From d6de85e85edcc38c9edcde45a0a568818fcddc13 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 3 May 2012 12:22:06 +0200
Subject: [PATCH] gpio: mpc8xxx: Prevent NULL pointer deref in demux handler

commit cfadd838(powerpc/8xxx: Fix interrupt handling in MPC8xxx GPIO
driver) added an unconditional call of chip->irq_eoi() to the demux
handler.

This leads to a NULL pointer derefernce on MPC512x platforms which use
this driver as well.

Make it conditional.

Reported-by: Thomas Wucher <thwucher@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Felix Radensky <felix@embedded-sol.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: stable@vger.kernel.org
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---
 drivers/gpio/gpio-mpc8xxx.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-mpc8xxx.c b/drivers/gpio/gpio-mpc8xxx.c
index e6568c19c939e1..5a1817eedd1ba4 100644
--- a/drivers/gpio/gpio-mpc8xxx.c
+++ b/drivers/gpio/gpio-mpc8xxx.c
@@ -163,7 +163,8 @@ static void mpc8xxx_gpio_irq_cascade(unsigned int irq, struct irq_desc *desc)
 	if (mask)
 		generic_handle_irq(irq_linear_revmap(mpc8xxx_gc->irq,
 						     32 - ffs(mask)));
-	chip->irq_eoi(&desc->irq_data);
+	if (chip->irq_eoi)
+		chip->irq_eoi(&desc->irq_data);
 }
 
 static void mpc8xxx_irq_unmask(struct irq_data *d)