Blackfin: SMP: disable preempt with smp_processor_id to send messages

The smp_processor_id() API requires that preempt be disabled when calling
it, so make sure it is when we go to send messages to other processors.
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/mach-common/smp.c

@@ -244,13 +244,14 @@ int smp_call_function(void (*func)(void *info), void *info, int wait)
 {
 	cpumask_t callmap;
 
+	preempt_disable();
 	callmap = cpu_online_map;
 	cpu_clear(smp_processor_id(), callmap);
-	if (cpus_empty(callmap))
-		return 0;
-
+	if (!cpus_empty(callmap))
 		smp_send_message(callmap, BFIN_IPI_CALL_FUNC, func, info, wait);
 
+	preempt_enable();
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(smp_call_function);
@@ -286,13 +287,14 @@ void smp_send_stop(void)
 {
 	cpumask_t callmap;
 
+	preempt_disable();
 	callmap = cpu_online_map;
 	cpu_clear(smp_processor_id(), callmap);
-	if (cpus_empty(callmap))
-		return;
-
+	if (!cpus_empty(callmap))
 		smp_send_message(callmap, BFIN_IPI_CPU_STOP, NULL, NULL, 0);
 
+	preempt_enable();
+
 	return;
 }