score: Add _SMP_Need_inter_processor_interrupts()

Test for the proper system condition instead of using the
rtems_configuration_is_smp_enabled() workaround.

Update #3876.

cpukit/include/rtems/score/smpimpl.h

@@ -324,6 +324,21 @@ RTEMS_INLINE_ROUTINE const Processor_mask *_SMP_Get_online_processors( void )
 #endif
 }
 
+/**
+ * @brief Indicate if inter-processor interrupts are needed.
+ *
+ * @return True if inter-processor interrupts are needed for the correct system
+ * operation, otherwise false.
+ */
+RTEMS_INLINE_ROUTINE const bool _SMP_Need_inter_processor_interrupts( void )
+{
+  /*
+   * Use the configured processor maximum instead of the actual to allow
+   * testing on uni-processor systems.
+   */
+  return _SMP_Processor_configured_maximum > 1;
+}
+
 /** @} */
 
 #ifdef __cplusplus

cpukit/rtems/src/taskmode.c

@@ -23,6 +23,7 @@
 #include <rtems/rtems/modesimpl.h>
 #include <rtems/rtems/signalimpl.h>
 #include <rtems/score/schedulerimpl.h>
+#include <rtems/score/smpimpl.h>
 #include <rtems/score/threadimpl.h>
 #include <rtems/config.h>
 
@@ -58,7 +59,7 @@ rtems_status_code rtems_task_mode(
     ( mask & RTEMS_INTERRUPT_MASK ) != 0
       && _Modes_Get_interrupt_level( mode_set ) != 0
 #if CPU_ENABLE_ROBUST_THREAD_DISPATCH == FALSE
-      && rtems_configuration_is_smp_enabled()
+      && _SMP_Need_inter_processor_interrupts()
 #endif
   ) {
     return RTEMS_NOT_IMPLEMENTED;

cpukit/score/src/threaddispatch.c

@@ -265,7 +265,7 @@ void _Thread_Do_dispatch( Per_CPU_Control *cpu_self, ISR_Level level )
   if (
     !_ISR_Is_enabled( level )
 #if defined(RTEMS_SMP) && CPU_ENABLE_ROBUST_THREAD_DISPATCH == FALSE
-      && rtems_configuration_is_smp_enabled()
+      && _SMP_Need_inter_processor_interrupts()
 #endif
   ) {
     _Internal_error( INTERNAL_ERROR_BAD_THREAD_DISPATCH_ENVIRONMENT );

cpukit/score/src/threadinitialize.c

@@ -72,7 +72,7 @@ bool _Thread_Initialize(
   if (
     config->isr_level != 0
 #if CPU_ENABLE_ROBUST_THREAD_DISPATCH == FALSE
-      && rtems_configuration_is_smp_enabled()
+      && _SMP_Need_inter_processor_interrupts()
 #endif
   ) {
     goto failed;