2008-01-22 Joel Sherrill <joel.sherrill@oarcorp.com>

	* rtems/include/rtems/rtems/event.h,
	rtems/inline/rtems/rtems/eventset.inl, rtems/src/event.c,
	rtems/src/eventseize.c, rtems/src/eventsurrender.c,
	rtems/src/eventtimeout.c, score/Makefile.am, score/preinstall.am,
	score/include/rtems/score/interr.h,
	score/include/rtems/score/thread.h,
	score/include/rtems/score/threadq.h,
	score/include/rtems/score/tqdata.h,
	score/inline/rtems/score/threadq.inl,
	score/inline/rtems/score/tqdata.inl, score/src/threadq.c,
	score/src/threadqdequeue.c, score/src/threadqdequeuefifo.c,
	score/src/threadqdequeuepriority.c, score/src/threadqenqueue.c,
	score/src/threadqenqueuefifo.c, score/src/threadqenqueuepriority.c,
	score/src/threadqextract.c, score/src/threadqextractfifo.c,
	score/src/threadqextractpriority.c,
	score/src/threadqextractwithproxy.c, score/src/threadqfirst.c,
	score/src/threadqfirstfifo.c, score/src/threadqfirstpriority.c,
	score/src/threadqflush.c, score/src/threadqrequeue.c,
	score/src/threadqtimeout.c: Refactor thread queue enqueue and event
	blocking synchronization critical sections. This resulted in three
	copies of essentially the same hard to test critical section code
	becoming the one shared routine _Thread_blocking_operation_Cancel. In
	addition, the thread queue and event code now share a common
	synchronization enumerated type. Along the way, switches were
	reworked to eliminate dead code generated by gcc and comments and
	copyrights were updated.
	* score/include/rtems/score/threadsync.h,
	score/src/threadblockingoperationcancel.c: New files.

27 files changed, 318 insertions, 216 deletions

diff --git a/cpukit/score/Makefile.am b/cpukit/score/Makefile.am
index 3446062f6b..3440af7090 100644
--- a/cpukit/score/Makefile.am
+++ b/cpukit/score/Makefile.am
@@ -28,10 +28,11 @@ include_rtems_score_HEADERS = include/rtems/score/address.h \
     include/rtems/score/object.h include/rtems/score/priority.h \
     include/rtems/score/stack.h include/rtems/score/states.h \
     include/rtems/score/sysstate.h include/rtems/score/thread.h \
-    include/rtems/score/threadq.h include/rtems/score/timespec.h \
-    include/rtems/score/tod.h include/rtems/score/tqdata.h \
-    include/rtems/score/userext.h include/rtems/score/watchdog.h \
-    include/rtems/score/wkspace.h include/rtems/score/cpuopts.h
+    include/rtems/score/threadq.h include/rtems/score/threadsync.h \
+    include/rtems/score/timespec.h include/rtems/score/tod.h \
+    include/rtems/score/tqdata.h include/rtems/score/userext.h \
+    include/rtems/score/watchdog.h include/rtems/score/wkspace.h \
+    include/rtems/score/cpuopts.h
 
 if HAS_MP
 # We only build multiprocessing related files if HAS_MP was defined
@@ -142,7 +143,8 @@ libscore_a_SOURCES += src/thread.c src/threadchangepriority.c \
     src/threadsettransient.c src/threadstackallocate.c \
     src/threadstackfree.c src/threadstart.c src/threadstartmultitasking.c \
     src/threadsuspend.c src/threadtickletimeslice.c \
-    src/threadyieldprocessor.c src/iterateoverthreads.c
+    src/threadyieldprocessor.c src/iterateoverthreads.c \
+    src/threadblockingoperationcancel.c
 
 ## THREAD_C_FILES only used by ITRON API
 if LIBITRON
diff --git a/cpukit/score/include/rtems/score/interr.h b/cpukit/score/include/rtems/score/interr.h
index 323bc06818..a8792c334b 100644
--- a/cpukit/score/include/rtems/score/interr.h
+++ b/cpukit/score/include/rtems/score/interr.h
@@ -63,7 +63,8 @@ typedef enum {
   INTERNAL_ERROR_INVALID_GLOBAL_ID,
   INTERNAL_ERROR_BAD_STACK_HOOK,
   INTERNAL_ERROR_BAD_ATTRIBUTES,
-  INTERNAL_ERROR_IMPLEMENTATION_KEY_CREATE_INCONSISTENCY
+  INTERNAL_ERROR_IMPLEMENTATION_KEY_CREATE_INCONSISTENCY,
+  INTERNAL_ERROR_IMPLEMENTATION_BLOCKING_OPERATION_CANCEL
 } Internal_errors_Core_list;
 
 /**
diff --git a/cpukit/score/include/rtems/score/thread.h b/cpukit/score/include/rtems/score/thread.h
index 9b9f324b9e..fcf26c9507 100644
--- a/cpukit/score/include/rtems/score/thread.h
+++ b/cpukit/score/include/rtems/score/thread.h
@@ -6,7 +6,7 @@
  */
 
