score: add Inherited_priorities priority queue and functions

Adds enqueue, dequeue, requeue, evaluate, and release functions
for the thread priority node priority queue of inherited priorities.
Add calls to these functions as needed to maintain the priority
queue due to blocking, unblocking, and priority changes.

Closes #3359.

2 files changed, 61 insertions, 4 deletions

diff --git a/cpukit/score/include/rtems/score/coremutex.h b/cpukit/score/include/rtems/score/coremutex.h
index ba2ae02782..25d6f488e4 100644
--- a/cpukit/score/include/rtems/score/coremutex.h
+++ b/cpukit/score/include/rtems/score/coremutex.h
@@ -216,7 +216,7 @@ typedef struct {
  *
  *  The following defines the control block used to manage each mutex.
  */
-typedef struct {
+typedef struct CORE_mutex_Control {
   /** This field is the Waiting Queue used to manage the set of tasks
    *  which are blocked waiting to lock the mutex.
    */
diff --git a/cpukit/score/include/rtems/score/thread.h b/cpukit/score/include/rtems/score/thread.h
index b0b40f713c..4c51977106 100644
--- a/cpukit/score/include/rtems/score/thread.h
+++ b/cpukit/score/include/rtems/score/thread.h
@@ -276,15 +276,23 @@ typedef struct {
   Thread_queue_Control *queue;
 }   Thread_Wait_information;
 
+struct CORE_mutex_Control;
 /**
  * @brief Encapsulates base and inherited priority.
  */
 typedef struct Thread_Priority_node {
-  Chain_Node               Node;
+  Chain_Node                   Node;
   /** current priority = min(real_priority, min(Inherited_priorities)) */
-  Priority_Control         current_priority;
+  Priority_Control             current_priority;
   /** base priority irrespective of inheritance/ceiling */
-  Priority_Control         real_priority;
+  Priority_Control             real_priority;
+  /** NULL if not waiting, or the mutex blocked upon
+   * if waiting. If not NULL, then this Priority_node is on the mutex holder's
+   * Priority_node.Inherited_priorities list. */
+  struct CORE_mutex_Control   *waiting_to_hold;
+  /** Priority Queue of thread Priority_nodes blocked by this one, thus
+   * possibly contributing their priority to the current_priority. */
+  Chain_Control                Inherited_priorities;
 } Thread_Priority_node;
 
 /**
@@ -787,6 +795,55 @@ void _Thread_Resume(
  */
 bool _Thread_Evaluate_mode( void );
 
+/**
+ * This routine sets the thread's priority_node->current_priority to the
+ * minimum of the real_priority and the first node of Inherited_priorities,
+ * if any.
+ */
+void _Thread_Evaluate_priority(
+  Thread_Control *the_thread
+);
+
+/**
+ * This routine adds a thread's Priority_node to the mutex holder's
+ * Inherited_priorities list, and sets the waiting_to_hold field to the
+ * mutex.
+ *
+ * Returns true if the enqueued node is at the head of the holder's
+ * Inherited priorities, and therefore the holder's priority may change.
+ */
+bool _Thread_Enqueue_priority_node(
+  Thread_Control *the_thread,
+  struct CORE_mutex_Control *the_mutex
+);
+
+/**
+ * This routine removes a thread's Priority_node from an
+ * Inherited_priorities list, updates the mutex holder's
+ * current_priority if needed, and clears the mutex field.
+ *
+ * Returns the mutex that the thread was waiting on.
+ */
+struct CORE_mutex_Control* _Thread_Dequeue_priority_node(
+  Thread_Priority_node *thread_pn
+);
+
+/**
+ * This routine updates the position of a thread's Priority_node in an
+ * Inherited_priorities list if on one.
+ */
+void _Thread_Requeue_priority_node(
+  Thread_Control *the_thread
+);
+
+/**
+ * This routine removes the inherited priorities from the mutex being
+ * released and updates the holder's priority if necessary.
+ */
+void _Thread_Release_inherited_priority(
+  struct CORE_mutex_Control *the_mutex
+);
+
 #if (CPU_PROVIDES_IDLE_THREAD_BODY == FALSE)
 /**
  *  This routine is the body of the system idle thread.