genirq: Add IRQ affinity notifiers

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>
Cc: linux-net-drivers@solarflare.com
Cc: Tom Herbert <therbert@google.com>
Cc: David Miller <davem@davemloft.net>
LKML-Reference: <1295470904.11126.84.camel@bwh-desktop>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index c1a95b7b58de..bfef56dadddb 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -8,6 +8,7 @@
  * For now it's included from <linux/irq.h>
  */
 
+struct irq_affinity_notify;
 struct proc_dir_entry;
 struct timer_rand_state;
 /**
@@ -24,6 +25,7 @@ struct timer_rand_state;
  * @last_unhandled:     aging timer for unhandled count
  * @irqs_unhandled:     stats field for spurious unhandled interrupts
  * @lock:               locking for SMP
+ * @affinity_notify:    context for notification of affinity changes
  * @pending_mask:       pending rebalanced interrupts
  * @threads_active:     number of irqaction threads currently running
  * @wait_for_threads:   wait queue for sync_irq to wait for threaded handlers
@@ -70,6 +72,7 @@ struct irq_desc {
         raw_spinlock_t          lock;
 #ifdef CONFIG_SMP
         const struct cpumask    *affinity_hint;
+        struct irq_affinity_notify *affinity_notify;
 #ifdef CONFIG_GENERIC_PENDING_IRQ
         cpumask_var_t           pending_mask;
 #endif