score: Rework CORE inherit priority mutex

Provide dedicated seize and surrender methods for inherit priority
mutexes.  This eliminates CORE_mutex_Attributes.

12 files changed, 159 insertions, 385 deletions

diff --git a/cpukit/score/Makefile.am b/cpukit/score/Makefile.am
index fae6fc37bb..29e822d47d 100644
--- a/cpukit/score/Makefile.am
+++ b/cpukit/score/Makefile.am
@@ -181,8 +181,8 @@ libscore_a_SOURCES += src/coremsg.c src/coremsgbroadcast.c \
     src/coremsgsubmit.c
 
 ## CORE_MUTEX_C_FILES
-libscore_a_SOURCES += src/coremutex.c \
-    src/coremutexseize.c src/coremutexsurrender.c
+libscore_a_SOURCES += src/coremutexseize.c
+libscore_a_SOURCES += src/coremutexsurrender.c
 
 ## CORE_PERCPU_C_FILES
 libscore_a_SOURCES += src/percpu.c
diff --git a/cpukit/score/include/rtems/score/apimutex.h b/cpukit/score/include/rtems/score/apimutex.h
index 1a4b1ee445..aa08481c83 100644
--- a/cpukit/score/include/rtems/score/apimutex.h
+++ b/cpukit/score/include/rtems/score/apimutex.h
@@ -46,7 +46,7 @@ typedef struct {
   /**
    * Contains the SuperCore mutex information.
    */
-  CORE_mutex_Control Mutex;
+  CORE_recursive_mutex_Control Mutex;
 
   /**
    * @brief The thread life protection state before the outer-most mutex
diff --git a/cpukit/score/include/rtems/score/coremutex.h b/cpukit/score/include/rtems/score/coremutex.h
index 704ea0da24..2bde8b5ebd 100644
--- a/cpukit/score/include/rtems/score/coremutex.h
+++ b/cpukit/score/include/rtems/score/coremutex.h
@@ -42,47 +42,6 @@ extern "C" {
 /**@{*/
 
 /**
- *  @brief The possible behaviors for lock nesting.
- *
- *  This enumerated type defines the possible behaviors for
- *  lock nesting.
- */
-typedef enum {
-  /**
-   *    This sequence has no blocking or errors:
-   *
-   *         + lock(m)
-   *         + lock(m)
-   *         + unlock(m)
-   *         + unlock(m)
-   */
-  CORE_MUTEX_NESTING_ACQUIRES,
-#if defined(RTEMS_POSIX_API)
-  /**
-   *    This sequence returns an error at the indicated point:
-   *
-   *        + lock(m)
-   *        + lock(m)   - already locked error
-   *        + unlock(m)
-   */
-  CORE_MUTEX_NESTING_IS_ERROR,
-#endif
-}  CORE_mutex_Nesting_behaviors;
-
-/**
- *  @brief The control block used to manage attributes of each mutex.
- *
- *  The following defines the control block used to manage the
- *  attributes of each mutex.
- */
-typedef struct {
-  /** This field determines what the behavior of this mutex instance will
-   *  be when attempting to acquire the mutex when it is already locked.
-   */
-  CORE_mutex_Nesting_behaviors lock_nesting_behavior;
-}   CORE_mutex_Attributes;
-
-/**
  *  @brief Control block used to manage each mutex.
  *
  *  The following defines the control block used to manage each mutex.
@@ -93,14 +52,6 @@ typedef struct {
    */
   Thread_queue_Control    Wait_queue;
 
-  /** This element is the set of attributes which define this instance's
-   *  behavior.
-   */
-  CORE_mutex_Attributes   Attributes;
-  /** This element contains the number of times the mutex has been acquired
-   *  nested.  This must be zero (0) before the mutex is actually unlocked.
-   */
-  uint32_t                nest_count;
   /** This element points to the thread which is currently holding this mutex.
    *  The holder is the last thread to successfully lock the mutex and which
    *  has not unlocked it.  If the thread is not locked, there is no holder.
diff --git a/cpukit/score/include/rtems/score/coremuteximpl.h b/cpukit/score/include/rtems/score/coremuteximpl.h
index f459743346..69311e4101 100644
--- a/cpukit/score/include/rtems/score/coremuteximpl.h
+++ b/cpukit/score/include/rtems/score/coremuteximpl.h
@@ -35,26 +35,13 @@ extern "C" {
 
