genirq: fix handle_nested_irq for lazy disable

When lazy disabling is implemented and an interrupt is disabled the
genirq code ends up marking it as IRQ_DISABLED in the descriptor.
The interrupt stays enabled in the controller.  If the interrupt
fires after disabling, the flow handlers namely handle_level_irq and
handle_edge_irq mask the interrupt in the controller.

This is not the case with handle_nested_irq. The interrupt stays enabled in
the controller and if it were a level interrupt it keeps firing only to be
ignored by handle_nested_irq.

Update handle_nested_irq to mask such an interrupt.

CRs-Fixed: 300931
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>

Conflicts:

	kernel/irq/chip.c
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index d5a3009..dc154f2 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -244,6 +244,7 @@
 {
 	struct irq_desc *desc = irq_to_desc(irq);
 	struct irqaction *action;
+	int mask_this_irq = 0;
 	irqreturn_t action_ret;
 
 	might_sleep();
@@ -253,8 +254,10 @@
 	kstat_incr_irqs_this_cpu(irq, desc);
 
 	action = desc->action;
-	if (unlikely(!action || irqd_irq_disabled(&desc->irq_data)))
+	if (unlikely(!action || irqd_irq_disabled(&desc->irq_data))) {
+		mask_this_irq = 1;
 		goto out_unlock;
+	}
 
 	irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS);
 	raw_spin_unlock_irq(&desc->lock);
@@ -268,6 +271,11 @@
 
 out_unlock:
 	raw_spin_unlock_irq(&desc->lock);
+	if (unlikely(mask_this_irq)) {
+		chip_bus_lock(desc);
+		mask_irq(desc);
+		chip_bus_sync_unlock(desc);
+	}
 }
 EXPORT_SYMBOL_GPL(handle_nested_irq);