 /*
- *  COPYRIGHT (c) 1989-2007.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
@@ -785,6 +785,27 @@ Thread_Control *_Thread_Get (
   Objects_Locations *location
 );
 
+/**
+ *  @brief Cancel a blocking operation due to ISR
+ *
+ *  This method is used to cancel a blocking operation that was
+ *  satisfied from an ISR while the thread executing was in the
+ *  process of blocking.
+ *
+ *  @param[in] sync_state is the synchronization state
+ *  @param[in] the_thread is the thread whose blocking is canceled
+ *  @param[in] level is the previous ISR disable level
+ *
+ *  @note This is a rare routine in RTEMS.  It is called with
+ *        interrupts disabled and only when an ISR completed
+ *        a blocking condition in process.
+ */
+void _Thread_blocking_operation_Cancel(
+  Thread_blocking_operation_States  sync_state,
+  Thread_Control                   *the_thread,
+  ISR_Level                         level
+);
+
 #ifndef __RTEMS_APPLICATION__
 #include <rtems/score/thread.inl>
 #endif
diff --git a/cpukit/score/include/rtems/score/threadq.h b/cpukit/score/include/rtems/score/threadq.h
index 7b609285eb..2345087c04 100644
--- a/cpukit/score/include/rtems/score/threadq.h
+++ b/cpukit/score/include/rtems/score/threadq.h
@@ -6,7 +6,7 @@
  */
 
 /*
- *  COPYRIGHT (c) 1989-2006.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
@@ -178,9 +178,10 @@ Thread_Control *_Thread_queue_Dequeue_priority(
  *  the_thread_queue with an optional timeout using the
  *  priority discipline.
  */
-void _Thread_queue_Enqueue_priority(
+Thread_blocking_operation_States _Thread_queue_Enqueue_priority (
   Thread_queue_Control *the_thread_queue,
-  Thread_Control       *the_thread
+  Thread_Control       *the_thread,
+  ISR_Level            *level_p
 );
 
 /** @brief  Thread queue Extract priority Helper
@@ -230,9 +231,10 @@ Thread_Control *_Thread_queue_Dequeue_fifo(
  *  the_thread_queue with an optional timeout using the
  *  FIFO discipline.
  */
-void _Thread_queue_Enqueue_fifo(
+Thread_blocking_operation_States _Thread_queue_Enqueue_fifo (
   Thread_queue_Control *the_thread_queue,
-  Thread_Control       *the_thread
+  Thread_Control       *the_thread,
+  ISR_Level            *level_p
 );
 
 /** @brief  Thread queue Extract FIFO
diff --git a/cpukit/score/include/rtems/score/threadsync.h b/cpukit/score/include/rtems/score/threadsync.h
new file mode 100644
index 0000000000..6902f7b33b
--- /dev/null
+++ b/cpukit/score/include/rtems/score/threadsync.h
@@ -0,0 +1,58 @@
+/** 
+ *  @file  rtems/score/threadsync.h
+ *
+ *  This include file contains all constants and structures associated
+ *  with synchronizing a thread blocking operation with potential 
+ *  actions in an ISR.
+ */
+
+/*
+ *  COPYRIGHT (c) 1989-2008.
+ *  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.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#ifndef _RTEMS_SCORE_THREAD_SYNC_H
+#define _RTEMS_SCORE_THREAD_SYNC_H
+
+/**
+ *  @defgroup ScoreThread Thread Blocking Operation Synchronization Handler
+ *
+ *  This handler encapsulates functionality related to the management of
+ *  synchronization critical sections during blocking operations.
+ */
+/**@{*/
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ *  The following enumerated types indicate what happened while the thread
+ *  blocking was in the synchronization window.
+ */
+typedef enum {
+  THREAD_BLOCKING_OPERATION_SYNCHRONIZED,
+  THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED,
+  THREAD_BLOCKING_OPERATION_TIMEOUT,
+  THREAD_BLOCKING_OPERATION_SATISFIED
+}  Thread_blocking_operation_States;
+
+/*
+ *  Operations require a thread pointer so they are prototyped
+ *  in thread.h
+ */
+
+#ifdef __cplusplus
+}
+#endif
+
+/**@}*/
+
+#endif
+/* end of include file */
diff --git a/cpukit/score/include/rtems/score/tqdata.h b/cpukit/score/include/rtems/score/tqdata.h
index b70124ff9e..5b7ce98a03 100644
--- a/cpukit/score/include/rtems/score/tqdata.h
+++ b/cpukit/score/include/rtems/score/tqdata.h
@@ -6,7 +6,7 @@
  */
 
 /*
- *  COPYRIGHT (c) 1989-2006.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
@@ -35,6 +35,7 @@ extern "C" {
 #include <rtems/score/chain.h>
 #include <rtems/score/priority.h>
 #include <rtems/score/states.h>
+#include <rtems/score/threadsync.h>
 
