When initiating I/O on a multiqueue and multi-IRQ device, we may want
to select a queue for which the response will be handled on the same
or a nearby CPU. This requires a reverse-map of IRQ affinity. Add a
notification mechanism to support this.
This is based closely on work by Thomas Gleixner <tglx@linutronix.de>.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
---
include/linux/interrupt.h | 41 +++++++++++++++++++++++
include/linux/irqdesc.h | 3 ++
kernel/irq/manage.c | 81 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 125 insertions(+), 0 deletions(-)
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 55e0d42..09d6039 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -14,6 +14,8 @@
#include <linux/smp.h>
#include <linux/percpu.h>
#include <linux/hrtimer.h>
+#include <linux/kref.h>
+#include <linux/workqueue.h>
#include <asm/atomic.h>
#include <asm/ptrace.h>
@@ -231,6 +233,28 @@ static inline void resume_device_irqs(void) { };
static inline int check_wakeup_irqs(void) { return 0; }
#endif
+/**
+ * struct irq_affinity_notify - context for notification of IRQ affinity changes
+ * @irq: Interrupt to which notification applies
+ * @kref: Reference count, for internal use
+ * @work: Work item, for internal use
+ * @notify: Function to be called on change. This will be
+ * called in process context.
+ * @release: Function to be called on release. This will be
+ * called in process context. Once registered, the
+ * structure must only be freed when this function is
+ * called or later.
+ */
+struct irq_affinity_notify {
+ unsigned int irq;
+ struct kref kref;
+#if defined(CONFIG_SMP) && defined(CONFIG_GENERIC_HARDIRQS)
+ struct work_struct work;
+#endif
+ void (*notify)(struct irq_affinity_notify *, const cpumask_t *mask);
+ void (*release)(struct kref *ref);
+};
+
#if defined(CONFIG_SMP) && ...
