From f3889381304788cab273a8f78a51b5b596429360 Mon Sep 17 00:00:00 2001
From: Daniel Kiper <dkiper@net-space.pl>
Date: Fri, 20 Aug 2010 00:46:16 +0200
Subject: [PATCH] x86, apic: Fix apic=debug boot crash

commit 05e407603e527f9d808dd3866d3a17c2ce4dfcc5 upstream.

Fix a boot crash when apic=debug is used and the APIC is
not properly initialized.

This issue appears during Xen Dom0 kernel boot but the
fix is generic and the crash could occur on real hardware
as well.

Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
Cc: xen-devel@lists.xensource.com
Cc: konrad.wilk@oracle.com
Cc: jeremy@goop.org
LKML-Reference: <20100819224616.GB9967@router-fw-old.local.net-space.pl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 arch/x86/kernel/apic/io_apic.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 9f9fdedc5eb3..1acd1c451638 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1736,6 +1736,8 @@ __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;
-- 
2.34.1