[PATCH] genirq: Avoid NULL OOPS in irq handling

[Huacai Chen <chenhc@lemote.com>]

Some devices (e.g. serial port) setup irq handler at dev open and free
it at dev close. So, sometimes there is no irqaction for a specific
irq. But some buggy devices may send irqs at any time. This patch avoid
the NULL OOPS when irqaction isn't registered.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
---
 kernel/irq/handle.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 131ca17..1c78e69 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -135,6 +135,9 @@ handle_irq_event_percpu(struct irq_desc *desc, struct irqaction *action)
 	irqreturn_t retval = IRQ_NONE;
 	unsigned int flags = 0, irq = desc->irq_data.irq;
 
+	if (!action)
+		goto out;
+
 	do {
 		irqreturn_t res;
 
@@ -174,6 +177,7 @@ handle_irq_event_percpu(struct irq_desc *desc, struct irqaction *action)
 
 	add_interrupt_randomness(irq, flags);
 
+out:
 	if (!noirqdebug)
 		note_interrupt(irq, desc, retval);
 	return retval;
-- 
1.7.7.3