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Subject[PATCH 2/5] genirq: Allow the affinity of a percpu interrupt to be set/retrieved
Date
In order to prepare the genirq layer for the concept of partitionned
percpu interrupts, let's allow an affinity to be associated with
such an interrupt. We introduce:

- irq_set_percpu_devid_partition: flag an interrupt as a percpu-devid
interrupt, and associate it with an affinity
- irq_get_percpu_devid_partition: allow the affinity of that interrupt
to be retrieved.

This will allow a driver to discover which CPUs the per-cpu interrupt
can actually fire on.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
include/linux/irq.h | 4 ++++
include/linux/irqdesc.h | 1 +
kernel/irq/irqdesc.c | 26 +++++++++++++++++++++++++-
3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index c4de623..4d758a7 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -530,6 +530,10 @@ static inline void irq_set_chip_and_handler(unsigned int irq, struct irq_chip *c
}

extern int irq_set_percpu_devid(unsigned int irq);
+extern int irq_set_percpu_devid_partition(unsigned int irq,
+ const struct cpumask *affinity);
+extern int irq_get_percpu_devid_partition(unsigned int irq,
+ struct cpumask *affinity);

extern void
__irq_set_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index dcca77c..b51beeb 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -66,6 +66,7 @@ struct irq_desc {
int threads_handled_last;
raw_spinlock_t lock;
struct cpumask *percpu_enabled;
+ const struct cpumask *percpu_affinity;
#ifdef CONFIG_SMP
const struct cpumask *affinity_hint;
struct irq_affinity_notify *affinity_notify;
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 0ccd028..8731e1c 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -595,7 +595,8 @@ void __irq_put_desc_unlock(struct irq_desc *desc, unsigned long flags, bool bus)
chip_bus_sync_unlock(desc);
}

-int irq_set_percpu_devid(unsigned int irq)
+int irq_set_percpu_devid_partition(unsigned int irq,
+ const struct cpumask *affinity)
{
struct irq_desc *desc = irq_to_desc(irq);

@@ -610,10 +611,33 @@ int irq_set_percpu_devid(unsigned int irq)
if (!desc->percpu_enabled)
return -ENOMEM;

+ if (affinity)
+ desc->percpu_affinity = affinity;
+ else
+ desc->percpu_affinity = cpu_possible_mask;
+
irq_set_percpu_devid_flags(irq);
return 0;
}

+int irq_set_percpu_devid(unsigned int irq)
+{
+ return irq_set_percpu_devid_partition(irq, NULL);
+}
+
+int irq_get_percpu_devid_partition(unsigned int irq, struct cpumask *affinity)
+{
+ struct irq_desc *desc = irq_to_desc(irq);
+
+ if (!desc || !desc->percpu_enabled)
+ return -EINVAL;
+
+ if (affinity)
+ cpumask_copy(affinity, desc->percpu_affinity);
+
+ return 0;
+}
+
void kstat_incr_irq_this_cpu(unsigned int irq)
{
kstat_incr_irqs_this_cpu(irq_to_desc(irq));
--
2.1.4
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