 /**
  *  The following enumerated type details all of the disciplines
@@ -46,17 +47,6 @@ typedef enum {
 }   Thread_queue_Disciplines;
 
 /**
- *  The following enumerated types indicate what happened while the thread
- *  queue was in the synchronization window.
- */
-typedef enum {
-  THREAD_QUEUE_SYNCHRONIZED,
-  THREAD_QUEUE_NOTHING_HAPPENED,
-  THREAD_QUEUE_TIMEOUT,
-  THREAD_QUEUE_SATISFIED
-}  Thread_queue_States;
-
-/**
  *  This is one of the constants used to manage the priority queues.
  *
  *  There are four chains used to maintain a priority -- each chain
@@ -99,7 +89,7 @@ typedef struct {
     Chain_Control Priority[TASK_QUEUE_DATA_NUMBER_OF_PRIORITY_HEADERS];
   } Queues;
   /** This field is used to manage the critical section. */
-  Thread_queue_States      sync_state;
+  Thread_blocking_operation_States sync_state;
   /** This field indicates the thread queue's blocking discipline. */
   Thread_queue_Disciplines discipline;
   /** This indicates the blocking state for threads waiting on this
diff --git a/cpukit/score/inline/rtems/score/threadq.inl b/cpukit/score/inline/rtems/score/threadq.inl
index ccbb928849..5e0d921ac8 100644
--- a/cpukit/score/inline/rtems/score/threadq.inl
+++ b/cpukit/score/inline/rtems/score/threadq.inl
@@ -6,7 +6,7 @@
  */
 
 /*
- *  COPYRIGHT (c) 1989-2006.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
@@ -55,10 +55,12 @@ static inline void _Thread_queue_Process_timeout(
    *  a timeout is not allowed to occur.
    */
 
-  if ( the_thread_queue->sync_state != THREAD_QUEUE_SYNCHRONIZED &&
+  if ( the_thread_queue->sync_state != THREAD_BLOCKING_OPERATION_SYNCHRONIZED &&
        _Thread_Is_executing( the_thread ) ) {
-    if ( the_thread_queue->sync_state != THREAD_QUEUE_SATISFIED )
-      the_thread_queue->sync_state = THREAD_QUEUE_TIMEOUT;
+    if ( the_thread_queue->sync_state != THREAD_BLOCKING_OPERATION_SATISFIED ) {
+      the_thread->Wait.return_code = the_thread->Wait.queue->timeout_status;
+      the_thread_queue->sync_state = THREAD_BLOCKING_OPERATION_TIMEOUT;
+    }
   } else {
     the_thread->Wait.return_code = the_thread->Wait.queue->timeout_status;
     _Thread_queue_Extract( the_thread->Wait.queue, the_thread );
diff --git a/cpukit/score/inline/rtems/score/tqdata.inl b/cpukit/score/inline/rtems/score/tqdata.inl
index d1248f4b74..b063998f8e 100644
--- a/cpukit/score/inline/rtems/score/tqdata.inl
+++ b/cpukit/score/inline/rtems/score/tqdata.inl
@@ -6,7 +6,7 @@
  */
 
 /*
- *  COPYRIGHT (c) 1989-2006.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
@@ -58,7 +58,7 @@ RTEMS_INLINE_ROUTINE void _Thread_queue_Enter_critical_section (
   Thread_queue_Control *the_thread_queue
 )
 {
-  the_thread_queue->sync_state = THREAD_QUEUE_NOTHING_HAPPENED;
+  the_thread_queue->sync_state = THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED;
 }
 
 /**
diff --git a/cpukit/score/preinstall.am b/cpukit/score/preinstall.am
index 040616aa6a..cb27e47d48 100644
--- a/cpukit/score/preinstall.am
+++ b/cpukit/score/preinstall.am
@@ -131,6 +131,10 @@ $(PROJECT_INCLUDE)/rtems/score/threadq.h: include/rtems/score/threadq.h $(PROJEC
 	$(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/threadq.h
 PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/threadq.h
 
