[tip:x86/apic] x86/apic: Fix UP boot crash

[tip-bot for Ingo Molnar <mingo@kernel.org>]

Commit-ID:  9438ef7f4ea73d5430a330fc206f97826eb9fb16
Gitweb:     http://git.kernel.org/tip/9438ef7f4ea73d5430a330fc206f97826eb9fb16
Author:     Ingo Molnar <mingo@kernel.org>
AuthorDate: Mon, 7 May 2012 19:19:56 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 7 May 2012 19:19:56 +0200

x86/apic: Fix UP boot crash

Commit 31b3c9d72340 ("xen/x86: Implement x86_apic_ops") implemented
this:

... without considering that on UP the function pointer might be NULL.

Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Link: http://lkml.kernel.org/n/tip-3pfty0ml4yp62phbkchichh0@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/setup.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 8526317..7e67c5a 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1012,7 +1012,8 @@ void __init setup_arch(char **cmdline_p)
 	init_cpu_to_node();
 
 	init_apic_mappings();
-	x86_io_apic_ops.init();
+	if (x86_io_apic_ops.init)
+		x86_io_apic_ops.init();
 
 	kvm_guest_init();