 #define CORE_MUTEX_TQ_OPERATIONS &_Thread_queue_Operations_priority
 
-/**
- *  @brief Initializes the mutex based on the parameters passed.
- *
- *  This routine initializes the mutex based on the parameters passed.
- *
- *  @param[in,out] the_mutex is the mutex to initalize
- *  @param[in,out] executing The currently executing thread.
- *  @param[in] the_mutex_attributes is the attributes associated with this
- *         mutex instance
- *  @param[in] initially_locked If true, then the mutex is initially locked by
- *  the executing thread.
- *
- *  @retval This method returns STATUS_SUCCESSFUL if successful.
- */
-Status_Control _CORE_mutex_Initialize(
-  CORE_mutex_Control           *the_mutex,
-  Thread_Control               *executing,
-  const CORE_mutex_Attributes  *the_mutex_attributes,
-  bool                          initially_locked
-);
+RTEMS_INLINE_ROUTINE void _CORE_mutex_Initialize(
+  CORE_mutex_Control *the_mutex
+)
+{
+  _Thread_queue_Initialize( &the_mutex->Wait_queue );
+  the_mutex->holder = NULL;
+}
 
 RTEMS_INLINE_ROUTINE void _CORE_mutex_Destroy( CORE_mutex_Control *the_mutex )
 {
@@ -83,25 +70,6 @@ RTEMS_INLINE_ROUTINE void _CORE_mutex_Release(
   );
 }
 
-/**
- *  @brief Performs the blocking portion of a mutex obtain.
- *
- *  This routine performs the blocking portion of a mutex obtain.
- *  It is an actual subroutine and is not implemented as something
- *  that may be inlined.
- *
- *  @param[in,out] the_mutex is the mutex to attempt to lock
- *  @param[in,out] executing The currently executing thread.
- *  @param[in] timeout is the maximum number of ticks to block
- *  @param[in] lock_context is the interrupt level
- */
-Status_Control _CORE_mutex_Seize_interrupt_blocking(
-  CORE_mutex_Control   *the_mutex,
-  Thread_Control       *executing,
-  Watchdog_Interval     timeout,
-  Thread_queue_Context *queue_context
-);
-
 RTEMS_INLINE_ROUTINE Thread_Control *_CORE_mutex_Get_owner(
   const CORE_mutex_Control *the_mutex
 )
@@ -127,124 +95,14 @@ RTEMS_INLINE_ROUTINE bool _CORE_mutex_Is_locked(
   return _CORE_mutex_Get_owner( the_mutex ) != NULL;
 }
 
