Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull irq fix from Thomas Gleixner:
 "A single bugfix for the irq core to prevent silent data corruption and
  malfunction of threaded interrupts under certain conditions"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq: Make force irq threading setup more robust

Author: torvalds

kernel/irq/manage.c

@@ -1068,14 +1068,21 @@ static int irq_setup_forced_threading(struct irqaction *new)
 	if (new->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT))
 		return 0;
 
+	/*
+	 * No further action required for interrupts which are requested as
+	 * threaded interrupts already
+	 */
+	if (new->handler == irq_default_primary_handler)
+		return 0;
+
 	new->flags |= IRQF_ONESHOT;
 
 	/*
 	 * Handle the case where we have a real primary handler and a
 	 * thread handler. We force thread them as well by creating a
 	 * secondary action.
 	 */
-	if (new->handler != irq_default_primary_handler && new->thread_fn) {
+	if (new->handler && new->thread_fn) {
 		/* Allocate the secondary action */
 		new->secondary = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
 		if (!new->secondary)