[PATCH] x86_64: fix async IPIs

Fix async IPI to not return before stack data is used.
This can fix reboot crashes and apparently helps vmware.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/x86_64/kernel/smp.c

@@ -305,13 +305,13 @@ static void __smp_call_function (void (*func) (void *info), void *info,
 	/* Send a message to all other CPUs and wait for them to respond */
 	send_IPI_allbutself(CALL_FUNCTION_VECTOR);
 
-	if (!wait)
-		return;
-
 	/* Wait for response */
 	while (atomic_read(&data.started) != cpus)
 		cpu_relax();
 
+	if (!wait)
+		return;
+
 	while (atomic_read(&data.finished) != cpus)
 		cpu_relax();
 }