-/**
- *  @brief Attempt to receive a unit from the_mutex.
- *
- *  This routine attempts to receive a unit from the_mutex.
- *  If a unit is available or if the wait flag is false, then the routine
- *  returns.  Otherwise, the calling task is blocked until a unit becomes
- *  available.
- *
- *  @param[in,out] executing The currently executing thread.
- *  @param[in,out] the_mutex is the mutex to attempt to lock
- *  @param[in] queue_context is the interrupt level
- *
- *  @retval STATUS_UNAVAILABLE The mutex is already locked.
- *  @retval other Otherwise.
- */
-RTEMS_INLINE_ROUTINE Status_Control _CORE_mutex_Seize_interrupt_trylock(
-  CORE_mutex_Control   *the_mutex,
-  Thread_Control       *executing,
-  Thread_queue_Context *queue_context
-)
-{
-  /* disabled when you get here */
-
-  if ( !_CORE_mutex_Is_locked( the_mutex ) ) {
-    the_mutex->holder     = executing;
-    the_mutex->nest_count = 1;
-    ++executing->resource_count;
-
-    _CORE_mutex_Release( the_mutex, queue_context );
-    return STATUS_SUCCESSFUL;
-  }
-
-  /*
-   *  At this point, we know the mutex was not available.  If this thread
-   *  is the thread that has locked the mutex, let's see if we are allowed
-   *  to nest access.
-   */
-  if ( _Thread_Is_executing( the_mutex->holder ) ) {
-    switch ( the_mutex->Attributes.lock_nesting_behavior ) {
-      case CORE_MUTEX_NESTING_ACQUIRES:
-        the_mutex->nest_count++;
-        _CORE_mutex_Release( the_mutex, queue_context );
-        return STATUS_SUCCESSFUL;
-      #if defined(RTEMS_POSIX_API)
-        case CORE_MUTEX_NESTING_IS_ERROR:
-          _CORE_mutex_Release( the_mutex, queue_context );
-          return STATUS_NESTING_NOT_ALLOWED;
-      #endif
-    }
-  }
-
-  /*
-   *  The mutex is not available and the caller must deal with the possibility
-   *  of blocking.
-   */
-  return STATUS_UNAVAILABLE;
-}
-
-/**
- *  @brief Attempt to obtain the mutex.
- *
- *  This routine attempts to obtain the mutex.  If the mutex is available,
- *  then it will return immediately.  Otherwise, it will invoke the
- *  support routine @a _Core_mutex_Seize_interrupt_blocking.
- *
- *  @param[in] the_mutex is the mutex to attempt to lock
- *  @param[in] wait is true if the thread is willing to wait
- *  @param[in] timeout is the maximum number of ticks to block
- *  @param[in] queue_context is a temporary variable used to contain the ISR
- *         disable level cookie
- *
- *  @note If the mutex is called from an interrupt service routine,
- *        with context switching disabled, or before multitasking,
- *        then a fatal error is generated.
- *
- *  The logic on this routine is as follows:
- *
- *  * If incorrect system state
- *      return an error
- *  * If mutex is available without any contention or blocking
- *      obtain it with interrupts disabled and returned
- *  * If the caller is willing to wait
- *      then they are blocked.
- */
-RTEMS_INLINE_ROUTINE Status_Control _CORE_mutex_Seize(
+Status_Control _CORE_mutex_Seize_slow(
   CORE_mutex_Control   *the_mutex,
   Thread_Control       *executing,
+  Thread_Control       *owner,
   bool                  wait,
   Watchdog_Interval     timeout,
   Thread_queue_Context *queue_context
-)
-{
-  Status_Control status;
-
-  _CORE_mutex_Acquire_critical( the_mutex, queue_context );
-
-  status = _CORE_mutex_Seize_interrupt_trylock(
-    the_mutex,
-    executing,
-    queue_context
-  );
-
-  if ( status != STATUS_UNAVAILABLE ) {
-    return status;
-  }
-
-  if ( !wait ) {
-    _CORE_mutex_Release( the_mutex, queue_context );
-    return status;
-  }
-
-  return _CORE_mutex_Seize_interrupt_blocking(
-    the_mutex,
-    executing,
-    timeout,
-    queue_context
-  );
-}
+);
 
 Status_Control _CORE_mutex_Seize_no_protocol_slow(
   CORE_mutex_Control            *the_mutex,
@@ -255,8 +113,11 @@ Status_Control _CORE_mutex_Seize_no_protocol_slow(
   Thread_queue_Context          *queue_context
 );
 
-Status_Control _CORE_mutex_Surrender(
+Status_Control _CORE_mutex_Surrender_slow(
   CORE_mutex_Control   *the_mutex,
+  Thread_Control       *executing,
+  Thread_queue_Heads   *heads,
+  bool                  keep_priority,
   Thread_queue_Context *queue_context
 );
 
@@ -306,8 +167,7 @@ RTEMS_INLINE_ROUTINE void _CORE_recursive_mutex_Initialize(
   CORE_recursive_mutex_Control *the_mutex
 )
 {
-  _Thread_queue_Initialize( &the_mutex->Mutex.Wait_queue );
-  the_mutex->Mutex.holder = NULL;
+  _CORE_mutex_Initialize( &the_mutex->Mutex );
   the_mutex->nest_level = 0;
 }
 
@@ -319,6 +179,99 @@ RTEMS_INLINE_ROUTINE Status_Control _CORE_recursive_mutex_Seize_nested(
   return STATUS_SUCCESSFUL;
 }
 
