[PATCH 8/8] score: Rework thread priority management

Gedare Bloom gedare at rtems.org
Wed Sep 7 18:52:42 UTC 2016


On Tue, Sep 6, 2016 at 8:40 AM, Sebastian Huber
<sebastian.huber at embedded-brains.de> wrote:
> Add priority nodes which contribute to the overall thread priority.
>
> The actual priority of a thread is now an aggregation of priority nodes.
> The thread priority aggregation for the home scheduler instance of a
> thread consists of at least one priority node, which is normally the
> real priority of the thread.  The locking protocols (e.g. priority
> ceiling and priority inheritance), rate-monotonic period objects and the
> POSIX sporadic server add, change and remove priority nodes.
>
> A thread changes its priority now immediately, e.g. priority changes are
> not deferred until the thread releases its last resource.
>
> Replace the _Thread_Change_priority() function with
>
>  * _Thread_Priority_perform_actions(),
>  * _Thread_Priority_add(),
>  * _Thread_Priority_remove(),
>  * _Thread_Priority_change(), and
>  * _Thread_Priority_update().
>
> Update #2412.
> Update #2556.
> ---
>  cpukit/libmisc/capture/capture.h                   |   2 +-
>  cpukit/libmisc/cpuuse/cpuusagetop.c                |   6 +-
>  cpukit/posix/include/rtems/posix/pthreadimpl.h     |   2 +
>  cpukit/posix/include/rtems/posix/threadsup.h       |   8 +-
>  cpukit/posix/src/killinfo.c                        |   2 +-
>  cpukit/posix/src/mutexsetprioceiling.c             |  13 +-
>  cpukit/posix/src/pthread.c                         | 103 ++-
>  cpukit/posix/src/pthreadcreate.c                   |  32 +-
>  cpukit/posix/src/pthreadgetschedparam.c            |   2 +-
>  cpukit/posix/src/pthreadsetschedparam.c            | 143 ++--
>  cpukit/posix/src/pthreadsetschedprio.c             |  92 +--
>  cpukit/rtems/include/rtems/rtems/ratemon.h         |   6 +
>  cpukit/rtems/src/ratemoncancel.c                   |  12 +-
>  cpukit/rtems/src/ratemoncreate.c                   |   2 +
>  cpukit/rtems/src/ratemonperiod.c                   |  15 +-
>  cpukit/rtems/src/semsetpriority.c                  |  18 +-
>  cpukit/rtems/src/tasksetpriority.c                 |  95 +--
>  cpukit/score/Makefile.am                           |   3 +-
>  cpukit/score/include/rtems/score/coremutex.h       |   4 +-
>  cpukit/score/include/rtems/score/coremuteximpl.h   | 148 ++--
>  cpukit/score/include/rtems/score/mrsp.h            |  12 +-
>  cpukit/score/include/rtems/score/mrspimpl.h        | 255 ++++---
>  cpukit/score/include/rtems/score/priority.h        | 159 +++-
>  cpukit/score/include/rtems/score/priorityimpl.h    | 417 ++++++++++
>  cpukit/score/include/rtems/score/scheduler.h       |  28 +-
>  cpukit/score/include/rtems/score/schedulercbs.h    |  17 +-
>  cpukit/score/include/rtems/score/scheduleredf.h    |  26 +-
>  .../score/include/rtems/score/scheduleredfimpl.h   |  14 +-
>  cpukit/score/include/rtems/score/schedulerimpl.h   |  86 ++-
>  cpukit/score/include/rtems/score/schedulernode.h   |  19 +-
>  .../score/include/rtems/score/schedulernodeimpl.h  |  18 +-
>  .../score/include/rtems/score/schedulersmpimpl.h   |  11 +-
>  cpukit/score/include/rtems/score/thread.h          |  53 +-
>  cpukit/score/include/rtems/score/threadimpl.h      | 261 ++++---
>  cpukit/score/include/rtems/score/threadq.h         |  98 ++-
>  cpukit/score/include/rtems/score/threadqimpl.h     | 145 ++--
>  cpukit/score/preinstall.am                         |   4 +
>  cpukit/score/src/mutex.c                           |  21 +-
>  cpukit/score/src/schedulercbs.c                    |  22 +-
>  cpukit/score/src/schedulercbsnodeinit.c            |   1 +
>  cpukit/score/src/schedulercbsreleasejob.c          |  40 +-
>  cpukit/score/src/schedulercbsunblock.c             |  51 +-
>  cpukit/score/src/schedulerdefaultnodeinit.c        |   4 +-
>  cpukit/score/src/schedulerdefaultreleasejob.c      |  20 +-
>  cpukit/score/src/scheduleredfchangepriority.c      |   8 +-
>  cpukit/score/src/scheduleredfnodeinit.c            |   6 +-
>  cpukit/score/src/scheduleredfreleasejob.c          |  84 +--
>  cpukit/score/src/scheduleredfunblock.c             |   2 +-
>  cpukit/score/src/scheduleredfyield.c               |   2 +-
>  cpukit/score/src/schedulerpriority.c               |   2 +-
>  cpukit/score/src/schedulerprioritysmp.c            |   7 +-
>  cpukit/score/src/schedulersimplesmp.c              |   2 +-
>  cpukit/score/src/schedulerstrongapa.c              |   7 +-
>  cpukit/score/src/thread.c                          |   4 +-
>  cpukit/score/src/threadchangepriority.c            | 362 ++++++---
>  cpukit/score/src/threadinitialize.c                |   7 +-
>  cpukit/score/src/threadmp.c                        |   3 +-
>  cpukit/score/src/threadqenqueue.c                  | 120 +--
>  cpukit/score/src/threadqflush.c                    |   9 +-
>  cpukit/score/src/threadqops.c                      | 839 ++++++++++++++++-----
>  cpukit/score/src/threadrestart.c                   |  61 +-
>  cpukit/score/src/threadsetpriority.c               |  59 --
>  cpukit/score/src/threadtimeout.c                   |   3 +
>  testsuites/smptests/smpmutex01/init.c              |   3 +-
>  testsuites/smptests/smpscheduler03/init.c          |  43 +-
>  testsuites/sptests/spmutex01/init.c                | 141 +++-
>  testsuites/sptests/spsem03/init.c                  |  30 +-
>  testsuites/sptests/spsem03/spsem03.doc             |   4 +-
>  68 files changed, 2790 insertions(+), 1508 deletions(-)
>  create mode 100644 cpukit/score/include/rtems/score/priorityimpl.h
>  delete mode 100644 cpukit/score/src/threadsetpriority.c
>
...
> diff --git a/cpukit/score/include/rtems/score/priority.h b/cpukit/score/include/rtems/score/priority.h
> index 842f017..f53c321 100644
> --- a/cpukit/score/include/rtems/score/priority.h
> +++ b/cpukit/score/include/rtems/score/priority.h
> @@ -1,17 +1,15 @@
>  /**
> - * @file rtems/score/priority.h
> + * @file
>   *
> - * @brief Thread Priority Manipulation Routines
> - *
> - * This include file contains all thread priority manipulation routines.
> - * This Handler provides mechanisms which can be used to
> - * initialize and manipulate thread priorities.
> + * @brief Priority Handler API
>   */
>
>  /*
>   *  COPYRIGHT (c) 1989-2011.
>   *  On-Line Applications Research Corporation (OAR).
>   *
> + *  Copyright (c) 2016 embedded brains GmbH.
> + *
>   *  The license and distribution terms for this file may be
>   *  found in the file LICENSE in this distribution or at
>   *  http://www.rtems.org/license/LICENSE.
> @@ -20,58 +18,153 @@
>  #ifndef _RTEMS_SCORE_PRIORITY_H
>  #define _RTEMS_SCORE_PRIORITY_H
>
> -/**
> - *  @defgroup ScorePriority Priority Handler
> - *
> - *  @ingroup Score
> - *
> - *  This handler encapsulates functionality which is used to manage
> - *  thread priorities.  At the SuperCore level 256 priority levels
> - *  are supported with lower numbers representing logically more important
> - *  threads.  The priority level 0 is reserved for internal RTEMS use.
> - *  Typically it is assigned to threads which defer internal RTEMS
> - *  actions from an interrupt to thread level to improve interrupt response.
> - *  Priority level 255 is assigned to the IDLE thread and really should not
> - *  be used by application threads.  The default IDLE thread implementation
> - *  is an infinite "branch to self" loop which never yields to other threads
> - *  at the same priority.
> - */
> -/**@{*/
> -
> -/*
> - * Processor specific information.
> - */
> +#include <rtems/score/chain.h>
>  #include <rtems/score/cpu.h>
> +#include <rtems/score/rbtree.h>
> +
> +struct Scheduler_Control;
>
>  #ifdef __cplusplus
>  extern "C" {
>  #endif
>
>  /**
> - *  The following type defines the control block used to manage
> - *  thread priorities.
> + * @defgroup ScorePriority Priority Handler
> + *
> + * @ingroup Score
>   *
> - *  @note Priority 0 is reserved for internal threads only.
> + * This handler encapsulates functionality which is used to manage thread
> + * priorities.  The actual priority of a thread is an aggregation of priority
> + * nodes.  The thread priority aggregation for the home scheduler instance of a
> + * thread consists of at least one priority node, which is normally the real
> + * priority of the thread.  The locking protocols (e.g. priority ceiling and
> + * priority inheritance), rate-monotonic period objects and the POSIX sporadic
> + * server add, change and remove priority nodes.
> + *
> + * @{
> + */
> +
> +/**
> + * @brief A plain thread priority value.
> + *
> + * Lower values represent higher priorities.  So, a priority value of zero
> + * represents the highest priority thread.  This value is reserved for internal
> + * threads and the priority ceiling protocol.
>   */
>  typedef uint64_t Priority_Control;
>
> -/** This defines the highest (most important) thread priority. */
> +/**
> + * @brief The highest (most important) thread priority value.
> + */
>  #define PRIORITY_MINIMUM      0
>
>  /**
> - * @brief This defines the priority of pseudo-ISR threads.
> + * @brief The priority value of pseudo-ISR threads.
>   *
>   * Examples are the MPCI and timer server threads.
>   */
>  #define PRIORITY_PSEUDO_ISR   PRIORITY_MINIMUM
>
> -/** This defines the default lowest (least important) thread priority. */
> +/**
> + * @brief The default lowest (least important) thread priority value.
> + *
> + * This value is CPU port dependent.
> + */
>  #if defined (CPU_PRIORITY_MAXIMUM)
>    #define PRIORITY_DEFAULT_MAXIMUM      CPU_PRIORITY_MAXIMUM
>  #else
>    #define PRIORITY_DEFAULT_MAXIMUM      255
>  #endif
>
> +/**
> + * @brief The priority node to build up a priority aggregation.
> + */
> +typedef struct {
> +  /**
> +   * @brief Node component for a chain or red-black tree.
> +   */
> +  union {
> +    Chain_Node Chain;
> +    RBTree_Node RBTree;
> +  } Node;
> +
> +  /**
> +   * @brief The priority value of this node.
> +   */
> +  Priority_Control priority;
> +} Priority_Node;
> +
> +/**
> + * @brief The priority action type.
> + */
> +typedef enum {
> +  PRIORITY_ACTION_ADD,
> +  PRIORITY_ACTION_CHANGE,
> +  PRIORITY_ACTION_REMOVE,
> +  PRIORITY_ACTION_INVALID
> +} Priority_Action_type;
> +
> +typedef struct Priority_Aggregation Priority_Aggregation;
> +
> +/**
> + * @brief The priority aggregation.
> + */
> +struct Priority_Aggregation {
> +  /**
> +   * @brief A priority node reflection the overall priority of the aggregation.
> +   *
reflection -> "reflection of" or maybe "reflects"? Or, "represents"

