From: Daniel Kiper <dkiper@net-space.pl>
Date: Thu, 19 Aug 2010 22:46:16 +0000 (+0200)
Subject: x86, apic: Fix apic=debug boot crash
X-Git-Tag: firefly_0821_release~10186^2~1100
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=f3889381304788cab273a8f78a51b5b596429360;p=firefly-linux-kernel-4.4.55.git

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>
---

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;