+RTEMS_INLINE_ROUTINE Status_Control _CORE_recursive_mutex_Seize(
+  CORE_recursive_mutex_Control  *the_mutex,
+  Thread_Control                *executing,
+  bool                           wait,
+  Watchdog_Interval              timeout,
+  Status_Control              ( *nested )( CORE_recursive_mutex_Control * ),
+  Thread_queue_Context          *queue_context
+)
+{
+  Thread_Control *owner;
+
+  _CORE_mutex_Acquire_critical( &the_mutex->Mutex, queue_context );
+
+  owner = _CORE_mutex_Get_owner( &the_mutex->Mutex );
+
+  if ( owner == NULL ) {
+    _CORE_mutex_Set_owner( &the_mutex->Mutex, executing );
+    ++executing->resource_count;
+    _CORE_mutex_Release( &the_mutex->Mutex, queue_context );
+    return STATUS_SUCCESSFUL;
+  }
+
+  if ( owner == executing ) {
+    Status_Control status;
+
+    status = ( *nested )( the_mutex );
+    _CORE_mutex_Release( &the_mutex->Mutex, queue_context );
+    return status;
+  }
+
+  return _CORE_mutex_Seize_slow(
+    &the_mutex->Mutex,
+    executing,
+    owner,
+    wait,
+    timeout,
+    queue_context
+  );
+}
+
+RTEMS_INLINE_ROUTINE Status_Control _CORE_recursive_mutex_Surrender(
+  CORE_recursive_mutex_Control *the_mutex,
+  Thread_Control               *executing,
+  Thread_queue_Context         *queue_context
+)
+{
+  unsigned int        nest_level;
+  Thread_queue_Heads *heads;
+  bool                keep_priority;
+
+  _CORE_mutex_Acquire_critical( &the_mutex->Mutex, queue_context );
+
+  if ( !_CORE_mutex_Is_owner( &the_mutex->Mutex, executing ) ) {
+    _CORE_mutex_Release( &the_mutex->Mutex, queue_context );
+    return STATUS_NOT_OWNER;
+  }
+
+  nest_level = the_mutex->nest_level;
+
+  if ( nest_level > 0 ) {
+    the_mutex->nest_level = nest_level - 1;
+    _CORE_mutex_Release( &the_mutex->Mutex, queue_context );
+    return STATUS_SUCCESSFUL;
+  }
+
+  --executing->resource_count;
+  _CORE_mutex_Set_owner( &the_mutex->Mutex, NULL );
+
+  /*
+   * 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 = the_mutex->Mutex.Wait_queue.Queue.heads;
+  keep_priority = _Thread_Owns_resources( executing )
+    || !executing->priority_restore_hint;
+
+  if ( heads == NULL && keep_priority ) {
+    _CORE_mutex_Release( &the_mutex->Mutex, queue_context );
+    return STATUS_SUCCESSFUL;
+  }
+
+  return _CORE_mutex_Surrender_slow(
+    &the_mutex->Mutex,
+    executing,
+    heads,
+    keep_priority,
+    queue_context
+  );
+}
+
 RTEMS_INLINE_ROUTINE Status_Control _CORE_recursive_mutex_Seize_no_protocol(
   CORE_recursive_mutex_Control  *the_mutex,
   const Thread_queue_Operations *operations,
diff --git a/cpukit/score/src/apimutex.c b/cpukit/score/src/apimutex.c
index e3c6e5a705..ed5cfd5831 100644
--- a/cpukit/score/src/apimutex.c
+++ b/cpukit/score/src/apimutex.c
@@ -47,16 +47,12 @@ void _API_Mutex_Allocate(
 {
   API_Mutex_Control *mutex;
 
-  CORE_mutex_Attributes attr =  {
-    CORE_MUTEX_NESTING_ACQUIRES
-  };
-
   mutex = (API_Mutex_Control *)
     _Objects_Allocate_unprotected( &_API_Mutex_Information );
 
   _Assert( mutex != NULL );
 
-  _CORE_mutex_Initialize( &mutex->Mutex, NULL, &attr, false );
+  _CORE_recursive_mutex_Initialize( &mutex->Mutex );
 
   _Objects_Open_u32( &_API_Mutex_Information, &mutex->Object, 1 );
 
diff --git a/cpukit/score/src/apimutexisowner.c b/cpukit/score/src/apimutexisowner.c
index a80c664cb3..65b80ed5b3 100644
--- a/cpukit/score/src/apimutexisowner.c
+++ b/cpukit/score/src/apimutexisowner.c
@@ -18,9 +18,13 @@
 #endif
 