> +   * May be used to add this aggregation to another aggregation to build up a
> +   * recursive priority scheme.
> +   */
> +  Priority_Node Node;
> +
> +  /**
> +   * @brief A red-black tree to contain priority nodes contributing to the
> +   * overall priority of the this priority aggregation.
"the this" -> "this"

> +   */
> +  RBTree_Control Contributors;
> +
Is it the case that a priority node is only ever on one of these
"Contributors" trees at a time?

> +#if defined(RTEMS_SMP)
> +  /**
> +   * @brief The scheduler instance of this priority aggregation.
> +   */
> +  const struct Scheduler_Control *scheduler;
> +#endif
> +
> +  /**
> +   * @brief A priority action block to manage priority node additions, changes
> +   * and removals.
> +   */
> +  struct {
> +#if defined(RTEMS_SMP)
> +    /**
> +     * @brief The next priority aggregation in the action chain.
> +     */
> +    Priority_Aggregation *next;
> +#endif
> +
> +    /**
> +     * @brief The priority node of the action.
> +     */
> +    Priority_Node *node;
> +
> +    /**
> +     * @brief The type of the action.
> +     */
> +    Priority_Action_type type;
> +  } Action;
> +};
> +
> +/**
> + * @brief A set of priority actions.
> + */
> +typedef struct {
> +  /**
> +   * @brief The first action of a priority action chain.
I would prefer consistently to refer to either actions in the priority
action chain, or priority aggregations in the action chain. It should
be clarified somewhere in the doxygen that a Priority_Aggregation can
be on a singly-linked list of aggregations for (pending?) priority
actions, and also on a red-black tree for recursive priority
dependencies.

It may be a bit confusing to refer to something as a chain that is not
making use of the "RTEMS Chains"

> +   */
> +  Priority_Aggregation *actions;
> +} Priority_Actions;
> +
>  #ifdef __cplusplus
>  }
>  #endif
> diff --git a/cpukit/score/include/rtems/score/priorityimpl.h b/cpukit/score/include/rtems/score/priorityimpl.h
> new file mode 100644
> index 0000000..d022c1f
> --- /dev/null
> +++ b/cpukit/score/include/rtems/score/priorityimpl.h
> @@ -0,0 +1,417 @@
> +/*
> + * Copyright (c) 2016 embedded brains GmbH.  All rights reserved.
> + *
> + *  embedded brains GmbH
> + *  Dornierstr. 4
> + *  82178 Puchheim
> + *  Germany
> + *  <rtems at embedded-brains.de>
> + *
> + * The license and distribution terms for this file may be
> + * found in the file LICENSE in this distribution or at
> + * http://www.rtems.org/license/LICENSE.
> + */
> +
> +#ifndef _RTEMS_SCORE_PRIORITYIMPL_H
> +#define _RTEMS_SCORE_PRIORITYIMPL_H
> +
> +#include <rtems/score/priority.h>
> +#include <rtems/score/scheduler.h>
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif /* __cplusplus */
> +
> +RTEMS_INLINE_ROUTINE void _Priority_Actions_initialize_empty(
> +  Priority_Actions *actions
> +)
> +{
> +  actions->actions = NULL;
> +}
> +
> +RTEMS_INLINE_ROUTINE void _Priority_Actions_initialize_one(
> +  Priority_Actions     *actions,
> +  Priority_Aggregation *aggregation,
> +  Priority_Node        *node,
> +  Priority_Action_type  type
> +)
> +{
> +#if defined(RTEMS_SMP)
> +  aggregation->Action.next = NULL;
> +#endif
> +  aggregation->Action.node = node;
> +  aggregation->Action.type = type;
> +
> +  actions->actions = aggregation;
> +}
> +
> +RTEMS_INLINE_ROUTINE bool _Priority_Actions_is_empty(
> +  const Priority_Actions *actions
> +)
> +{
> +  return actions->actions == NULL;
> +}
> +
> +RTEMS_INLINE_ROUTINE bool _Priority_Actions_is_valid(
> +  const Priority_Aggregation *aggregation
> +)
> +{
> +#if defined(RTEMS_SMP)
> +  return aggregation != NULL;
> +#else
> +  (void) aggregation;
> +  return false;
> +#endif
> +}
> +
> +RTEMS_INLINE_ROUTINE void _Priority_Actions_move(
> +  Priority_Actions *target_actions,
> +  Priority_Actions *source_actions
> +)
> +{
> +  target_actions->actions = source_actions->actions;
> +  source_actions->actions = NULL;
> +}
> +
> +RTEMS_INLINE_ROUTINE Priority_Aggregation *_Priority_Actions_get_first(
> +  const Priority_Actions *actions
> +)
> +{
> +  return actions->actions;
> +}
> +
> +RTEMS_INLINE_ROUTINE void _Priority_Actions_add(
> +  Priority_Actions     *actions,
> +  Priority_Aggregation *aggregation
> +)
> +{
> +#if defined(RTEMS_SMP)
> +  aggregation->Action.next = actions->actions;

Do we not care what was previously in the .next field?

[...]

> diff --git a/cpukit/score/include/rtems/score/threadq.h b/cpukit/score/include/rtems/score/threadq.h
> index a4ad082..058603b 100644
> --- a/cpukit/score/include/rtems/score/threadq.h
> +++ b/cpukit/score/include/rtems/score/threadq.h
> @@ -47,8 +47,6 @@ typedef struct Thread_queue_Queue Thread_queue_Queue;
>
>  typedef struct Thread_queue_Operations Thread_queue_Operations;
>
> -typedef struct Thread_queue_Path Thread_queue_Path;
> -
>  /**
>   * @brief Thread queue deadlock callout.
>   *
> @@ -195,6 +193,45 @@ typedef struct {
>     */
>    uint64_t timeout;
>
> +#if defined(RTEMS_SMP)
> +  /**
> +   * @brief Representation of a thread queue path from a start thread queue to
> +   * the terminal thread queue.
> +   *
> +   * The start thread queue is determined by the object on which a thread intends
> +   * to block.  The terminal thread queue is the thread queue reachable via
> +   * thread queue links those owner is not blocked on a thread queue.  The thread

those -> whose ?

