score: Need for help indicator for scheduler ops

Return a thread in need for help for the following scheduler operations

- unblock,
- change priority, and
- yield.

A thread in need for help is a thread that encounters a scheduler state
change from scheduled to ready or a thread that cannot be scheduled in
an unblock operation.  Such a thread can ask threads which depend on
resources owned by this thread for help.

1 files changed, 31 insertions, 18 deletions

diff --git a/cpukit/score/src/schedulerpriorityaffinitysmp.c b/cpukit/score/src/schedulerpriorityaffinitysmp.c
index e6a662e361..14a022e5d7 100644
--- a/cpukit/score/src/schedulerpriorityaffinitysmp.c
+++ b/cpukit/score/src/schedulerpriorityaffinitysmp.c
@@ -288,14 +288,16 @@ static Scheduler_Node * _Scheduler_priority_affinity_SMP_Get_lowest_scheduled(
  * _Scheduler_priority_affinity_SMP_Get_lowest_scheduled into
  * _Scheduler_SMP_Enqueue_ordered.
  */
-static void _Scheduler_priority_affinity_SMP_Enqueue_fifo(
+static Thread_Control *_Scheduler_priority_affinity_SMP_Enqueue_fifo(
   Scheduler_Context *context,
-  Scheduler_Node    *node
+  Scheduler_Node    *node,
+  Thread_Control    *needs_help
 )
 {
-  _Scheduler_SMP_Enqueue_ordered(
+  return _Scheduler_SMP_Enqueue_ordered(
     context,
     node,
+    needs_help,
     _Scheduler_priority_affinity_SMP_Insert_priority_fifo_order,
     _Scheduler_priority_SMP_Insert_ready_fifo,
     _Scheduler_SMP_Insert_scheduled_fifo,
@@ -374,14 +376,15 @@ static void _Scheduler_priority_affinity_SMP_Check_for_migrations(
 /*
  * This is the public scheduler specific Unblock operation.
  */
-void _Scheduler_priority_affinity_SMP_Unblock(
+Thread_Control *_Scheduler_priority_affinity_SMP_Unblock(
   const Scheduler_Control *scheduler,
   Thread_Control *thread
 )
 {
   Scheduler_Context *context = _Scheduler_Get_context( scheduler );
+  Thread_Control    *needs_help;
 
-  _Scheduler_SMP_Unblock(
+  needs_help = _Scheduler_SMP_Unblock(
     context,
     thread,
     _Scheduler_priority_affinity_SMP_Enqueue_fifo
@@ -391,23 +394,27 @@ void _Scheduler_priority_affinity_SMP_Unblock(
    * Perform any thread migrations that are needed due to these changes.
    */
   _Scheduler_priority_affinity_SMP_Check_for_migrations( context );
+
+  return needs_help;
 }
 