+$(PROJECT_INCLUDE)/rtems/score/threadsync.h: include/rtems/score/threadsync.h $(PROJECT_INCLUDE)/rtems/score/$(dirstamp)
+	$(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/threadsync.h
+PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/threadsync.h
+
 $(PROJECT_INCLUDE)/rtems/score/timespec.h: include/rtems/score/timespec.h $(PROJECT_INCLUDE)/rtems/score/$(dirstamp)
 	$(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/timespec.h
 PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/timespec.h
diff --git a/cpukit/score/src/threadblockingoperationcancel.c b/cpukit/score/src/threadblockingoperationcancel.c
new file mode 100644
index 0000000000..b2b7a22745
--- /dev/null
+++ b/cpukit/score/src/threadblockingoperationcancel.c
@@ -0,0 +1,81 @@
+/*
+ *  Cancel Thread Blocking Operation
+ *
+ *
+ *  COPYRIGHT (c) 1989-2007.
+ *  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.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/score/thread.h>
+#if defined(RTEMS_MULTIPROCESSING)
+#include <rtems/score/mpci.h>
+#endif
+
+void _Thread_blocking_operation_Cancel(
+  Thread_blocking_operation_States  sync_state,
+  Thread_Control                   *the_thread,
+  ISR_Level                         level
+)
+{
+  /*
+   *  Cases that should not happen and why.
+   *
+   *  THREAD_BLOCKING_OPERATION_SYNCHRONIZED:
+   *
+   *  This indicates that someone did not enter a blocking
+   *  operation critical section.
+   *
+   *  THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED:
+   *
+   *  This indicates that there was nothing to cancel so
+   *  we should not have been called.
+   */
+
+  #if defined(RTEMS_DEBUG)
+    if ( (sync_state == THREAD_BLOCKING_OPERATION_SYNCHRONIZED)
+         (sync_state == THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED) ) {
+      _Internal_error_Occurred(
+        INTERNAL_ERROR_CORE,
+        TRUE,
+        INTERNAL_ERROR_IMPLEMENTATION_BLOCKING_OPERATION_CANCEL
+      );
+    }
+  #endif
+
+  /*
+   *  If the sync state is timed out, this is very likely not needed.
+   *  But better safe than sorry when it comes to critical sections.
+   */
+  if ( _Watchdog_Is_active( &the_thread->Timer ) ) {
+    _Watchdog_Deactivate( &the_thread->Timer );
+    the_thread->Wait.queue = NULL;
+    _ISR_Enable( level );
+    (void) _Watchdog_Remove( &the_thread->Timer );
+  } else
+    _ISR_Enable( level );
+
+  /*
+   *  Global objects with thread queue's should not be operated on from an
+   *  ISR.  But the sync code still must allow short timeouts to be processed
+   *  correctly.
+   */
+
+  _Thread_Unblock( the_thread );
+
+#if defined(RTEMS_MULTIPROCESSING)
+  if ( !_Objects_Is_local_id( the_thread->Object.id ) )
+    _Thread_MP_Free_proxy( the_thread );
+#endif
+
+}
diff --git a/cpukit/score/src/threadq.c b/cpukit/score/src/threadq.c
index d17c3d8f7e..baa85a13e1 100644
--- a/cpukit/score/src/threadq.c
+++ b/cpukit/score/src/threadq.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-1999.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
@@ -47,23 +47,20 @@ void _Thread_queue_Initialize(
   uint32_t                      timeout_status
 )
 {
-  uint32_t   index;
-
   the_thread_queue->state          = state;
   the_thread_queue->discipline     = the_discipline;
   the_thread_queue->timeout_status = timeout_status;
-  the_thread_queue->sync_state     = THREAD_QUEUE_SYNCHRONIZED;
+  the_thread_queue->sync_state     = THREAD_BLOCKING_OPERATION_SYNCHRONIZED;
+
+  if ( the_discipline == THREAD_QUEUE_DISCIPLINE_PRIORITY ) {
+    uint32_t   index;
 
-  switch ( the_discipline ) {
-    case THREAD_QUEUE_DISCIPLINE_FIFO:
-      _Chain_Initialize_empty( &the_thread_queue->Queues.Fifo );
-      break;
-    case THREAD_QUEUE_DISCIPLINE_PRIORITY:
-      for( index=0 ;
-           index < TASK_QUEUE_DATA_NUMBER_OF_PRIORITY_HEADERS ;
-           index++)
-        _Chain_Initialize_empty( &the_thread_queue->Queues.Priority[index] );
-      break;
+    for( index=0 ;
+         index < TASK_QUEUE_DATA_NUMBER_OF_PRIORITY_HEADERS ;
+         index++)
+      _Chain_Initialize_empty( &the_thread_queue->Queues.Priority[index] );
+  } else { /* must be THREAD_QUEUE_DISCIPLINE_FIFO */
+    _Chain_Initialize_empty( &the_thread_queue->Queues.Fifo );
   }
 
 }
diff --git a/cpukit/score/src/threadqdequeue.c b/cpukit/score/src/threadqdequeue.c
index d5968b0210..160bd6e84c 100644
--- a/cpukit/score/src/threadqdequeue.c
+++ b/cpukit/score/src/threadqdequeue.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-1999.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
@@ -47,19 +47,12 @@ Thread_Control *_Thread_queue_Dequeue(
   Thread_queue_Control *the_thread_queue
 )
 {
-  Thread_Control *the_thread;
+  Thread_Control *(*dequeue_p)( Thread_queue_Control * );
 
