the disabled depth counter was enough to do that, but with the
recent changes which use state flags to avoid unnecessary hardware access,
this is not longer sufficient. If the state flags are not set, then the
hardware callbacks are not invoked and the interrupt line stays disabled in
"hardware".

Set the disabled and masked state when pretending that an interrupt got
disabled by suspend.

Fixes: bf22ff45bed6 ("genirq: Avoid unnecessary low level irq function calls")
Suggested-by: Thomas Gleixner 
Signed-off-by: Juergen Gross 
Signed-off-by: Thomas Gleixner 
Cc: xen-devel@lists.xenproject.org
Cc: boris.ostrovsky@oracle.com
Link: http://lkml.kernel.org/r/20170717174703.4603-2-jgross@suse.com

genirq/debugfs: Fix build for !CONFIG_IRQ_DOMAIN

2017-07-04T10:36:43+00:00

Fix this build error:

kernel/irq/internals.h:440:20: error: inlining failed in call to always_inline
  'irq_domain_debugfs_init': function body not available
kernel/irq/debugfs.c:202:2: note: called from here
  irq_domain_debugfs_init(root_dir);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Sebastian Ott 
Signed-off-by: Thomas Gleixner 
Link: http://lkml.kernel.org/r/alpine.LFD.2.20.1707041124000.1712@schleppi

genirq/timings: Add infrastructure for estimating the next interrupt arrival time

2017-06-24T09:44:39+00:00

An interrupt behaves with a burst of activity with periodic interval of time
followed by one or two peaks of longer interval.

As the time intervals are periodic, statistically speaking they follow a normal
distribution and each interrupts can be tracked individually.

Add a mechanism to compute the statistics on all interrupts, except the
timers which are deterministic from a prediction point of view, as their
expiry time is known.

The goal is to extract the periodicity for each interrupt, with the last
timestamp and sum them, so the next event can be predicted to a certain
extent.

Taking the earliest prediction gives the expected wakeup on the system
(assuming a timer won't expire before).

Signed-off-by: Daniel Lezcano 
Signed-off-by: Thomas Gleixner 
Cc: Nicolas Pitre 
Cc: Jens Axboe 
Cc: Hannes Reinecke 
Cc: Vincent Guittot 
Cc: "Rafael J . Wysocki" 
Cc: Peter Zijlstra 
Cc: Bjorn Helgaas 
Link: http://lkml.kernel.org/r/1498227072-5980-2-git-send-email-daniel.lezcano@linaro.org

genirq/timings: Add infrastructure to track the interrupt timings

2017-06-24T09:44:11+00:00

The interrupt framework gives a lot of information about each interrupt. It
does not keep track of when those interrupts occur though, which is a
prerequisite for estimating the next interrupt arrival for power management
purposes.

Add a mechanism to record the timestamp for each interrupt occurrences in a
per-CPU circular buffer to help with the prediction of the next occurrence
using a statistical model.

Each CPU can store up to IRQ_TIMINGS_SIZE events , the
current value of IRQ_TIMINGS_SIZE is 32.

Each event is encoded into a single u64, where the high 48 bits are used
for the timestamp and the low 16 bits are for the irq number.

A static key is introduced so when the irq prediction is switched off at
runtime, the overhead is near to zero.

It results in most of the code in internals.h for inline reasons and a very
few in the new file timings.c. The latter will contain more in the next patch
which will provide the statistical model for the next event prediction.

Signed-off-by: Daniel Lezcano 
Signed-off-by: Thomas Gleixner 
Acked-by: Nicolas Pitre 
Cc: Jens Axboe 
Cc: Hannes Reinecke 
Cc: Vincent Guittot 
Cc: "Rafael J . Wysocki" 
Cc: Peter Zijlstra 
Cc: Bjorn Helgaas 
Link: http://lkml.kernel.org/r/1498227072-5980-1-git-send-email-daniel.lezcano@linaro.org

genirq/debugfs: Remove pointless NULL pointer check

2017-06-24T09:43:53+00:00

debugfs_remove() has it's own NULL pointer check. Remove the conditional
and make irq_remove_debugfs_entry() an inline helper

Reported-by: kbuild test robot 
Signed-off-by: Thomas Gleixner

genirq: Add force argument to irq_startup()

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

In order to handle managed interrupts gracefully on irq_startup() so they
won't lose their assigned affinity, it's necessary to allow startups which
keep the interrupts in managed shutdown state, if none of the assigend CPUs
is online. This allows drivers to request interrupts w/o the CPUs being
online, which avoid online/offline churn in drivers.

Add a force argument which can override that decision and let only
request_irq() and enable_irq() allow the managed shutdown
handling. enable_irq() is required, because the interrupt might be
requested with IRQF_NOAUTOEN and enable_irq() invokes irq_startup() which
would then wreckage the assignment again. All other callers force startup
and potentially break the assigned affinity.

No functional change as this only adds the function argument.

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/20170619235447.112094565@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: Move irq_fixup_move_pending() to core

2017-06-22T16:21:19+00:00

Now that x86 uses the generic code, the function declaration and inline
stub can move to the core internal header.

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/20170619235445.928156166@linutronix.de

genirq/cpuhotplug: Add support for cleaning up move in progress

2017-06-22T16:21:17+00:00

In order to move x86 to the generic hotplug migration code, add support for
cleaning up move in progress bits.

On architectures which have this x86 specific (mis)feature not enabled,
this is optimized out by the compiler.

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/20170619235445.525817311@linutronix.de

genirq: Move pending helpers to internal.h

2017-06-22T16:21:15+00:00

So that the affinity code can reuse them.


Signed-off-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/20170619235445.109426284@linutronix.de