> +   * queue links are determined by the thread queue owner and thread wait queue
> +   * relationships.
> +   */
> +  struct {
> +    /**
> +     * @brief The chain of thread queue links defining the thread queue path.
> +     */
> +    Chain_Control Links;
> +
> +    /**
> +     * @brief The start of a thread queue path.
> +     */
> +    Thread_queue_Link Start;
> +  } Path;
> +#endif
> +
> +  struct {
> +    Priority_Actions Actions;
> +
> +    /**
> +     * @brief Count of threads to update the priority via
> +     * _Thread_Priority_update().
> +     */
> +    size_t update_count;

I'd prefer uint32_t for unsigned counters since usually size_t denotes
an object's (byte) size.

> +
> +    /**
> +     * @brief Threads to update the priority via _Thread_Priority_update().
> +     */
> +    Thread_Control *update[ 2 ];

Why 2?

> +  } Priority;
> +
>    /**
>     * @brief Invoked in case of a detected deadlock.
>     *
> @@ -237,7 +274,7 @@ typedef struct {
>    /**
>     * @brief The actual thread priority queue.
>     */
> -  RBTree_Control Queue;
> +  Priority_Aggregation Queue;
>  } Thread_queue_Priority_queue;
>
>  /**
> @@ -289,6 +326,11 @@ typedef struct _Thread_queue_Heads {
>
>  #if defined(RTEMS_SMP)
>    /**
> +   * @brief Boost priority.

This note could be expanded (e.g. boosted by xxx). Thanks for
improving the doxy along the way!

> +   */
> +  Priority_Node Boost_priority;
> +
> +  /**
>     * @brief One priority queue per scheduler instance.
>     */
>    Thread_queue_Priority_queue Priority[ RTEMS_ZERO_LENGTH_ARRAY ];
> @@ -337,34 +379,33 @@ struct Thread_queue_Queue {
>  };
>
>  /**
> - * @brief Thread queue priority change operation.
> + * @brief Thread queue action operation.
>   *
>   * @param[in] queue The actual thread queue.
>   * @param[in] the_thread The thread.
> - * @param[in] new_priority The new priority value.
> - *
> - * @see Thread_queue_Operations.
> + * @param[in] queue_context The thread queue context providing the thread queue
> + *   action set to perform.  Returns the thread queue action set to perform on
> + *   the thread queue owner or the empty set in case there is nothing to do.
>   */
> -typedef void ( *Thread_queue_Priority_change_operation )(
> -  Thread_queue_Queue *queue,
> -  Thread_Control     *the_thread,
> -  Priority_Control    new_priority
> +typedef void ( *Thread_queue_Priority_actions_operation )(
> +  Thread_queue_Queue   *queue,
> +  Priority_Actions     *priority_actions
>  );
>
>  /**
>   * @brief Thread queue enqueue operation.
>   *
>   * A potential thread to update the priority due to priority inheritance is
> - * returned via the thread queue path.  This thread is handed over to
> - * _Thread_Update_priority().
> + * returned via the thread queue context.  This thread is handed over to
> + * _Thread_Priority_update().
>   *
>   * @param[in] queue The actual thread queue.
>   * @param[in] the_thread The thread to enqueue on the queue.
>   */
>  typedef void ( *Thread_queue_Enqueue_operation )(
> -  Thread_queue_Queue *queue,
> -  Thread_Control     *the_thread,
> -  Thread_queue_Path  *path
> +  Thread_queue_Queue   *queue,
> +  Thread_Control       *the_thread,
> +  Thread_queue_Context *queue_context
>  );
>
>  /**
> @@ -374,8 +415,9 @@ typedef void ( *Thread_queue_Enqueue_operation )(
>   * @param[in] the_thread The thread to extract from the thread queue.
>   */
>  typedef void ( *Thread_queue_Extract_operation )(
> -  Thread_queue_Queue *queue,
> -  Thread_Control     *the_thread
> +  Thread_queue_Queue   *queue,
> +  Thread_Control       *the_thread,
> +  Thread_queue_Context *queue_context
>  );
>
>  /**
> @@ -390,9 +432,10 @@ typedef void ( *Thread_queue_Extract_operation )(
>   * @return The previous first thread on the queue.
>   */
>  typedef Thread_Control *( *Thread_queue_Surrender_operation )(
> -  Thread_queue_Queue *queue,
> -  Thread_queue_Heads *heads,
> -  Thread_Control     *previous_owner
> +  Thread_queue_Queue   *queue,
> +  Thread_queue_Heads   *heads,
> +  Thread_Control       *previous_owner,
> +  Thread_queue_Context *queue_context
>  );
>
>  /**
> @@ -415,16 +458,9 @@ typedef Thread_Control *( *Thread_queue_First_operation )(
>   */
>  struct Thread_queue_Operations {
>    /**
> -   * @brief Thread queue priority change operation.
> -   *
> -   * Called by _Thread_Change_priority() to notify a thread about a priority
> -   * change.  In case this thread waits currently for a resource the handler
> -   * may adjust its data structures according to the new priority value.  This
> -   * handler must not be NULL, instead the default handler
> -   * _Thread_Do_nothing_priority_change() should be used in case nothing needs
> -   * to be done during a priority change.
> -   */
> -  Thread_queue_Priority_change_operation priority_change;
> +   * @brief Thread queue priority actions operation.
This note also should be expanded a bit.

> +   */
> +  Thread_queue_Priority_actions_operation priority_actions;
>
>    /**
>     * @brief Thread queue enqueue operation.
> diff --git a/cpukit/score/include/rtems/score/threadqimpl.h b/cpukit/score/include/rtems/score/threadqimpl.h
> index 977b0ce..3555b7f 100644
> --- a/cpukit/score/include/rtems/score/threadqimpl.h
> +++ b/cpukit/score/include/rtems/score/threadqimpl.h
> @@ -21,7 +21,7 @@
>
>  #include <rtems/score/threadq.h>
>  #include <rtems/score/chainimpl.h>
> -#include <rtems/score/rbtreeimpl.h>
> +#include <rtems/score/priorityimpl.h>
>  #include <rtems/score/scheduler.h>
>  #include <rtems/score/smp.h>
>  #include <rtems/score/thread.h>
> @@ -39,38 +39,8 @@ extern "C" {
>   */
>  /**@{*/
>
> -/**
> - * @brief Representation of a thread queue path from a start thread queue to
> - * the terminal thread queue.
> - *
> - * The start thread queue is determined by the object on which a thread intends
> - * to block.  The terminal thread queue is the thread queue reachable via
> - * thread queue links those owner is not blocked on a thread queue.  The thread
> - * queue links are determined by the thread queue owner and thread wait queue
> - * relationships.
> - */
> -struct Thread_queue_Path {
> -#if defined(RTEMS_SMP)
> -  /**
> -   * @brief The chain of thread queue links defining the thread queue path.
> -   */
> -  Chain_Control Links;
> -
> -  /**
> -   * @brief The start of a thread queue path.
> -   */
> -  Thread_queue_Link Start;
> -#endif
> -
> -  /**
> -   * @brief A potential thread to update the priority via
> -   * _Thread_Update_priority().
> -   *
> -   * This thread is determined by thread queues which support priority
> -   * inheritance.
> -   */
> -  Thread_Control *update_priority;
> -};
> +#define THREAD_QUEUE_LINK_OF_PATH_NODE( node ) \
> +  RTEMS_CONTAINER_OF( node, Thread_queue_Link, Path_node );
>
>  /**
>   * @brief Thread queue with a layout compatible to struct _Thread_queue_Queue
> @@ -210,6 +180,42 @@ RTEMS_INLINE_ROUTINE void _Thread_queue_Context_set_deadlock_callout(
>    queue_context->deadlock_callout = deadlock_callout;
>  }
>
> +RTEMS_INLINE_ROUTINE void _Thread_queue_Context_clear_priority_updates(
> +  Thread_queue_Context *queue_context
> +)
> +{
> +  queue_context->Priority.update_count = 0;
> +}
> +
> +RTEMS_INLINE_ROUTINE size_t _Thread_queue_Context_get_priority_updates(
> +  Thread_queue_Context *queue_context
> +)
> +{
> +  return queue_context->Priority.update_count;
> +}
> +
> +RTEMS_INLINE_ROUTINE void _Thread_queue_Context_set_priority_updates(
> +  Thread_queue_Context *queue_context,
> +  size_t                update_count
> +)
> +{
> +  queue_context->Priority.update_count = update_count;
> +}

Are there some rules for what can/should set the priority updates? Is
this a monotonic counter until clear()?

> +
> +RTEMS_INLINE_ROUTINE void _Thread_queue_Context_add_priority_update(
> +  Thread_queue_Context *queue_context,
> +  Thread_Control       *the_thread
> +)
> +{
> +  size_t n;
> +
> +  n = queue_context->Priority.update_count;
> +  _Assert( n < RTEMS_ARRAY_SIZE( queue_context->Priority.update ) );
> +
> +  queue_context->Priority.update_count = n + 1;

These two assignments could make use of the above _get/set_priority_updates().