-  switch ( the_thread_queue->discipline ) {
-    case THREAD_QUEUE_DISCIPLINE_FIFO:
-      the_thread = _Thread_queue_Dequeue_fifo( the_thread_queue );
-      break;
-    case THREAD_QUEUE_DISCIPLINE_PRIORITY:
-      the_thread = _Thread_queue_Dequeue_priority( the_thread_queue );
-      break;
-    default:              /* this is only to prevent warnings */
-      the_thread = NULL;
-      break;
-  }
+  if ( the_thread_queue->discipline == THREAD_QUEUE_DISCIPLINE_PRIORITY )
+    dequeue_p = _Thread_queue_Dequeue_priority;
+  else /* must be THREAD_QUEUE_DISCIPLINE_FIFO */
+    dequeue_p = _Thread_queue_Dequeue_fifo;
 
-  return( the_thread );
+  return (*dequeue_p)( the_thread_queue );
 }
diff --git a/cpukit/score/src/threadqdequeuefifo.c b/cpukit/score/src/threadqdequeuefifo.c
index 787ec41074..d494b90b85 100644
--- a/cpukit/score/src/threadqdequeuefifo.c
+++ b/cpukit/score/src/threadqdequeuefifo.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-2006.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
@@ -75,14 +75,14 @@ Thread_Control *_Thread_queue_Dequeue_fifo(
   }
 
   switch ( the_thread_queue->sync_state ) {
-    case THREAD_QUEUE_SYNCHRONIZED:
-    case THREAD_QUEUE_SATISFIED:
+    case THREAD_BLOCKING_OPERATION_SYNCHRONIZED:
+    case THREAD_BLOCKING_OPERATION_SATISFIED:
       _ISR_Enable( level );
       return NULL;
 
-    case THREAD_QUEUE_NOTHING_HAPPENED:
-    case THREAD_QUEUE_TIMEOUT:
-      the_thread_queue->sync_state = THREAD_QUEUE_SATISFIED;
+    case THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED:
+    case THREAD_BLOCKING_OPERATION_TIMEOUT:
+      the_thread_queue->sync_state = THREAD_BLOCKING_OPERATION_SATISFIED;
       _ISR_Enable( level );
       return _Thread_Executing;
   }
diff --git a/cpukit/score/src/threadqdequeuepriority.c b/cpukit/score/src/threadqdequeuepriority.c
index 4da18165d9..d9aa1b14f8 100644
--- a/cpukit/score/src/threadqdequeuepriority.c
+++ b/cpukit/score/src/threadqdequeuepriority.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-2006.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
@@ -55,6 +55,7 @@ Thread_Control *_Thread_queue_Dequeue_priority(
   Chain_Node     *last_node;
   Chain_Node     *next_node;
   Chain_Node     *previous_node;
+  Thread_blocking_operation_States sync;
 
   _ISR_Disable( level );
   for( index=0 ;
@@ -67,17 +68,21 @@ Thread_Control *_Thread_queue_Dequeue_priority(
     }
   }
 
-  switch ( the_thread_queue->sync_state ) {
-    case THREAD_QUEUE_SYNCHRONIZED:
-    case THREAD_QUEUE_SATISFIED:
-      _ISR_Enable( level );
-      return NULL;
+  /*
+   * If we interrupted a blocking operation, cancel it.
+   */
+  sync = the_thread_queue->sync_state;
+  if ( (sync == THREAD_BLOCKING_OPERATION_SYNCHRONIZED) ||
+       (sync == THREAD_BLOCKING_OPERATION_SATISFIED) ) {
+    _ISR_Enable( level );
+    return NULL;
+  }
 
-    case THREAD_QUEUE_NOTHING_HAPPENED:
-    case THREAD_QUEUE_TIMEOUT:
-      the_thread_queue->sync_state = THREAD_QUEUE_SATISFIED;
-      _ISR_Enable( level );
-      return _Thread_Executing;
+  if ( (sync == THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED) ||
+       (sync == THREAD_BLOCKING_OPERATION_TIMEOUT ) ) {
+    the_thread_queue->sync_state = THREAD_BLOCKING_OPERATION_SATISFIED;
+    _ISR_Enable( level );
+    return _Thread_Executing;
   }
 
 dequeue:
diff --git a/cpukit/score/src/threadqenqueue.c b/cpukit/score/src/threadqenqueue.c
index 2cc1141993..688962950a 100644
--- a/cpukit/score/src/threadqenqueue.c
+++ b/cpukit/score/src/threadqenqueue.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-2006.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
@@ -51,7 +51,14 @@ void _Thread_queue_Enqueue_with_handler(
   Thread_queue_Timeout_callout  handler
 )
 {
-  Thread_Control *the_thread;
+  Thread_Control                   *the_thread;
+  ISR_Level                         level;
+  Thread_blocking_operation_States  sync_state;
+  Thread_blocking_operation_States (*enqueue_p)(
+    Thread_queue_Control *,
+    Thread_Control *,
+    ISR_Level *
+  );
 
   the_thread = _Thread_Executing;
 
