Re: [PATCH] Fix NULL pointer for Xen guests

From: Prarit Bhargava
Date: Wed Apr 28 2010 - 14:29:42 EST




On 04/28/2010 02:26 PM, Andrew Morton wrote:
On Tue, 27 Apr 2010 11:24:42 -0400
Prarit Bhargava<prarit@xxxxxxxxxx> wrote:

Upstream PV guests fail to boot because of a NULL pointer. It is possible that
xen guests have irq_desc->chip_data = NULL.

Test for NULL chip_data pointer before attempting to complete an irq move.

Signed-off-by: Prarit Bhargava<prarit@xxxxxxxxxx>
Acked-by: Suresh Siddha<suresh.b.siddha@xxxxxxxxx>

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 127b871..eb2789c 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2545,6 +2545,9 @@ void irq_force_complete_move(int irq)
struct irq_desc *desc = irq_to_desc(irq);
struct irq_cfg *cfg = desc->chip_data;

+ if (!cfg)
+ return;
+
__irq_complete_move(&desc, cfg->vector);
}
#else
I assume this is needed for 2.6.34?

What about 2.6.33.x and earlier?

Hey Andrew,

I actually pinged Chris Wright to see about including this in the -stable branches. I haven't heard anything back so I'll reping him.

P.
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