From: Andrew Morton <akpm@linux-foundation.org>

It's supposed to return -EBUSY when asked to execute the callback on the
current CPU.

Cc: Andi Kleen <ak@suse.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/x86_64/kernel/smp.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff -puN arch/x86_64/kernel/smp.c~x86_64-fix-smp_call_function_single-return-value arch/x86_64/kernel/smp.c
--- a/arch/x86_64/kernel/smp.c~x86_64-fix-smp_call_function_single-return-value
+++ a/arch/x86_64/kernel/smp.c
@@ -363,7 +363,7 @@ __smp_call_function_single(int cpu, void
  * @nonatomic: Currently unused.
  * @wait: If true, wait until function has completed on other CPUs.
  *
- * Retrurns 0 on success, else a negative status code.
+ * Returns 0 on success, else a negative status code.
  *
  * Does not return until the remote CPU is nearly ready to execute <func>
  * or is or has executed.
@@ -376,7 +376,7 @@ int smp_call_function_single (int cpu, v
 	int me = get_cpu();
 	if (cpu == me) {
 		put_cpu();
-		return 0;
+		return -EBUSY;
 	}
 
 	/* Can deadlock when called with interrupts disabled */
_