path: root/include/linux/irq.h
diff options
authorThomas Gleixner <tglx@linutronix.de>2017-06-20 01:37:51 +0200
committerThomas Gleixner <tglx@linutronix.de>2017-06-22 18:21:25 +0200
commitc5cb83bb337c25caae995d992d1cdf9b317f83de (patch)
treead779ff06d57ac629b00fd097a6c93c8b0b6141e /include/linux/irq.h
parent761ea388e8c4e3ac883a94e16bcc8c51fa419d4f (diff)
genirq/cpuhotplug: Handle managed IRQs on CPU hotplug
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 <hch@lst.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Jens Axboe <axboe@kernel.dk> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Keith Busch <keith.busch@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20170619235447.273417334@linutronix.de
Diffstat (limited to 'include/linux/irq.h')
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 807042b46af1..19cea6326599 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -500,7 +500,12 @@ extern int irq_set_affinity_locked(struct irq_data *data,
const struct cpumask *cpumask, bool force);
extern int irq_set_vcpu_affinity(unsigned int irq, void *vcpu_info);
extern void irq_migrate_all_off_this_cpu(void);
+extern int irq_affinity_online_cpu(unsigned int cpu);
+# define irq_affinity_online_cpu NULL
void irq_move_irq(struct irq_data *data);