lwn.git/include/linux/irq.h, branch standardize-docs

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

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: Provide irq_fixup_move_pending()

2017-06-22T16:21:13+00:00

If an CPU goes offline, the interrupts are migrated away, but a eventually pending interrupt move, which has not yet been made effective is kept pending even if the outgoing CPU is the sole target of the pending affinity mask. What's worse is, that the pending affinity mask is discarded even if it would contain a valid subset of the online CPUs. Implement a helper function which allows to avoid these issues. 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/20170619235444.691345468@linutronix.de

genirq: Add missing comment for IRQD_STARTED

2017-06-22T16:21:13+00:00

Signed-off-by: Thomas Gleixner Cc: Marc Zyngier Cc: Jens Axboe Cc: Michael Ellerman Cc: Keith Busch Cc: Peter Zijlstra Cc: Christoph Hellwig Link: http://lkml.kernel.org/r/20170619235444.614913014@linutronix.de

irq/generic-chip: Provide devm_irq_setup_generic_chip()

2017-06-21T13:53:11+00:00

Provide a resource managed variant of irq_setup_generic_chip(). Signed-off-by: Bartosz Golaszewski Signed-off-by: Thomas Gleixner Acked-by: Marc Zyngier Cc: linux-doc@vger.kernel.org Cc: Jonathan Corbet Link: http://lkml.kernel.org/r/1496246820-13250-6-git-send-email-brgl@bgdev.pl