 #include <rtems/score/apimutex.h>
+#include <rtems/score/coremuteximpl.h>
 #include <rtems/score/threadimpl.h>
 
 bool _API_Mutex_Is_owner( const API_Mutex_Control *the_mutex )
 {
-  return the_mutex->Mutex.holder == _Thread_Get_executing();
+  return _CORE_mutex_Is_owner(
+    &the_mutex->Mutex.Mutex,
+    _Thread_Get_executing()
+  );
 }
diff --git a/cpukit/score/src/apimutexlock.c b/cpukit/score/src/apimutexlock.c
index 7a7f911f84..df53e75256 100644
--- a/cpukit/score/src/apimutexlock.c
+++ b/cpukit/score/src/apimutexlock.c
@@ -34,15 +34,16 @@ void _API_Mutex_Lock( API_Mutex_Control *the_mutex )
   _Thread_queue_Context_initialize( &queue_context );
   _ISR_lock_ISR_disable( &queue_context.Lock_context );
 
-  _CORE_mutex_Seize(
+  _CORE_recursive_mutex_Seize(
     &the_mutex->Mutex,
     _Thread_Executing,
     true,
-    0,
+    WATCHDOG_NO_TIMEOUT,
+    _CORE_recursive_mutex_Seize_nested,
     &queue_context
   );
 
-  if ( the_mutex->Mutex.nest_count == 1 ) {
+  if ( the_mutex->Mutex.nest_level == 0 ) {
     the_mutex->previous_thread_life_state = previous_thread_life_state;
   }
 }
diff --git a/cpukit/score/src/apimutexunlock.c b/cpukit/score/src/apimutexunlock.c
index 486301fa82..67188db144 100644
--- a/cpukit/score/src/apimutexunlock.c
+++ b/cpukit/score/src/apimutexunlock.c
@@ -29,11 +29,15 @@ void _API_Mutex_Unlock( API_Mutex_Control *the_mutex )
   bool                 restore_thread_life_protection;
 
   previous_thread_life_state = the_mutex->previous_thread_life_state;
-  restore_thread_life_protection = the_mutex->Mutex.nest_count == 1;
+  restore_thread_life_protection = the_mutex->Mutex.nest_level == 0;
 
   _Thread_queue_Context_initialize( &queue_context );
   _ISR_lock_ISR_disable( &queue_context.Lock_context );
-  _CORE_mutex_Surrender( &the_mutex->Mutex, &queue_context );
+  _CORE_recursive_mutex_Surrender(
+    &the_mutex->Mutex,
+    _Thread_Executing,
+    &queue_context
+  );
 
   if ( restore_thread_life_protection ) {
     _Thread_Set_life_protection( previous_thread_life_state );
diff --git a/cpukit/score/src/coremutex.c b/cpukit/score/src/coremutex.c
deleted file mode 100644
index 9c6b7a8b93..0000000000
--- a/cpukit/score/src/coremutex.c
+++ /dev/null
@@ -1,53 +0,0 @@
-/**
- *  @file
- *
- *  @brief Initialize a Core Mutex
- *  @ingroup ScoreMutex
- */
-
-/*
- *  COPYRIGHT (c) 1989-1999.
- *  On-Line Applications Research Corporation (OAR).
- *
- *  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.
- */
-
-#if HAVE_CONFIG_H
-#include "config.h"
-#endif
-
-#include <rtems/system.h>
-#include <rtems/score/isr.h>
-#include <rtems/score/coremuteximpl.h>
-#include <rtems/score/thread.h>
-
-Status_Control _CORE_mutex_Initialize(
-  CORE_mutex_Control           *the_mutex,
-  Thread_Control               *executing,
-  const CORE_mutex_Attributes  *the_mutex_attributes,
-  bool                          initially_locked
-)
-{
-
-/* Add this to the RTEMS environment later ?????????
-  rtems_assert( initial_lock == CORE_MUTEX_LOCKED ||
-                initial_lock == CORE_MUTEX_UNLOCKED );
- */
-
-  the_mutex->Attributes    = *the_mutex_attributes;
-
-  if ( initially_locked ) {
-    the_mutex->nest_count = 1;
-    the_mutex->holder     = executing;
-    executing->resource_count++;
-  } else {
-    the_mutex->nest_count = 0;
-    the_mutex->holder     = NULL;
-  }
-
-  _Thread_queue_Initialize( &the_mutex->Wait_queue );
-
-  return STATUS_SUCCESSFUL;
-}
diff --git a/cpukit/score/src/coremutexseize.c b/cpukit/score/src/coremutexseize.c
index ed5eb0aeec..ab743c4847 100644
--- a/cpukit/score/src/coremutexseize.c
+++ b/cpukit/score/src/coremutexseize.c
@@ -22,14 +22,19 @@
 #include <rtems/score/statesimpl.h>
 #include <rtems/score/thread.h>
 
