score: Move NULL pointer check to order function

This helps to avoid untestable code for the normal SMP schedulers.

2 files changed, 30 insertions, 17 deletions

diff --git a/cpukit/score/include/rtems/score/schedulersmpimpl.h b/cpukit/score/include/rtems/score/schedulersmpimpl.h
index ee81955f8c..b4126b5d6d 100644
--- a/cpukit/score/include/rtems/score/schedulersmpimpl.h
+++ b/cpukit/score/include/rtems/score/schedulersmpimpl.h
@@ -471,7 +471,9 @@ static inline Thread_Control *_Scheduler_SMP_Get_lowest_scheduled(
  * @param[in] move_from_scheduled_to_ready Function to move a node from the set
  *   of scheduled nodes to the set of ready nodes.
  * @param[in] get_lowest_scheduled Function to select the thread from the
- *   scheduled nodes to replace. It may not be possible to find one.
+ *   scheduled nodes to replace.  It may not be possible to find one, in this
+ *   case a pointer must be returned so that the order functions returns false
+ *   if this pointer is passed as the second argument to the order function.
  * @param[in] allocate_processor Function to allocate a processor to a thread
  *   based on the rules of the scheduler.
  */
@@ -490,20 +492,7 @@ static inline void _Scheduler_SMP_Enqueue_ordered(
   Thread_Control *lowest_scheduled =
     ( *get_lowest_scheduled )( context, thread, order );
 
-  /*
-   *  get_lowest_scheduled can return a NULL if no scheduled threads
-   *  should be removed from their processor based on the selection
-   *  criteria. For example, this can occur when the affinity of the
-   *  thread being enqueued schedules it against higher priority threads.
-   *  A low priority thread with affinity can only consider the threads
-   *  which are on the cores if has affinity for.
-   *
-   *  The get_lowest_scheduled helper should assert on not returning NULL
-   *  if that is not possible for that scheduler.
-   */
-
-  if ( lowest_scheduled &&
-       ( *order )( &thread->Object.Node, &lowest_scheduled->Object.Node ) ) {
+  if ( ( *order )( &thread->Object.Node, &lowest_scheduled->Object.Node ) ) {
     Scheduler_SMP_Node *lowest_scheduled_node =
       _Scheduler_SMP_Node_get( lowest_scheduled );
 
diff --git a/cpukit/score/src/schedulerpriorityaffinitysmp.c b/cpukit/score/src/schedulerpriorityaffinitysmp.c
index 6677126688..f5ab8cf158 100644
--- a/cpukit/score/src/schedulerpriorityaffinitysmp.c
+++ b/cpukit/score/src/schedulerpriorityaffinitysmp.c
@@ -42,6 +42,30 @@
  *  + _Scheduler_priority_SMP_Do_update
  */
 
+static bool _Scheduler_priority_affinity_SMP_Insert_priority_lifo_order(
+  const Chain_Node *to_insert,
+  const Chain_Node *next
+)
+{
+  const Thread_Control *thread_to_insert = (const Thread_Control *) to_insert;
+  const Thread_Control *thread_next = (const Thread_Control *) next;
+
+  return next != NULL
+    && thread_to_insert->current_priority <= thread_next->current_priority;
+}
+
+static bool _Scheduler_priority_affinity_SMP_Insert_priority_fifo_order(
+  const Chain_Node *to_insert,
+  const Chain_Node *next
+)
+{
+  const Thread_Control *thread_to_insert = (const Thread_Control *) to_insert;
+  const Thread_Control *thread_next = (const Thread_Control *) next;
+
+  return next != NULL
+    && thread_to_insert->current_priority < thread_next->current_priority;
+}
+
 /*
  * This method returns the scheduler node for the specified thread
  * as a scheduler specific type.
@@ -268,7 +292,7 @@ static void _Scheduler_priority_affinity_SMP_Enqueue_fifo(
   _Scheduler_SMP_Enqueue_ordered(
     context,
     thread,
-    _Scheduler_simple_Insert_priority_fifo_order,
+    _Scheduler_priority_affinity_SMP_Insert_priority_fifo_order,
     _Scheduler_priority_SMP_Insert_ready_fifo,
     _Scheduler_SMP_Insert_scheduled_fifo,
     _Scheduler_priority_SMP_Move_from_scheduled_to_ready,
@@ -402,7 +426,7 @@ static void _Scheduler_priority_affinity_SMP_Enqueue_lifo(
   _Scheduler_priority_affinity_SMP_Enqueue_ordered(
     context,
     thread,
-    _Scheduler_simple_Insert_priority_lifo_order,
+    _Scheduler_priority_affinity_SMP_Insert_priority_lifo_order,
     _Scheduler_priority_SMP_Insert_ready_lifo,
     _Scheduler_SMP_Insert_scheduled_lifo
   );