@@ -82,12 +89,12 @@ void _Thread_queue_Enqueue_with_handler(
   /*
    *  Now enqueue the thread per the discipline for this thread queue.
    */ 
-  switch( the_thread_queue->discipline ) {
-    case THREAD_QUEUE_DISCIPLINE_FIFO:
-      _Thread_queue_Enqueue_fifo( the_thread_queue, the_thread );
-      break;
-    case THREAD_QUEUE_DISCIPLINE_PRIORITY:
-      _Thread_queue_Enqueue_priority( the_thread_queue, the_thread );
-      break;
-  }
+  if ( the_thread_queue->discipline == THREAD_QUEUE_DISCIPLINE_PRIORITY )
+    enqueue_p = _Thread_queue_Enqueue_priority;
+  else /* must be THREAD_QUEUE_DISCIPLINE_FIFO */
+    enqueue_p = _Thread_queue_Enqueue_fifo;
+
+  sync_state = (*enqueue_p)( the_thread_queue, the_thread, &level );
+  if ( sync_state != THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED )
+    _Thread_blocking_operation_Cancel( sync_state, the_thread, level );
 }
diff --git a/cpukit/score/src/threadqenqueuefifo.c b/cpukit/score/src/threadqenqueuefifo.c
index c7260807ed..229261efad 100644
--- a/cpukit/score/src/threadqenqueuefifo.c
+++ b/cpukit/score/src/threadqenqueuefifo.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-1999.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
@@ -41,64 +41,38 @@
  *    only case
  */
 
-void _Thread_queue_Enqueue_fifo (
+Thread_blocking_operation_States _Thread_queue_Enqueue_fifo (
   Thread_queue_Control *the_thread_queue,
-  Thread_Control       *the_thread
+  Thread_Control       *the_thread,
+  ISR_Level            *level_p
 )
 {
-  ISR_Level            level;
-  Thread_queue_States  sync_state;
+  Thread_blocking_operation_States sync_state;
+  ISR_Level                        level;
 
   _ISR_Disable( level );
 
-  sync_state = the_thread_queue->sync_state;
-  the_thread_queue->sync_state = THREAD_QUEUE_SYNCHRONIZED;
-
-  switch ( sync_state ) {
-    case THREAD_QUEUE_SYNCHRONIZED:
-      /*
-       *  This should never happen.  It indicates that someone did not
-       *  enter a thread queue critical section.
-       */
-      break;
-
-    case THREAD_QUEUE_NOTHING_HAPPENED:
+    sync_state = the_thread_queue->sync_state;
+    the_thread_queue->sync_state = THREAD_BLOCKING_OPERATION_SYNCHRONIZED;
+    if (sync_state == THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED) {
       _Chain_Append_unprotected(
         &the_thread_queue->Queues.Fifo,
         &the_thread->Object.Node
       );
       the_thread->Wait.queue = the_thread_queue;
-      _ISR_Enable( level );
-      return;
 
-    case THREAD_QUEUE_TIMEOUT:
-      the_thread->Wait.return_code = the_thread->Wait.queue->timeout_status;
-      the_thread->Wait.queue = NULL;
+      the_thread_queue->sync_state = THREAD_BLOCKING_OPERATION_SYNCHRONIZED;
       _ISR_Enable( level );
-      break;
-
-    case THREAD_QUEUE_SATISFIED:
-      if ( _Watchdog_Is_active( &the_thread->Timer ) ) {
-        _Watchdog_Deactivate( &the_thread->Timer );
-      the_thread->Wait.queue = NULL;
-        _ISR_Enable( level );
-        (void) _Watchdog_Remove( &the_thread->Timer );
-      } else
-        _ISR_Enable( level );
-      break;
-  }
-
+      return THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED;
+    }
+      
   /*
-   *  Global objects with thread queue's should not be operated on from an
-   *  ISR.  But the sync code still must allow short timeouts to be processed
-   *  correctly.
+   *  An interrupt completed the thread's blocking request.
+   *  For example, the blocking thread could have been given
+   *  the mutex by an ISR or timed out.
+   *
+   *  WARNING! Returning with interrupts disabled!
    */
-
-  _Thread_Unblock( the_thread );
-
-#if defined(RTEMS_MULTIPROCESSING)
-  if ( !_Objects_Is_local_id( the_thread->Object.id ) )
-    _Thread_MP_Free_proxy( the_thread );
-#endif
-
+  *level_p = level;
+  return sync_state;
 }
diff --git a/cpukit/score/src/threadqenqueuepriority.c b/cpukit/score/src/threadqenqueuepriority.c
index 9974a3a674..cad998cf87 100644
--- a/cpukit/score/src/threadqenqueuepriority.c
+++ b/cpukit/score/src/threadqenqueuepriority.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-1999.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
@@ -42,9 +42,10 @@
  *    forward equal
  */
 