-Status_Control _CORE_mutex_Seize_interrupt_blocking(
+Status_Control _CORE_mutex_Seize_slow(
   CORE_mutex_Control   *the_mutex,
   Thread_Control       *executing,
+  Thread_Control       *owner,
+  bool                  wait,
   Watchdog_Interval     timeout,
   Thread_queue_Context *queue_context
 )
 {
-  Thread_Control *holder;
+  if ( !wait ) {
+    _CORE_mutex_Release( the_mutex, queue_context );
+    return STATUS_UNAVAILABLE;
+  }
 
 #if !defined(RTEMS_SMP)
   /*
@@ -37,23 +42,19 @@ Status_Control _CORE_mutex_Seize_interrupt_blocking(
    * priority inheritance mutexes.
    */
   _Thread_Dispatch_disable();
-#endif
-
-  holder = the_mutex->holder;
 
-#if !defined(RTEMS_SMP)
   /*
    * To enable interrupts here works only since exactly one executing thread
    * exists and only threads are allowed to seize and surrender mutexes with
    * the priority inheritance protocol.  On SMP configurations more than one
    * executing thread may exist, so here we must not release the lock, since
-   * otherwise the current holder may be no longer the holder of the mutex
+   * otherwise the current owner may be no longer the owner of the mutex
    * once we released the lock.
    */
   _CORE_mutex_Release( the_mutex, queue_context );
 #endif
 
-  _Thread_Inherit_priority( holder, executing );
+  _Thread_Inherit_priority( owner, executing );
 
 #if defined(RTEMS_SMP)
   _Thread_queue_Context_set_expected_level( queue_context, 1 );
diff --git a/cpukit/score/src/coremutexsurrender.c b/cpukit/score/src/coremutexsurrender.c
index 5075e204c9..6604be89da 100644
--- a/cpukit/score/src/coremutexsurrender.c
+++ b/cpukit/score/src/coremutexsurrender.c
@@ -18,141 +18,58 @@
 #include "config.h"
 #endif
 
-#include <rtems/system.h>
-#include <rtems/score/isr.h>
 #include <rtems/score/coremuteximpl.h>
-#include <rtems/score/thread.h>
 
-Status_Control _CORE_mutex_Surrender(
+Status_Control _CORE_mutex_Surrender_slow(
   CORE_mutex_Control   *the_mutex,
+  Thread_Control       *executing,
+  Thread_queue_Heads   *heads,
+  bool                  keep_priority,
   Thread_queue_Context *queue_context
 )
 {
-  Thread_Control *the_thread;
-  Thread_Control *holder;
+  if ( heads != NULL ) {
+    const Thread_queue_Operations *operations;
+    Thread_Control                *new_owner;
+    bool                           unblock;
 
-  holder = the_mutex->holder;
+    operations = CORE_MUTEX_TQ_OPERATIONS;
+    new_owner = ( *operations->first )( heads );
 
-  /*
-   *  Priority Ceiling or Priority Inheritance mutexes must be released by the
-   *  thread which acquired them.
-   */
-  if ( !_Thread_Is_executing( holder ) ) {
-    _ISR_lock_ISR_enable( &queue_context->Lock_context );
-    return STATUS_NOT_OWNER;
-  }
-
-  _CORE_mutex_Acquire_critical( the_mutex, queue_context );
-
-  /* XXX already unlocked -- not right status */
-
-  if ( !the_mutex->nest_count ) {
-    _CORE_mutex_Release( the_mutex, queue_context );
-    return STATUS_SUCCESSFUL;
-  }
-
-  the_mutex->nest_count--;
+    _CORE_mutex_Set_owner( the_mutex, new_owner );
 