> +  queue_context->Priority.update[ n ] = the_thread;
> +}
> +
>  /**
>   * @brief Sets the MP callout in the thread queue context.
>   *
> @@ -274,9 +280,12 @@ RTEMS_INLINE_ROUTINE void _Thread_queue_Heads_initialize(
>  #if defined(RTEMS_SMP)
>    size_t i;
>
> +  _Priority_Node_initialize( &heads->Boost_priority, 0 );
> +  _Priority_Node_set_inactive( &heads->Boost_priority );
> +
>    for ( i = 0; i < _Scheduler_Count; ++i ) {
>      _Chain_Initialize_node( &heads->Priority[ i ].Node );
> -    _RBTree_Initialize_empty( &heads->Priority[ i ].Queue );
> +    _Priority_Initialize_empty( &heads->Priority[ i ].Queue );
>    }
>  #endif
>
> @@ -579,16 +588,6 @@ RTEMS_INLINE_ROUTINE void _Thread_queue_Enqueue(
>    );
>  }
>
> -bool _Thread_queue_Do_extract_locked(
> -  Thread_queue_Queue            *queue,
> -  const Thread_queue_Operations *operations,
> -  Thread_Control                *the_thread
> -#if defined(RTEMS_MULTIPROCESSING)
> -  ,
> -  const Thread_queue_Context    *queue_context
> -#endif
> -);
> -
>  /**
>   * @brief Extracts the thread from the thread queue, restores the default wait
>   * operations and restores the default thread lock.
> @@ -599,8 +598,7 @@ bool _Thread_queue_Do_extract_locked(
>   * @param[in] queue The actual thread queue.
>   * @param[in] operations The thread queue operations.
>   * @param[in] the_thread The thread to extract.
> - * @param[in] queue_context The thread queue context.  This parameter is only
> - *   used on multiprocessing configurations.
> + * @param[in] queue_context The thread queue context.
>   *
>   * @return Returns the unblock indicator for _Thread_queue_Unblock_critical().
>   * True indicates, that this thread must be unblocked by the scheduler later in
> @@ -610,32 +608,12 @@ bool _Thread_queue_Do_extract_locked(
>   * since this thread may already block on another resource in an SMP
>   * configuration.
>   */
> -#if defined(RTEMS_MULTIPROCESSING)
> -  #define _Thread_queue_Extract_locked( \
> -    unblock, \
> -    queue, \
> -    the_thread, \
> -    queue_context \
> -  ) \
> -    _Thread_queue_Do_extract_locked( \
> -      unblock, \
> -      queue, \
> -      the_thread, \
> -      queue_context \
> -    )
> -#else
> -  #define _Thread_queue_Extract_locked( \
> -    unblock, \
> -    queue, \
> -    the_thread, \
> -    queue_context \
> -  ) \
> -    _Thread_queue_Do_extract_locked( \
> -      unblock, \
> -      queue, \
> -      the_thread \
> -    )
> -#endif
> +bool _Thread_queue_Extract_locked(
> +  Thread_queue_Queue            *queue,
> +  const Thread_queue_Operations *operations,
> +  Thread_Control                *the_thread,
> +  const Thread_queue_Context    *queue_context
> +);
>
>  /**
>   * @brief Unblocks the thread which was on the thread queue before.
> @@ -735,7 +713,7 @@ void _Thread_queue_Extract_with_proxy(
>
>  /**
>   * @brief Surrenders the thread queue previously owned by the thread to the
> - * first enqueued thread if it exists.
> + * first enqueued thread.
>   *
>   * The owner of the thread queue must be set to NULL by the caller.
>   *
> @@ -743,21 +721,18 @@ void _Thread_queue_Extract_with_proxy(
>   * thread dispatch if necessary.
>   *
>   * @param[in] queue The actual thread queue.
> - * @param[in] operations The thread queue operations.
> - * @param[in] heads The thread queue heads.
> + * @param[in] heads The thread queue heads.  It must not be NULL.
>   * @param[in] previous_owner The previous owner thread surrendering the thread
>   *   queue.
> - * @param[in] keep_priority Indicates if the previous owner thread should keep
> - *   its current priority.
>   * @param[in] queue_context The thread queue context of the lock acquire.
> + * @param[in] operations The thread queue operations.
>   */
>  void _Thread_queue_Surrender(
>    Thread_queue_Queue            *queue,
> -  const Thread_queue_Operations *operations,
>    Thread_queue_Heads            *heads,
>    Thread_Control                *previous_owner,
> -  bool                           keep_priority,
> -  Thread_queue_Context          *queue_context
> +  Thread_queue_Context          *queue_context,
> +  const Thread_queue_Operations *operations
>  );
>
>  RTEMS_INLINE_ROUTINE bool _Thread_queue_Is_empty(
> @@ -980,6 +955,16 @@ void _Thread_queue_Unblock_proxy(
>  );
>  #endif
>
> +bool _Thread_queue_Path_acquire_critical(
> +  Thread_queue_Queue   *queue,
> +  Thread_Control       *the_thread,
> +  Thread_queue_Context *queue_context
> +);
> +
> +void _Thread_queue_Path_release_critical(
> +  Thread_queue_Context *queue_context
> +);
> +
>  /**
>   * @brief Helper structure to ensure that all objects containing a thread queue
>   * have the right layout.
> diff --git a/cpukit/score/preinstall.am b/cpukit/score/preinstall.am
> index 61d44b8..94865a0 100644
> --- a/cpukit/score/preinstall.am
> +++ b/cpukit/score/preinstall.am
> @@ -200,6 +200,10 @@ $(PROJECT_INCLUDE)/rtems/score/priority.h: include/rtems/score/priority.h $(PROJ
>         $(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/priority.h
>  PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/priority.h
>
> +$(PROJECT_INCLUDE)/rtems/score/priorityimpl.h: include/rtems/score/priorityimpl.h $(PROJECT_INCLUDE)/rtems/score/$(dirstamp)
> +       $(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/priorityimpl.h
> +PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/priorityimpl.h
> +
>  $(PROJECT_INCLUDE)/rtems/score/prioritybitmap.h: include/rtems/score/prioritybitmap.h $(PROJECT_INCLUDE)/rtems/score/$(dirstamp)
>         $(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/prioritybitmap.h
>  PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/prioritybitmap.h
> diff --git a/cpukit/score/src/mutex.c b/cpukit/score/src/mutex.c
> index bfa36ff..daa90a5 100644
> --- a/cpukit/score/src/mutex.c
> +++ b/cpukit/score/src/mutex.c
> @@ -128,33 +128,20 @@ static void _Mutex_Release_critical(
>  )
>  {
>    Thread_queue_Heads *heads;
> -  bool keep_priority;
>
> +  heads = mutex->Queue.Queue.heads;
>    mutex->Queue.Queue.owner = NULL;
> -
>    --executing->resource_count;
>
> -  /*
> -   * Ensure that the owner resource count is visible to all other
> -   * processors and that we read the latest priority restore
> -   * hint.
> -   */
> -  _Atomic_Fence( ATOMIC_ORDER_ACQ_REL );
> -
> -  heads = mutex->Queue.Queue.heads;
> -  keep_priority = _Thread_Owns_resources( executing )
> -    || !executing->priority_restore_hint;
> -
> -  if ( __predict_true( heads == NULL && keep_priority ) ) {
> +  if ( __predict_true( heads == NULL ) ) {
>      _Mutex_Queue_release( mutex, queue_context );
>    } else {
>      _Thread_queue_Surrender(
>        &mutex->Queue.Queue,
> -      MUTEX_TQ_OPERATIONS,
>        heads,
>        executing,
> -      keep_priority,
> -      queue_context
> +      queue_context,
> +      MUTEX_TQ_OPERATIONS
>      );
>    }
>  }
> diff --git a/cpukit/score/src/schedulercbs.c b/cpukit/score/src/schedulercbs.c
> index 98ec0eb..f114d4f 100644
> --- a/cpukit/score/src/schedulercbs.c
> +++ b/cpukit/score/src/schedulercbs.c
> @@ -19,24 +19,28 @@
>  #endif
>
>  #include <rtems/score/schedulercbsimpl.h>
> -#include <rtems/score/threadimpl.h>
> -#include <rtems/score/wkspace.h>
>
>  void _Scheduler_CBS_Budget_callout(
>    Thread_Control *the_thread
>  )
>  {
> -  Priority_Control          new_priority;
> -  Priority_Control          unused;
> -  Scheduler_CBS_Node       *node;
> -  Scheduler_CBS_Server_id   server_id;
> +  Scheduler_CBS_Node      *node;
> +  Scheduler_CBS_Server_id  server_id;
> +  Thread_queue_Context     queue_context;
> +
> +  node = _Scheduler_CBS_Thread_get_node( the_thread );
>
>    /* Put violating task to background until the end of period. */
> -  new_priority = the_thread->Start.initial_priority;
> -  _Thread_Set_priority( the_thread, new_priority, &unused, true );
> +  _Thread_queue_Context_clear_priority_updates( &queue_context );
> +  _Scheduler_CBS_Cancel_job(
> +    NULL,
> +    the_thread,
> +    node->deadline_node,
> +    &queue_context
> +  );
> +  _Thread_Priority_update( &queue_context );