-void _Thread_queue_Enqueue_priority(
+Thread_blocking_operation_States _Thread_queue_Enqueue_priority (
   Thread_queue_Control *the_thread_queue,
-  Thread_Control       *the_thread
+  Thread_Control       *the_thread,
+  ISR_Level            *level_p
 )
 {
   Priority_Control     search_priority;
@@ -58,7 +59,6 @@ void _Thread_queue_Enqueue_priority(
   Chain_Node          *search_node;
   Priority_Control     priority;
   States_Control       block_state;
-  Thread_queue_States  sync_state;
 
   _Chain_Initialize_empty( &the_thread->Wait.Block2n );
 
@@ -96,10 +96,11 @@ restart_forward_search:
        (Thread_Control *)search_thread->Object.Node.next;
   }
 
-  if ( the_thread_queue->sync_state != THREAD_QUEUE_NOTHING_HAPPENED )
+  if ( the_thread_queue->sync_state !=
+       THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED )
     goto synchronize;
 
-  the_thread_queue->sync_state = THREAD_QUEUE_SYNCHRONIZED;
+  the_thread_queue->sync_state = THREAD_BLOCKING_OPERATION_SYNCHRONIZED;
 
   if ( priority == search_priority )
     goto equal_priority;
@@ -114,7 +115,7 @@ restart_forward_search:
   search_node->previous  = the_node;
   the_thread->Wait.queue = the_thread_queue;
   _ISR_Enable( level );
-  return;
+  return THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED;
 
 restart_reverse_search:
   search_priority     = PRIORITY_MAXIMUM + 1;
@@ -142,10 +143,11 @@ restart_reverse_search:
                          search_thread->Object.Node.previous;
   }
 
-  if ( the_thread_queue->sync_state != THREAD_QUEUE_NOTHING_HAPPENED )
+  if ( the_thread_queue->sync_state !=
+       THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED )
     goto synchronize;
 
-  the_thread_queue->sync_state = THREAD_QUEUE_SYNCHRONIZED;
+  the_thread_queue->sync_state = THREAD_BLOCKING_OPERATION_SYNCHRONIZED;
 
   if ( priority == search_priority )
     goto equal_priority;
@@ -160,7 +162,7 @@ restart_reverse_search:
   next_node->previous    = the_node;
   the_thread->Wait.queue = the_thread_queue;
   _ISR_Enable( level );
-  return;
+  return THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED;
 
 equal_priority:               /* add at end of priority group */
   search_node   = _Chain_Tail( &search_thread->Wait.Block2n );
@@ -173,54 +175,16 @@ equal_priority:               /* add at end of priority group */
   search_node->previous  = the_node;
   the_thread->Wait.queue = the_thread_queue;
   _ISR_Enable( level );
-  return;
+  return THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED;
 
