x86/apic: Fix UP boot crash

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

---
 arch/x86/kernel/setup.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

index 8526317..7e67c5a 100644
@@ -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();