>
>    /* Invoke callback function if any. */
> -  node = _Scheduler_CBS_Thread_get_node( the_thread );
>    if ( node->cbs_server->cbs_budget_overrun ) {
>      _Scheduler_CBS_Get_server_id(
>          node->cbs_server->task_id,
> diff --git a/cpukit/score/src/schedulercbsnodeinit.c b/cpukit/score/src/schedulercbsnodeinit.c
> index 5380069..89b6f8e 100644
> --- a/cpukit/score/src/schedulercbsnodeinit.c
> +++ b/cpukit/score/src/schedulercbsnodeinit.c
> @@ -33,4 +33,5 @@ void _Scheduler_CBS_Node_initialize(
>
>    the_node = _Scheduler_CBS_Node_downcast( node );
>    the_node->cbs_server = NULL;
> +  the_node->deadline_node = NULL;
>  }
> diff --git a/cpukit/score/src/schedulercbsreleasejob.c b/cpukit/score/src/schedulercbsreleasejob.c
> index d2169af..186f95c 100644
> --- a/cpukit/score/src/schedulercbsreleasejob.c
> +++ b/cpukit/score/src/schedulercbsreleasejob.c
> @@ -21,10 +21,12 @@
>
>  #include <rtems/score/schedulercbsimpl.h>
>
> -Thread_Control *_Scheduler_CBS_Release_job(
> +void _Scheduler_CBS_Release_job(
>    const Scheduler_Control *scheduler,
>    Thread_Control          *the_thread,
> -  uint64_t                 deadline
> +  Priority_Node           *priority_node,
> +  uint64_t                 deadline,
> +  Thread_queue_Context    *queue_context
>  )
>  {
>    Scheduler_CBS_Node   *node;
> @@ -38,5 +40,37 @@ Thread_Control *_Scheduler_CBS_Release_job(
>      the_thread->cpu_time_budget = serv_info->parameters.budget;
>    }
>
> -  return _Scheduler_EDF_Release_job( scheduler, the_thread, deadline );
> +  node->deadline_node = priority_node;
> +
> +  _Scheduler_EDF_Release_job(
> +    scheduler,
> +    the_thread,
> +    priority_node,
> +    deadline,
> +    queue_context
> +  );
> +}
> +
> +void _Scheduler_CBS_Cancel_job(
> +  const Scheduler_Control *scheduler,
> +  Thread_Control          *the_thread,
> +  Priority_Node           *priority_node,
> +  Thread_queue_Context    *queue_context
> +)
> +{
> +  Scheduler_CBS_Node *node;
> +
> +  node = _Scheduler_CBS_Thread_get_node( the_thread );
> +
> +  if ( node->deadline_node != NULL ) {
> +    _Assert( node->deadline_node == priority_node );
> +    node->deadline_node = NULL;
> +
> +    _Scheduler_EDF_Cancel_job(
> +      scheduler,
> +      the_thread,
> +      priority_node,
> +      queue_context
> +    );
> +  }
>  }
> diff --git a/cpukit/score/src/schedulercbsunblock.c b/cpukit/score/src/schedulercbsunblock.c
> index 0c1e48e..c09f471 100644
> --- a/cpukit/score/src/schedulercbsunblock.c
> +++ b/cpukit/score/src/schedulercbsunblock.c
> @@ -30,13 +30,11 @@ Scheduler_Void_or_thread _Scheduler_CBS_Unblock(
>    Thread_Control          *the_thread
>  )
>  {
> -  Scheduler_EDF_Context *context;
> -  Scheduler_CBS_Node    *node;
> -  Scheduler_CBS_Server  *serv_info;
> -  Priority_Control       priority;
> -  bool                   prepend_it;
> +  Scheduler_CBS_Node   *node;
> +  Scheduler_CBS_Server *serv_info;
> +  Priority_Control      priority;
> +  bool                  prepend_it;
>
> -  context = _Scheduler_EDF_Get_context( scheduler );
>    node = _Scheduler_CBS_Thread_get_node( the_thread );
>    serv_info = node->cbs_server;
>    priority = _Scheduler_Node_get_priority( &node->Base.Base, &prepend_it );
> @@ -55,40 +53,19 @@ Scheduler_Void_or_thread _Scheduler_CBS_Unblock(
>      Priority_Control budget_left = priority - _Watchdog_Ticks_since_boot;
>
>      if ( deadline * budget_left > budget * deadline_left ) {
> -      /* Put late unblocked task to background until the end of period. */
> -
> -      priority = node->Base.background_priority;
> -      the_thread->real_priority = priority;
> +      Thread_queue_Context queue_context;
>
> -      if (
> -        _Thread_Priority_less_than(
> -          _Thread_Get_priority( the_thread ),
> -          priority
> -        ) || !_Thread_Owns_resources( the_thread )
> -      ) {
> -        the_thread->current_priority = priority;
> -      }
> +      /* Put late unblocked task to background until the end of period. */
> +      _Thread_queue_Context_clear_priority_updates( &queue_context );
> +      _Scheduler_CBS_Cancel_job(
> +        scheduler,
> +        the_thread,
> +        node->deadline_node,
> +        &queue_context
> +      );
>      }
>    }
>
> -  node->Base.current_priority = priority;
> -  _Scheduler_EDF_Enqueue( context, &node->Base, priority );
> -
> -  /*
> -   *  If the thread that was unblocked is more important than the heir,
> -   *  then we have a new heir.  This may or may not result in a
> -   *  context switch.
> -   *
> -   *  Normal case:
> -   *    If the current thread is preemptible, then we need to do
> -   *    a context switch.
> -   *  Pseudo-ISR case:
> -   *    Even if the thread isn't preemptible, if the new heir is
> -   *    a pseudo-ISR system task, we need to do a context switch.
> -   */
> -  if ( priority < _Thread_Get_priority( _Thread_Heir ) ) {
> -    _Scheduler_Update_heir( the_thread, priority == PRIORITY_PSEUDO_ISR );
> -  }
> -
> +  _Scheduler_EDF_Unblock( scheduler, the_thread );
>    SCHEDULER_RETURN_VOID_OR_NULL;
>  }
> diff --git a/cpukit/score/src/schedulerdefaultnodeinit.c b/cpukit/score/src/schedulerdefaultnodeinit.c
> index 10e71f8..53aed52 100644
> --- a/cpukit/score/src/schedulerdefaultnodeinit.c
> +++ b/cpukit/score/src/schedulerdefaultnodeinit.c
> @@ -28,7 +28,5 @@ void _Scheduler_default_Node_initialize(
>    Priority_Control         priority
>  )
>  {
> -  (void) scheduler;
> -
> -  _Scheduler_Node_do_initialize( node, the_thread, priority );
> +  _Scheduler_Node_do_initialize( scheduler, node, the_thread, priority );
>  }
> diff --git a/cpukit/score/src/schedulerdefaultreleasejob.c b/cpukit/score/src/schedulerdefaultreleasejob.c
> index 7272fc1..490d58b 100644
> --- a/cpukit/score/src/schedulerdefaultreleasejob.c
> +++ b/cpukit/score/src/schedulerdefaultreleasejob.c
> @@ -21,26 +21,30 @@
>
>  #include <rtems/score/scheduler.h>
>
> -Thread_Control *_Scheduler_default_Release_job(
> +void _Scheduler_default_Release_job(
>    const Scheduler_Control *scheduler,
>    Thread_Control          *the_thread,
> -  uint64_t                 deadline
> +  Priority_Node           *priority_node,
> +  uint64_t                 deadline,
> +  Thread_queue_Context    *queue_context
>  )
>  {
>    (void) scheduler;
>    (void) the_thread;
> +  (void) priority_node;
>    (void) deadline;
> -
> -  return NULL;
> +  (void) queue_context;
>  }
>
> -Thread_Control *_Scheduler_default_Cancel_job(
> +void _Scheduler_default_Cancel_job(
>    const Scheduler_Control *scheduler,
> -  Thread_Control          *the_thread
> +  Thread_Control          *the_thread,
> +  Priority_Node           *priority_node,
> +  Thread_queue_Context    *queue_context
>  )
>  {
>    (void) scheduler;
>    (void) the_thread;
> -
> -  return NULL;
> +  (void) priority_node;
> +  (void) queue_context;
>  }
> diff --git a/cpukit/score/src/scheduleredfchangepriority.c b/cpukit/score/src/scheduleredfchangepriority.c
> index 9a73128..8940b1d 100644
> --- a/cpukit/score/src/scheduleredfchangepriority.c
> +++ b/cpukit/score/src/scheduleredfchangepriority.c
> @@ -54,16 +54,12 @@ Scheduler_Void_or_thread _Scheduler_EDF_Update_priority(
>    node = _Scheduler_EDF_Thread_get_node( the_thread );
>    priority = _Scheduler_Node_get_priority( &node->Base, &prepend_it );
>
> -  if ( priority == node->current_priority ) {
> +  if ( priority == node->priority ) {
>      /* Nothing to do */
>      SCHEDULER_RETURN_VOID_OR_NULL;
>    }
>
> -  if ( ( priority & SCHEDULER_EDF_PRIO_MSB ) != 0 ) {
> -    node->background_priority = priority;
> -  }
> -
> -  node->current_priority = priority;
> +  node->priority = priority;
>    context = _Scheduler_EDF_Get_context( scheduler );
>
>    _Scheduler_EDF_Extract( context, node );
> diff --git a/cpukit/score/src/scheduleredfnodeinit.c b/cpukit/score/src/scheduleredfnodeinit.c
> index d290bd7..94f8fac 100644
> --- a/cpukit/score/src/scheduleredfnodeinit.c
> +++ b/cpukit/score/src/scheduleredfnodeinit.c
> @@ -29,11 +29,9 @@ void _Scheduler_EDF_Node_initialize(
>  {
>    Scheduler_EDF_Node *the_node;
