[PATCH] arch/x86/kernel/apic/io_apic.c: Fix for crash when apic=debug is used

[Daniel Kiper]

Hi,

Here is the patch fixing crash when apic=debug
is used and APIC is not properly initialized.
This issue appears during Xen Dom0 kernel boot
(git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git,
xen/stable-2.6.32.x head), however I think that
patch is rather generic and should be applied
to mainline kernel (it applies to Linux Kernel
Ver. 2.6.35 and Ver. 2.6.32.19 with small fuzz).

Daniel

Signed-off-by: Daniel Kiper <dkiper@xxxxxxxxxxxx>
---
 arch/x86/kernel/apic/io_apic.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index e41ed24..2b18af1 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1728,6 +1728,8 @@ __apicdebuginit(void) print_IO_APIC(void)
 		struct irq_pin_list *entry;
 
 		cfg = desc->chip_data;
+		if (!cfg)
+			continue;
 		entry = cfg->irq_2_pin;
 		if (!entry)
 			continue;
--
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