 synchronize:
-
-  sync_state = the_thread_queue->sync_state;
-  the_thread_queue->sync_state = THREAD_QUEUE_SYNCHRONIZED;
-
-  switch ( sync_state ) {
-    case THREAD_QUEUE_SYNCHRONIZED:
-      /*
-       *  This should never happen.  It indicates that someone did not
-       *  enter a thread queue critical section.
-       */
-      break;
-
-    case THREAD_QUEUE_NOTHING_HAPPENED:
-      /*
-       *  This should never happen.  All of this was dealt with above.
-       */
-      break;
-
-    case THREAD_QUEUE_TIMEOUT:
-      the_thread->Wait.return_code = the_thread->Wait.queue->timeout_status;
-      the_thread->Wait.queue = NULL;
-      _ISR_Enable( level );
-      break;
-
-    case THREAD_QUEUE_SATISFIED:
-      if ( _Watchdog_Is_active( &the_thread->Timer ) ) {
-        _Watchdog_Deactivate( &the_thread->Timer );
-        the_thread->Wait.queue = NULL;
-        _ISR_Enable( level );
-        (void) _Watchdog_Remove( &the_thread->Timer );
-      } else
-        _ISR_Enable( level );
-      break;
-  }
-
   /*
-   *  Global objects with thread queue's should not be operated on from an
-   *  ISR.  But the sync code still must allow short timeouts to be processed
-   *  correctly.
+   *  An interrupt completed the thread's blocking request.
+   *  For example, the blocking thread could have been given
+   *  the mutex by an ISR or timed out.
+   *
+   *  WARNING! Returning with interrupts disabled!
    */
-
-  _Thread_Unblock( the_thread );
-
-#if defined(RTEMS_MULTIPROCESSING)
-  if ( !_Objects_Is_local_id( the_thread->Object.id ) )
-    _Thread_MP_Free_proxy( the_thread );
-#endif
+  *level_p = level;
+  return the_thread_queue->sync_state;
 }
diff --git a/cpukit/score/src/threadqextract.c b/cpukit/score/src/threadqextract.c
index a8faef03f7..f971a7b970 100644
--- a/cpukit/score/src/threadqextract.c
+++ b/cpukit/score/src/threadqextract.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-1999.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
diff --git a/cpukit/score/src/threadqextractfifo.c b/cpukit/score/src/threadqextractfifo.c
index f7ecf3e270..7fd6f41d34 100644
--- a/cpukit/score/src/threadqextractfifo.c
+++ b/cpukit/score/src/threadqextractfifo.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-2006.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
diff --git a/cpukit/score/src/threadqextractpriority.c b/cpukit/score/src/threadqextractpriority.c
index ef45fb4423..739e6985c4 100644
--- a/cpukit/score/src/threadqextractpriority.c
+++ b/cpukit/score/src/threadqextractpriority.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-2006.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
diff --git a/cpukit/score/src/threadqextractwithproxy.c b/cpukit/score/src/threadqextractwithproxy.c
index 14653091b3..5c24431ab5 100644
--- a/cpukit/score/src/threadqextractwithproxy.c
+++ b/cpukit/score/src/threadqextractwithproxy.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-1999.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
diff --git a/cpukit/score/src/threadqfirst.c b/cpukit/score/src/threadqfirst.c
index bcbe759eda..9112b0ab72 100644
--- a/cpukit/score/src/threadqfirst.c
+++ b/cpukit/score/src/threadqfirst.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-1999.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
diff --git a/cpukit/score/src/threadqfirstfifo.c b/cpukit/score/src/threadqfirstfifo.c
index b002f1f448..9163780c76 100644
--- a/cpukit/score/src/threadqfirstfifo.c
+++ b/cpukit/score/src/threadqfirstfifo.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-1999.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
diff --git a/cpukit/score/src/threadqfirstpriority.c b/cpukit/score/src/threadqfirstpriority.c
index 81ac2742eb..442a4323b3 100644
--- a/cpukit/score/src/threadqfirstpriority.c
+++ b/cpukit/score/src/threadqfirstpriority.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-1999.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
diff --git a/cpukit/score/src/threadqflush.c b/cpukit/score/src/threadqflush.c
index ecb9b0df20..f609a0fc60 100644
--- a/cpukit/score/src/threadqflush.c
+++ b/cpukit/score/src/threadqflush.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-1999.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
diff --git a/cpukit/score/src/threadqrequeue.c b/cpukit/score/src/threadqrequeue.c
index a536eecdcf..4c50565b86 100644
--- a/cpukit/score/src/threadqrequeue.c
+++ b/cpukit/score/src/threadqrequeue.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-2006.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be
@@ -46,28 +46,29 @@ void _Thread_queue_Requeue(
   Thread_Control       *the_thread
 )
 {
-  /* just in case the thread really wasn't blocked here */
-  if ( !the_thread_queue ) {
+  /*
+   * Just in case the thread really wasn't blocked on a thread queue
+   * when we get here.
+   */
+  if ( !the_thread_queue )
     return;
-  }
 
-  switch ( the_thread_queue->discipline ) {
-    case THREAD_QUEUE_DISCIPLINE_FIFO:
-      /* queueing by FIFO -- nothing to do */
-      break;
-    case THREAD_QUEUE_DISCIPLINE_PRIORITY: {
-      Thread_queue_Control *tq = the_thread_queue;
-      ISR_Level             level;
+  /*
+   * If queueing by FIFO, there is nothing to do. This only applies to
+   * priority blocking discipline.
+   */
+  if ( the_thread_queue->discipline == THREAD_QUEUE_DISCIPLINE_PRIORITY ) {
+    Thread_queue_Control *tq = the_thread_queue;
+    ISR_Level             level;
+    ISR_Level             level_ignored;
 
-      _ISR_Disable( level );
-      if ( _States_Is_waiting_on_thread_queue( the_thread->current_state ) ) {
-        _Thread_queue_Enter_critical_section( tq );
-        _Thread_queue_Extract_priority_helper( tq, the_thread, TRUE );
-        _Thread_queue_Enqueue_priority( tq, the_thread );
-      }
-      _ISR_Enable( level );
-      break;
+    _ISR_Disable( level );
+    if ( _States_Is_waiting_on_thread_queue( the_thread->current_state ) ) {
+      _Thread_queue_Enter_critical_section( tq );
+      _Thread_queue_Extract_priority_helper( tq, the_thread, TRUE );
+      (void) _Thread_queue_Enqueue_priority( tq, the_thread, &level_ignored );
     }
+    _ISR_Enable( level );
   }
 }
 
diff --git a/cpukit/score/src/threadqtimeout.c b/cpukit/score/src/threadqtimeout.c
index ae11f0b40f..7b0fcd5061 100644
--- a/cpukit/score/src/threadqtimeout.c
+++ b/cpukit/score/src/threadqtimeout.c
@@ -2,7 +2,7 @@
  *  Thread Queue Handler
  *
  *
- *  COPYRIGHT (c) 1989-2007.
+ *  COPYRIGHT (c) 1989-2008.
  *  On-Line Applications Research Corporation (OAR).
  *
  *  The license and distribution terms for this file may be