>
> -  (void) scheduler;
> -
> -  _Scheduler_Node_do_initialize( node, the_thread, priority );
> +  _Scheduler_Node_do_initialize( scheduler, node, the_thread, priority );
>
>    the_node = _Scheduler_EDF_Node_downcast( node );
> -  the_node->thread = the_thread;
>    _RBTree_Initialize_node( &the_node->Node );
> +  the_node->priority = priority;
>  }
> diff --git a/cpukit/score/src/scheduleredfreleasejob.c b/cpukit/score/src/scheduleredfreleasejob.c
> index 4c74c48..c19d9b9 100644
> --- a/cpukit/score/src/scheduleredfreleasejob.c
> +++ b/cpukit/score/src/scheduleredfreleasejob.c
> @@ -20,75 +20,47 @@
>
>  #include <rtems/score/scheduleredfimpl.h>
>
> -static bool _Scheduler_EDF_Release_job_filter(
> -  Thread_Control   *the_thread,
> -  Priority_Control *new_priority_p,
> -  void             *arg
> +void _Scheduler_EDF_Release_job(
> +  const Scheduler_Control *scheduler,
> +  Thread_Control          *the_thread,
> +  Priority_Node           *priority_node,
> +  uint64_t                 deadline,
> +  Thread_queue_Context    *queue_context
>  )
>  {
> -  Scheduler_EDF_Node *node;
> -  Priority_Control    current_priority;
> -  Priority_Control    new_priority;
> +  (void) scheduler;
>
> -  node = _Scheduler_EDF_Thread_get_node( the_thread );
> +  _Thread_Wait_acquire_critical( the_thread, queue_context );
>
> -  current_priority = _Thread_Get_priority( the_thread );
> -  new_priority = *new_priority_p;
> +  _Priority_Node_set_priority( priority_node, deadline );
>
> -  node->current_priority = new_priority;
> -  the_thread->real_priority = new_priority;
> +  if ( _Priority_Node_is_active( priority_node ) ) {
> +    _Thread_Priority_changed(
> +      the_thread,
> +      priority_node,
> +      false,
> +      queue_context
> +    );
> +  } else {
> +    _Thread_Priority_add( the_thread, priority_node, queue_context );
> +  }
>
> -  return _Thread_Priority_less_than( current_priority, new_priority )
> -    || !_Thread_Owns_resources( the_thread );
> +  _Thread_Wait_release_critical( the_thread, queue_context );
>  }
>
> -Thread_Control *_Scheduler_EDF_Release_job(
> +void _Scheduler_EDF_Cancel_job(
>    const Scheduler_Control *scheduler,
>    Thread_Control          *the_thread,
> -  uint64_t                 deadline
> -)
> -{
> -  return _Thread_Apply_priority(
> -    the_thread,
> -    deadline,
> -    NULL,
> -    _Scheduler_EDF_Release_job_filter,
> -    true
> -  );
> -}
> -
> -static bool _Scheduler_EDF_Cancel_job_filter(
> -  Thread_Control   *the_thread,
> -  Priority_Control *new_priority_p,
> -  void             *arg
> +  Priority_Node           *priority_node,
> +  Thread_queue_Context    *queue_context
>  )
>  {
> -  Scheduler_EDF_Node *node;
> -  Priority_Control    current_priority;
> -  Priority_Control    new_priority;
> +  (void) scheduler;
>
> -  node = _Scheduler_EDF_Thread_get_node( the_thread );
> +  _Thread_Wait_acquire_critical( the_thread, queue_context );
>
> -  current_priority = _Thread_Get_priority( the_thread );
> -  new_priority = node->background_priority;
> +  _Thread_Priority_remove( the_thread, priority_node, queue_context );
> +  _Priority_Node_set_inactive( priority_node );
>
> -  node->current_priority = new_priority;
> -  the_thread->real_priority = new_priority;
> -
> -  return _Thread_Priority_less_than( current_priority, new_priority )
> -    || !_Thread_Owns_resources( the_thread );
> -}
> -
> -Thread_Control *_Scheduler_EDF_Cancel_job(
> -  const Scheduler_Control *scheduler,
> -  Thread_Control          *the_thread
> -)
> -{
> -  return _Thread_Apply_priority(
> -    the_thread,
> -    0,
> -    NULL,
> -    _Scheduler_EDF_Cancel_job_filter,
> -    true
> -  );
> +  _Thread_Wait_release_critical( the_thread, queue_context );
>  }
> diff --git a/cpukit/score/src/scheduleredfunblock.c b/cpukit/score/src/scheduleredfunblock.c
> index 9b156ec..a5cc4b6 100644
> --- a/cpukit/score/src/scheduleredfunblock.c
> +++ b/cpukit/score/src/scheduleredfunblock.c
> @@ -37,7 +37,7 @@ Scheduler_Void_or_thread _Scheduler_EDF_Unblock(
>    priority = _Scheduler_Node_get_priority( &node->Base, &prepend_it );
>    (void) prepend_it;
>
> -  node->current_priority = priority;
> +  node->priority = priority;
>    _Scheduler_EDF_Enqueue( context, node, priority );
>
>    /*
> diff --git a/cpukit/score/src/scheduleredfyield.c b/cpukit/score/src/scheduleredfyield.c
> index 06c1b46..3e64e5c 100644
> --- a/cpukit/score/src/scheduleredfyield.c
> +++ b/cpukit/score/src/scheduleredfyield.c
> @@ -33,7 +33,7 @@ Scheduler_Void_or_thread _Scheduler_EDF_Yield(
>    node = _Scheduler_EDF_Thread_get_node( the_thread );
>
>    _Scheduler_EDF_Extract( context, node );
> -  _Scheduler_EDF_Enqueue( context, node, node->current_priority );
> +  _Scheduler_EDF_Enqueue( context, node, node->priority );
>    _Scheduler_EDF_Schedule_body( scheduler, the_thread, true );
>
>    SCHEDULER_RETURN_VOID_OR_NULL;
> diff --git a/cpukit/score/src/schedulerpriority.c b/cpukit/score/src/schedulerpriority.c
> index 11cee92..ddfd973 100644
> --- a/cpukit/score/src/schedulerpriority.c
> +++ b/cpukit/score/src/schedulerpriority.c
> @@ -43,7 +43,7 @@ void _Scheduler_priority_Node_initialize(
>    Scheduler_priority_Context *context;
>    Scheduler_priority_Node    *the_node;
>
> -  _Scheduler_Node_do_initialize( node, the_thread, priority );
> +  _Scheduler_Node_do_initialize( scheduler, node, the_thread, priority );
>
>    context = _Scheduler_priority_Get_context( scheduler );
>    the_node = _Scheduler_priority_Node_downcast( node );
> diff --git a/cpukit/score/src/schedulerprioritysmp.c b/cpukit/score/src/schedulerprioritysmp.c
> index 07e7af4..e624a6a 100644
> --- a/cpukit/score/src/schedulerprioritysmp.c
> +++ b/cpukit/score/src/schedulerprioritysmp.c
> @@ -57,7 +57,12 @@ void _Scheduler_priority_SMP_Node_initialize(
>    Scheduler_priority_SMP_Node    *the_node;
>
>    the_node = _Scheduler_priority_SMP_Node_downcast( node );
> -  _Scheduler_SMP_Node_initialize( &the_node->Base, the_thread, priority );
> +  _Scheduler_SMP_Node_initialize(
> +    scheduler,
> +    &the_node->Base,
> +    the_thread,
> +    priority
> +  );
>
>    context = _Scheduler_Get_context( scheduler );
>    self = _Scheduler_priority_SMP_Get_self( context );
> diff --git a/cpukit/score/src/schedulersimplesmp.c b/cpukit/score/src/schedulersimplesmp.c
> index 8f86ea8..9606896 100644
> --- a/cpukit/score/src/schedulersimplesmp.c
> +++ b/cpukit/score/src/schedulersimplesmp.c
> @@ -52,7 +52,7 @@ void _Scheduler_simple_SMP_Node_initialize(
>    Scheduler_SMP_Node *the_node;
>
>    the_node = _Scheduler_SMP_Node_downcast( node );
> -  _Scheduler_SMP_Node_initialize( the_node, the_thread, priority );
> +  _Scheduler_SMP_Node_initialize( scheduler, the_node, the_thread, priority );
>  }
>
>  static void _Scheduler_simple_SMP_Do_update(
> diff --git a/cpukit/score/src/schedulerstrongapa.c b/cpukit/score/src/schedulerstrongapa.c
> index 5d7c7f7..fc6d012 100644
> --- a/cpukit/score/src/schedulerstrongapa.c
> +++ b/cpukit/score/src/schedulerstrongapa.c
> @@ -183,7 +183,12 @@ void _Scheduler_strong_APA_Node_initialize(
>    Scheduler_strong_APA_Node    *the_node;
>
>    the_node = _Scheduler_strong_APA_Node_downcast( node );
> -  _Scheduler_SMP_Node_initialize( &the_node->Base, the_thread, priority );
> +  _Scheduler_SMP_Node_initialize(
> +    scheduler,
> +    &the_node->Base,
> +    the_thread,
> +    priority
> +  );
>
>    context = _Scheduler_Get_context( scheduler );
>    self = _Scheduler_strong_APA_Get_self( context );
> diff --git a/cpukit/score/src/thread.c b/cpukit/score/src/thread.c
> index c569ae5..864b21b 100644
> --- a/cpukit/score/src/thread.c
> +++ b/cpukit/score/src/thread.c
> @@ -32,9 +32,7 @@
>  THREAD_OFFSET_ASSERT( Object );
>  THREAD_OFFSET_ASSERT( Join_queue );
>  THREAD_OFFSET_ASSERT( current_state );
> -THREAD_OFFSET_ASSERT( current_priority );
> -THREAD_OFFSET_ASSERT( real_priority );
> -THREAD_OFFSET_ASSERT( priority_restore_hint );
> +THREAD_OFFSET_ASSERT( Real_priority );
>  THREAD_OFFSET_ASSERT( resource_count );
>  THREAD_OFFSET_ASSERT( Scheduler );
>  THREAD_OFFSET_ASSERT( Wait );
