kernel.git/kernel/irq/cpuhotplug.c, branch linux-4.13.y

genirq/cpuhotplug: Add sanity check for effective affinity mask

2017-10-18T07:38:31Z

commit 60b09c51bb4fb46e2331fdbb39f91520f31d35f7 upstream. The effective affinity mask handling has no safety net when the mask is not updated by the interrupt chip or the mask contains offline CPUs. If that happens the CPU unplug code fails to migrate interrupts. Add sanity checks and emit a warning when the mask contains only offline CPUs. Fixes: 415fcf1a2293 ("genirq/cpuhotplug: Use effective affinity mask") Signed-off-by: Thomas Gleixner Cc: Marc Zyngier Cc: Christoph Hellwig Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1710042208400.2406@nanos Signed-off-by: Greg Kroah-Hartman

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

2017-07-27T13:40:02Z

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/cpuhotplug: Avoid irq affinity setting for single targets

2017-06-22T16:21:25Z

Avoid trying to add a newly online CPU to the effective affinity mask of an started up interrupt. That interrupt will either stay on the already online CPU or move around for no value. 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/20170619235447.431321047@linutronix.de

genirq/cpuhotplug: Handle managed IRQs on CPU hotplug

2017-06-22T16:21:25Z

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/cpuhotplug: Use effective affinity mask

2017-06-22T16:21:21Z

If the architecture supports the effective affinity mask, migrating interrupts away which are not targeted by the effective mask is pointless. They can stay in the user or system supplied affinity mask, but won't be targetted at any given point as the affinity setter functions need to validate against the online cpu mask anyway. 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/20170619235446.328488490@linutronix.de

genirq/cpuhotplug: Set force affinity flag on hotplug migration

2017-06-22T16:21:18Z

Set the force migration flag when migrating interrupts away from an outgoing CPU. 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/20170619235445.681874648@linutronix.de

genirq/cpuhotplug: Add support for conditional masking

2017-06-22T16:21:17Z

Interrupts which cannot be migrated in process context, need to be masked before the affinity is changed forcefully. Add support for that. Will be compiled out for architectures which do not have this x86 specific issue. 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/20170619235445.604565591@linutronix.de

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

2017-06-22T16:21:17Z

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/cpuhotplug: Do not migrated shutdown irqs

2017-06-22T16:21:17Z

Interrupts, which are shut down are tried to be migrated as well. That's pointless because the interrupt cannot fire and the next startup will move it to the proper place anyway. 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/20170619235445.447550992@linutronix.de

genirq/cpuhotplug: Reorder check logic

2017-06-22T16:21:16Z

Move the checks for a valid irq chip and the irq_set_affinity() callback right in front of the whole migration logic. No point in doing a gazillion of other things when the interrupt cannot be migrated at all. 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/20170619235445.354181630@linutronix.de