 /*
  *  This is unique to this scheduler because it passes scheduler specific
  *  get_lowest_scheduled helper to _Scheduler_SMP_Enqueue_ordered.
  */
-static void _Scheduler_priority_affinity_SMP_Enqueue_ordered(
+static Thread_Control *_Scheduler_priority_affinity_SMP_Enqueue_ordered(
   Scheduler_Context     *context,
   Scheduler_Node        *node,
+  Thread_Control        *needs_help,
   Chain_Node_order       order,
   Scheduler_SMP_Insert   insert_ready,
   Scheduler_SMP_Insert   insert_scheduled
 )
 {
-  _Scheduler_SMP_Enqueue_ordered(
+  return _Scheduler_SMP_Enqueue_ordered(
     context,
     node,
+    needs_help,
     order,
     insert_ready,
     insert_scheduled,
@@ -422,14 +429,16 @@ static void _Scheduler_priority_affinity_SMP_Enqueue_ordered(
  *  to _Scheduler_priority_affinity_SMP_Enqueue_ordered() which
  *  invokes a scheduler unique get_lowest_scheduled helper.
  */
-static void _Scheduler_priority_affinity_SMP_Enqueue_lifo(
+static Thread_Control *_Scheduler_priority_affinity_SMP_Enqueue_lifo(
   Scheduler_Context *context,
-  Scheduler_Node    *node
+  Scheduler_Node    *node,
+  Thread_Control    *needs_help
 )
 {
-  _Scheduler_priority_affinity_SMP_Enqueue_ordered(
+  return _Scheduler_priority_affinity_SMP_Enqueue_ordered(
     context,
     node,
+    needs_help,
     _Scheduler_priority_affinity_SMP_Insert_priority_lifo_order,
     _Scheduler_priority_SMP_Insert_ready_lifo,
     _Scheduler_SMP_Insert_scheduled_lifo
@@ -441,7 +450,8 @@ static void _Scheduler_priority_affinity_SMP_Enqueue_lifo(
  * invoke _Scheduler_SMP_Enqueue_scheduled_ordered() with
  * this scheduler's get_highest_ready() helper.
  */
-static void _Scheduler_priority_affinity_SMP_Enqueue_scheduled_ordered(
+static Thread_Control *
+_Scheduler_priority_affinity_SMP_Enqueue_scheduled_ordered(
   Scheduler_Context    *context,
   Scheduler_Node       *node,
   Chain_Node_order      order,
@@ -449,7 +459,7 @@ static void _Scheduler_priority_affinity_SMP_Enqueue_scheduled_ordered(
   Scheduler_SMP_Insert  insert_scheduled
 )
 {
-  _Scheduler_SMP_Enqueue_scheduled_ordered(
+  return _Scheduler_SMP_Enqueue_scheduled_ordered(
     context,
     node,
     order,
@@ -466,12 +476,12 @@ static void _Scheduler_priority_affinity_SMP_Enqueue_scheduled_ordered(
  *  to _Scheduler_priority_affinity_SMP_Enqueue_scheduled__ordered() which
  *  invokes a scheduler unique get_lowest_scheduled helper.
  */
-static void _Scheduler_priority_affinity_SMP_Enqueue_scheduled_lifo(
+static Thread_Control *_Scheduler_priority_affinity_SMP_Enqueue_scheduled_lifo(
   Scheduler_Context *context,
   Scheduler_Node    *node
 )
 {
-  _Scheduler_priority_affinity_SMP_Enqueue_scheduled_ordered(
+  return _Scheduler_priority_affinity_SMP_Enqueue_scheduled_ordered(
     context,
     node,
     _Scheduler_SMP_Insert_priority_lifo_order,
@@ -485,12 +495,12 @@ static void _Scheduler_priority_affinity_SMP_Enqueue_scheduled_lifo(
  *  to _Scheduler_priority_affinity_SMP_Enqueue_scheduled__ordered() which
  *  invokes a scheduler unique get_lowest_scheduled helper.
  */
-static void _Scheduler_priority_affinity_SMP_Enqueue_scheduled_fifo(
+static Thread_Control *_Scheduler_priority_affinity_SMP_Enqueue_scheduled_fifo(
   Scheduler_Context *context,
   Scheduler_Node    *node
 )
 {
-  _Scheduler_priority_affinity_SMP_Enqueue_scheduled_ordered(
+  return _Scheduler_priority_affinity_SMP_Enqueue_scheduled_ordered(
     context,
     node,
     _Scheduler_SMP_Insert_priority_fifo_order,
@@ -502,7 +512,7 @@ static void _Scheduler_priority_affinity_SMP_Enqueue_scheduled_fifo(
 /*
  * This is the public scheduler specific Change Priority operation.
  */
-void _Scheduler_priority_affinity_SMP_Change_priority(
+Thread_Control *_Scheduler_priority_affinity_SMP_Change_priority(
   const Scheduler_Control *scheduler,
   Thread_Control          *thread,
   Priority_Control         new_priority,
@@ -510,8 +520,9 @@ void _Scheduler_priority_affinity_SMP_Change_priority(
 )
 {
   Scheduler_Context *context = _Scheduler_Get_context( scheduler );
+  Thread_Control    *displaced;
 
-  _Scheduler_SMP_Change_priority(
+  displaced = _Scheduler_SMP_Change_priority(
     context,
     thread,
     new_priority,
@@ -528,6 +539,8 @@ void _Scheduler_priority_affinity_SMP_Change_priority(
    * Perform any thread migrations that are needed due to these changes.
    */
   _Scheduler_priority_affinity_SMP_Check_for_migrations( context );
+
+  return displaced;
 }
 
 /*