> diff --git a/cpukit/score/src/threadchangepriority.c b/cpukit/score/src/threadchangepriority.c
> index 3429e1a..42172b2 100644
> --- a/cpukit/score/src/threadchangepriority.c
> +++ b/cpukit/score/src/threadchangepriority.c
> @@ -10,6 +10,8 @@
>   *  COPYRIGHT (c) 1989-2014.
>   *  On-Line Applications Research Corporation (OAR).
>   *
> + *  Copyright (c) 2013, 2016 embedded brains GmbH
> + *
>   *  The license and distribution terms for this file may be
>   *  found in the file LICENSE in this distribution or at
>   *  http://www.rtems.org/license/LICENSE.
> @@ -20,145 +22,313 @@
>  #endif
>
>  #include <rtems/score/threadimpl.h>
> +#include <rtems/score/assert.h>
>  #include <rtems/score/schedulerimpl.h>
>
> -static Thread_Control *_Thread_Apply_priority_locked(
> +static void _Thread_Set_scheduler_node_priority(
> +  Priority_Aggregation *priority_aggregation,
> +  bool                  prepend_it
> +)
> +{
> +  _Scheduler_Node_set_priority(
> +    SCHEDULER_NODE_OF_WAIT_PRIORITY_NODE( priority_aggregation ),
> +    _Priority_Get_priority( priority_aggregation ),
> +    prepend_it
> +  );
> +}
> +
> +#if defined(RTEMS_SMP)
> +static void _Thread_Priority_action_add(
> +  Priority_Aggregation *priority_aggregation,
> +  Priority_Actions     *priority_actions,
> +  void                 *arg
> +)
> +{
> +  _Thread_Set_scheduler_node_priority( priority_aggregation, false );
> +  _Priority_Set_action_type( priority_aggregation, PRIORITY_ACTION_ADD );
> +  _Priority_Actions_add( priority_actions, priority_aggregation );
> +}
> +
> +static void _Thread_Priority_action_remove(
> +  Priority_Aggregation *priority_aggregation,
> +  Priority_Actions     *priority_actions,
> +  void                 *arg
> +)
> +{
> +  _Thread_Set_scheduler_node_priority( priority_aggregation, true );
> +  _Priority_Set_action_type( priority_aggregation, PRIORITY_ACTION_REMOVE );
> +  _Priority_Actions_add( priority_actions, priority_aggregation );
> +}
> +#endif
> +
> +static void _Thread_Priority_action_change(
> +  Priority_Aggregation *priority_aggregation,
> +  bool                  prepend_it,
> +  Priority_Actions     *priority_actions,
> +  void                 *arg
> +)
> +{
> +  _Thread_Set_scheduler_node_priority( priority_aggregation, prepend_it );
> +#if defined(RTEMS_SMP)
> +  _Priority_Set_action_type( priority_aggregation, PRIORITY_ACTION_CHANGE );
> +#elif defined(RTEMS_DEBUG)
> +  _Priority_Set_action_type( priority_aggregation, PRIORITY_ACTION_INVALID );
> +#endif
> +  _Priority_Actions_add( priority_actions, priority_aggregation );
> +}
> +
> +static void _Thread_Priority_do_perform_actions(
>    Thread_Control                *the_thread,
> -  Priority_Control               new_priority,
> -  void                          *arg,
> -  Thread_Change_priority_filter  filter,
> +  Thread_queue_Queue            *queue,
> +  const Thread_queue_Operations *operations,
>    bool                           prepend_it,
>    Thread_queue_Context          *queue_context
>  )
>  {
> -  /*
> -   * For simplicity set the priority restore hint unconditionally since this is
> -   * an average case optimization.  Otherwise complicated atomic operations
> -   * would be necessary.  Synchronize with a potential read of the resource
> -   * count in the filter function.  See also _CORE_mutex_Surrender(),
> -   * _Thread_Set_priority_filter() and _Thread_Restore_priority_filter().
> -   */
> -  the_thread->priority_restore_hint = true;
> -  _Atomic_Fence( ATOMIC_ORDER_ACQ_REL );
> -
> -  /*
> -   *  Do not bother recomputing all the priority related information if
> -   *  we are not REALLY changing priority.
> -   */
> -  if ( ( *filter )( the_thread, &new_priority, arg ) ) {
> -    _Scheduler_Thread_set_priority( the_thread, new_priority, prepend_it );
> -
> -    ( *the_thread->Wait.operations->priority_change )(
> -      the_thread->Wait.queue,
> -      the_thread,
> -      new_priority
> +  Priority_Actions      actions_now;
> +  Priority_Aggregation *priority_aggregation;
> +
> +  _Assert( !_Priority_Actions_is_empty( &queue_context->Priority.Actions ) );
> +
> +  _Priority_Actions_move( &actions_now, &queue_context->Priority.Actions );
> +  priority_aggregation = _Priority_Actions_get_first( &actions_now );
> +
> +  do {
> +    Priority_Aggregation *priority_aggregation_next;
> +    Priority_Node        *priority_action_node;
> +    Priority_Action_type  priority_action_type;
> +
> +    priority_aggregation_next = _Priority_Get_next_action(
> +      priority_aggregation
> +    );
> +
> +    priority_action_node = priority_aggregation->Action.node;
> +    priority_action_type = priority_aggregation->Action.type;
> +
> +    switch ( priority_action_type ) {
> +      case PRIORITY_ACTION_ADD:
> +#if defined(RTEMS_SMP)
> +        _Priority_Insert(
> +          priority_aggregation,
> +          priority_action_node,
> +          &queue_context->Priority.Actions,
> +          _Thread_Priority_action_add,
> +          _Thread_Priority_action_change,
> +          NULL
> +        );
> +#else
> +        _Priority_Non_empty_insert(
> +          priority_aggregation,
> +          priority_action_node,
> +          &queue_context->Priority.Actions,
> +          _Thread_Priority_action_change,
> +          NULL
> +        );
> +#endif
> +        break;
> +      case PRIORITY_ACTION_REMOVE:
> +#if defined(RTEMS_SMP)
> +        _Priority_Extract(
> +          priority_aggregation,
> +          priority_action_node,
> +          &queue_context->Priority.Actions,
> +          _Thread_Priority_action_remove,
> +          _Thread_Priority_action_change,
> +          NULL
> +        );
> +#else
> +        _Priority_Extract_non_empty(
> +          priority_aggregation,
> +          priority_action_node,
> +          &queue_context->Priority.Actions,
> +          _Thread_Priority_action_change,
> +          NULL
> +        );
> +#endif
> +        break;
> +      default:
> +        _Assert( priority_action_type == PRIORITY_ACTION_CHANGE );
> +        _Priority_Change(
> +          priority_aggregation,
> +          priority_action_node,
> +          prepend_it,
> +          &queue_context->Priority.Actions,
> +          _Thread_Priority_action_change,
> +          NULL
> +        );
> +        break;
> +    }
> +
> +    priority_aggregation = priority_aggregation_next;
> +  } while ( _Priority_Actions_is_valid( priority_aggregation ) );
> +
> +  if ( !_Priority_Actions_is_empty( &queue_context->Priority.Actions ) ) {
> +    _Thread_queue_Context_add_priority_update( queue_context, the_thread );
> +    ( *operations->priority_actions )(
> +      queue,
> +      &queue_context->Priority.Actions
>      );
> -  } else {
> -    the_thread = NULL;
>    }
> +}
>
> -  return the_thread;
> +void _Thread_Priority_perform_actions(
> +  Thread_Control       *start_of_path,
> +  Thread_queue_Context *queue_context
> +)
> +{
> +#if defined(RTEMS_SMP)
> +  Thread_queue_Link *link;
> +#endif
> +  Thread_Control    *the_thread;
> +  size_t             update_count;
> +
> +  _Assert( start_of_path != NULL );
> +
> +#if defined(RTEMS_SMP)
> +  link = &queue_context->Path.Start;
> +#endif
> +  the_thread = start_of_path;
> +  update_count = _Thread_queue_Context_get_priority_updates( queue_context );
> +
> +  while ( true ) {
> +    Thread_queue_Queue *queue;
> +
> +#if defined(RTEMS_SMP)
> +    _Assert( link->owner == the_thread );
> +    queue = link->Lock_context.Wait.queue;
> +#else
> +    queue = the_thread->Wait.queue;
> +#endif
> +
> +    _Thread_Priority_do_perform_actions(
> +      the_thread,
> +      queue,
> +      the_thread->Wait.operations,
> +      false,
> +      queue_context
> +    );
> +
> +    if ( _Priority_Actions_is_empty( &queue_context->Priority.Actions ) ) {
> +      return;
> +    }
> +
> +    _Assert( queue != NULL );
> +    the_thread = queue->owner;
> +    _Assert( the_thread != NULL );
> +
> +#if defined(RTEMS_SMP)
> +    link = THREAD_QUEUE_LINK_OF_PATH_NODE( _Chain_Next( &link->Path_node ) );
> +#endif
> +    _Thread_queue_Context_set_priority_updates( queue_context, update_count );

