[PATCH] gpio: langwell: Prevent possible NULL pointer dereference in the demux handler.

[Krzysztof Wilczynski]

This is to address a possible NULL pointer dereference on a platform that might
use this driver but its underlying IRQ chip does not provide an irq_eoi callback.

A commit 0766d20 added an conditional to the code, but then it was later
super-seeded by commit 20e2aa9 which introduced number of helper functions
for accessing various members of the irq_desc struct, but removed said
conditional from the code.

This change will re-introduce conditional guarding against possible NULL
pointer dereference caused by missing EIO handler.

Signed-off-by: Krzysztof Wilczynski <krzysztof.wilczynski@xxxxxxxxx>
---
 drivers/gpio/gpio-langwell.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/gpio/gpio-langwell.c b/drivers/gpio/gpio-langwell.c
index 00692e8..5749738 100644
--- a/drivers/gpio/gpio-langwell.c
+++ b/drivers/gpio/gpio-langwell.c
@@ -260,7 +260,8 @@ static void lnw_irq_handler(unsigned irq, struct irq_desc *desc)
 		}
 	}
 
-	chip->irq_eoi(data);
+	if (data)
+		chip->irq_eoi(data);
 }
 
 #ifdef CONFIG_PM
-- 
1.7.2.5

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