-  if ( the_mutex->nest_count != 0 ) {
-    /*
-     *  All error checking is on the locking side, so if the lock was
-     *  allowed to acquired multiple times, then we should just deal with
-     *  that.  The RTEMS_DEBUG is just a validation.
-     */
-    #if defined(RTEMS_DEBUG)
-      switch ( the_mutex->Attributes.lock_nesting_behavior ) {
-        case CORE_MUTEX_NESTING_ACQUIRES:
-          _CORE_mutex_Release( the_mutex, queue_context );
-          return STATUS_SUCCESSFUL;
-        #if defined(RTEMS_POSIX_API)
-          case CORE_MUTEX_NESTING_IS_ERROR:
-            /* should never occur */
-            _CORE_mutex_Release( the_mutex, queue_context );
-            return STATUS_NESTING_NOT_ALLOWED;
-        #endif
-      }
-    #else
-      _CORE_mutex_Release( the_mutex, queue_context );
-      /* must be CORE_MUTEX_NESTING_ACQUIRES or we wouldn't be here */
-      return STATUS_SUCCESSFUL;
-    #endif
-  }
-
-  /*
-   *  Formally release the mutex before possibly transferring it to a
-   *  blocked thread.
-   */
-   holder->resource_count--;
-  the_mutex->holder = NULL;
-
-  /*
-   *  Now we check if another thread was waiting for this mutex.  If so,
-   *  transfer the mutex to that thread.
-   */
-  if (
-    ( the_thread = _Thread_queue_First_locked(
-        &the_mutex->Wait_queue,
-        CORE_MUTEX_TQ_OPERATIONS
-      )
-    )
-  ) {
-    bool unblock;
-
-    the_mutex->holder     = the_thread;
-    the_mutex->nest_count = 1;
-
-    /*
-     * We must extract the thread now since this will restore its default
-     * thread lock.  This is necessary to avoid a deadlock in the
-     * _Thread_Change_priority() below due to a recursive thread queue lock
-     * acquire.
-     */
     unblock = _Thread_queue_Extract_locked(
       &the_mutex->Wait_queue.Queue,
-      CORE_MUTEX_TQ_OPERATIONS,
-      the_thread,
+      operations,
+      new_owner,
       queue_context
     );
 
 #if defined(RTEMS_MULTIPROCESSING)
-    if ( _Objects_Is_local_id( the_thread->Object.id ) )
+    if ( _Objects_Is_local_id( new_owner->Object.id ) )
 #endif
     {
-      the_thread->resource_count++;
-      _Thread_queue_Boost_priority( &the_mutex->Wait_queue.Queue, the_thread );
+      ++new_owner->resource_count;
+      _Thread_queue_Boost_priority( &the_mutex->Wait_queue.Queue, new_owner );
     }
 
     _Thread_queue_Unblock_critical(
       unblock,
       &the_mutex->Wait_queue.Queue,
-      the_thread,
+      new_owner,
       &queue_context->Lock_context
     );
   } else {
     _CORE_mutex_Release( the_mutex, queue_context );
   }
 
-  /*
-   *  Whether or not someone is waiting for the mutex, an
-   *  inherited priority must be lowered if this is the last
-   *  mutex (i.e. resource) this task has.
-   */
-  if ( !_Thread_Owns_resources( holder ) ) {
-    /*
-     * Ensure that the holder resource count is visible to all other processors
-     * and that we read the latest priority restore hint.
-     */
-    _Atomic_Fence( ATOMIC_ORDER_ACQ_REL );
-
-    if ( holder->priority_restore_hint ) {
-      Per_CPU_Control *cpu_self;
+  if ( !keep_priority ) {
+    Per_CPU_Control *cpu_self;
 
-      cpu_self = _Thread_Dispatch_disable();
-      _Thread_Restore_priority( holder );
-      _Thread_Dispatch_enable( cpu_self );
-    }
+    cpu_self = _Thread_Dispatch_disable();
+    _Thread_Restore_priority( executing );
+    _Thread_Dispatch_enable( cpu_self );
   }
 
-  _CORE_mutex_Restore_priority( holder );
   return STATUS_SUCCESSFUL;
 }
diff --git a/cpukit/score/src/debugisownerofallocator.c b/cpukit/score/src/debugisownerofallocator.c
index 57da2ca001..6b396df4fc 100644
--- a/cpukit/score/src/debugisownerofallocator.c
+++ b/cpukit/score/src/debugisownerofallocator.c
@@ -27,7 +27,7 @@
     bool owner;
 
     if ( mutex != NULL ) {
-      owner = mutex->Mutex.holder == _Thread_Get_executing();
+      owner = _API_Mutex_Is_owner( mutex );
     } else {
       owner = false;
     }