Has the queue_context->update_count changed since it was earlier read?
If yes, why is it correct to restore it?

> +  }
>  }
>
> -Thread_Control *_Thread_Apply_priority(
> -  Thread_Control                *the_thread,
> -  Priority_Control               new_priority,
> -  void                          *arg,
> -  Thread_Change_priority_filter  filter,
> -  bool                           prepend_it
> +static void _Thread_Priority_apply(
> +  Thread_Control       *the_thread,
> +  Priority_Node        *priority_action_node,
> +  Thread_queue_Context *queue_context,
> +  bool                  prepend_it,
> +  Priority_Action_type  priority_action_type
>  )
>  {
> -  Thread_queue_Context  queue_context;
> -  Thread_Control       *the_thread_to_update;
> +  Scheduler_Node     *own_node;
> +  Thread_queue_Queue *queue;
>
> -  _Thread_Wait_acquire( the_thread, &queue_context );
> -  the_thread_to_update = _Thread_Apply_priority_locked(
> +  own_node = _Thread_Scheduler_get_own_node( the_thread );
> +  _Priority_Actions_initialize_one(
> +    &queue_context->Priority.Actions,
> +    &own_node->Wait.Priority,
> +    priority_action_node,
> +    priority_action_type
> +  );
> +  queue = the_thread->Wait.queue;
> +  _Thread_Priority_do_perform_actions(
>      the_thread,
> -    new_priority,
> -    arg,
> -    filter,
> +    queue,
> +    the_thread->Wait.operations,
>      prepend_it,
> -    &queue_context
> +    queue_context
>    );
> -  _Thread_Wait_release( the_thread, &queue_context );
> -  return the_thread_to_update;
> -}
> -
> -void _Thread_Update_priority( Thread_Control *the_thread )
> -{
> -  if ( the_thread != NULL ) {
> -    ISR_lock_Context lock_context;
>
> -    _Thread_State_acquire( the_thread, &lock_context );
> -    _Scheduler_Update_priority( the_thread );
> -    _Thread_State_release( the_thread, &lock_context );
> +  if ( !_Priority_Actions_is_empty( &queue_context->Priority.Actions ) ) {
> +    _Thread_queue_Path_acquire_critical( queue, the_thread, queue_context );
> +    _Thread_Priority_perform_actions( queue->owner, queue_context );
> +    _Thread_queue_Path_release_critical( queue_context );
>    }
>  }
>
> -void _Thread_Change_priority(
> -  Thread_Control                *the_thread,
> -  Priority_Control               new_priority,
> -  void                          *arg,
> -  Thread_Change_priority_filter  filter,
> -  bool                           prepend_it
> +void _Thread_Priority_add(
> +  Thread_Control       *the_thread,
> +  Priority_Node        *priority_node,
> +  Thread_queue_Context *queue_context
>  )
>  {
> -  the_thread = _Thread_Apply_priority(
> +  _Thread_Priority_apply(
>      the_thread,
> -    new_priority,
> -    arg,
> -    filter,
> -    prepend_it
> +    priority_node,
> +    queue_context,
> +    false,
> +    PRIORITY_ACTION_ADD
>    );
> -  _Thread_Update_priority( the_thread );
>  }
>
> -static bool _Thread_Raise_priority_filter(
> -  Thread_Control   *the_thread,
> -  Priority_Control *new_priority,
> -  void             *arg
> +void _Thread_Priority_remove(
> +  Thread_Control       *the_thread,
> +  Priority_Node        *priority_node,
> +  Thread_queue_Context *queue_context
>  )
>  {
> -  return _Thread_Priority_less_than(
> -    _Thread_Get_priority( the_thread ),
> -    *new_priority
> +  _Thread_Priority_apply(
> +    the_thread,
> +    priority_node,
> +    queue_context,
> +    true,
> +    PRIORITY_ACTION_REMOVE
>    );
>  }
>
> -void _Thread_Raise_priority(
> -  Thread_Control   *the_thread,
> -  Priority_Control  new_priority
> +void _Thread_Priority_changed(
> +  Thread_Control       *the_thread,
> +  Priority_Node        *priority_node,
> +  bool                  prepend_it,
> +  Thread_queue_Context *queue_context
>  )
>  {
> -  _Thread_Change_priority(
> +  _Thread_Priority_apply(
>      the_thread,
> -    new_priority,
> -    NULL,
> -    _Thread_Raise_priority_filter,
> -    false
> +    priority_node,
> +    queue_context,
> +    prepend_it,
> +    PRIORITY_ACTION_CHANGE
>    );
>  }
>
> -static bool _Thread_Restore_priority_filter(
> -  Thread_Control   *the_thread,
> -  Priority_Control *new_priority,
> -  void             *arg
> +void _Thread_Priority_replace(
> +  Thread_Control *the_thread,
> +  Priority_Node  *victim_node,
> +  Priority_Node  *replacement_node
>  )
>  {
> -  *new_priority = the_thread->real_priority;
> -
> -  the_thread->priority_restore_hint = false;
> +  Scheduler_Node *own_node;
>
> -  return *new_priority != _Thread_Get_priority( the_thread );
> +  own_node = _Thread_Scheduler_get_own_node( the_thread );
> +  _Priority_Replace( &own_node->Wait.Priority, victim_node, replacement_node );
>  }
>
> -void _Thread_Restore_priority( Thread_Control *the_thread )
> +void _Thread_Priority_update( Thread_queue_Context *queue_context )
>  {
> -  _Thread_Change_priority(
> -    the_thread,
> -    0,
> -    NULL,
> -    _Thread_Restore_priority_filter,
> -    true
> -  );
> +  size_t i;
> +  size_t n;
> +
> +  n = queue_context->Priority.update_count;
> +
> +  for ( i = 0; i < n ; ++i ) {
> +    Thread_Control   *the_thread;
> +    ISR_lock_Context  lock_context;
> +
> +    the_thread = queue_context->Priority.update[ i ];
> +    _Thread_State_acquire( the_thread, &lock_context );
> +    _Scheduler_Update_priority( the_thread );
> +    _Thread_State_release( the_thread, &lock_context );
> +  }

Why doesn't this decrement the update_count after completing the
update? I'm missing some important detail about the "lifetime" of
these update counters.

[...]

The rest looked relatively straightforward on a quick skim.

-Gedare



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