[PATCH] genirq: check chip->ack before calling

From: Wang Chen
Date: Mon Dec 29 2008 - 00:35:11 EST


Impact: fix theoretical NULL dereference

The generic irq layer doesn't know whether irq_chip has ack routine on some
architectures or not. Upon that, before calling chip->ack, we should check
that it's not NULL.

Signed-off-by: Wang Chen <wangchen@xxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/irq/chip.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 6eb3c79..0ad02d7 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -290,7 +290,8 @@ static inline void mask_ack_irq(struct irq_desc *desc, int irq)
desc->chip->mask_ack(irq);
else {
desc->chip->mask(irq);
- desc->chip->ack(irq);
+ if (desc->chip->ack)
+ desc->chip->ack(irq);
}
}

@@ -475,7 +476,8 @@ handle_edge_irq(unsigned int irq, struct irq_desc *desc)
kstat_incr_irqs_this_cpu(irq, desc);

/* Start handling the irq */
- desc->chip->ack(irq);
+ if (desc->chip->ack)
+ desc->chip->ack(irq);
desc = irq_remap_to_desc(irq, desc);

/* Mark the IRQ currently in progress.*/

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