rtems: Fix rate monotonic statistics

The rate monotonic period statistics were affected by
rtems_cpu_usage_reset().  The logic to detect and work around a CPU
usage reset was broken.

The Thread_Contol::cpu_time_used is changed to contain the processor
time used throughout the entire lifetime of the thread.  The new member
Thread_Contol::cpu_time_used_at_last_reset is added to contain the
processor time used at the time of the last reset through
rtems_cpu_usage_reset().  This decouples the resets of the CPU usage and
the rate monotonic period statistics.

Update #4528.

2 files changed, 94 insertions, 9 deletions

diff --git a/cpukit/score/src/threadgetcputimeused.c b/cpukit/score/src/threadgetcputimeused.c
index 7406da0bf3..f23f606411 100644
--- a/cpukit/score/src/threadgetcputimeused.c
+++ b/cpukit/score/src/threadgetcputimeused.c
@@ -4,7 +4,7 @@
  * @ingroup RTEMSScoreThread
  *
  * @brief This source file contains the implementation of
- *   _Thread_Get_CPU_time_used().
+ *   _Thread_Get_CPU_time_used() and _Thread_Get_CPU_time_used_locked().
  */
 
 /*
@@ -37,25 +37,39 @@ static bool _Thread_Is_scheduled( const Thread_Control *the_thread )
 #endif
 }
 
-void _Thread_Get_CPU_time_used(
-  Thread_Control    *the_thread,
-  Timestamp_Control *cpu_time_used
+Timestamp_Control _Thread_Get_CPU_time_used_locked(
+  Thread_Control *the_thread
 )
 {
+  _Assert( _Thread_State_is_owner( the_thread ) );
+  _Assert(
+    _ISR_lock_Is_owner(
+      &_Scheduler_Get_context( _Thread_Scheduler_get_home( the_thread ) )->Lock
+    )
+  );
+
+  if ( _Thread_Is_scheduled( the_thread ) ) {
+    _Thread_Update_CPU_time_used( the_thread, _Thread_Get_CPU( the_thread ) );
+  }
+
+  return the_thread->cpu_time_used;
+}
+
+Timestamp_Control _Thread_Get_CPU_time_used( Thread_Control *the_thread )
+{
   const Scheduler_Control *scheduler;
   ISR_lock_Context         state_lock_context;
   ISR_lock_Context         scheduler_lock_context;
+  Timestamp_Control        cpu_time_used;
 
   _Thread_State_acquire( the_thread, &state_lock_context );
   scheduler = _Thread_Scheduler_get_home( the_thread );
   _Scheduler_Acquire_critical( scheduler, &scheduler_lock_context );
 
-  if ( _Thread_Is_scheduled( the_thread ) ) {
-    _Thread_Update_CPU_time_used( the_thread, _Thread_Get_CPU( the_thread ) );
-  }
-
-  *cpu_time_used = the_thread->cpu_time_used;
+  cpu_time_used = _Thread_Get_CPU_time_used_locked( the_thread );
 
   _Scheduler_Release_critical( scheduler, &scheduler_lock_context );
   _Thread_State_release( the_thread, &state_lock_context );
+
+  return cpu_time_used;
 }
diff --git a/cpukit/score/src/threadgetcputimeusedafterreset.c b/cpukit/score/src/threadgetcputimeusedafterreset.c
new file mode 100644
index 0000000000..1ab4aa16fb
--- /dev/null
+++ b/cpukit/score/src/threadgetcputimeusedafterreset.c
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/**
+ * @file
+ *
+ * @ingroup RTEMSScoreThread
+ *
+ * @brief This source file contains the implementation of
+ *   _Thread_Get_CPU_time_used_after_last_reset().
+ */
+
+/*
+ * Copyright (C) 2021 embedded brains GmbH (http://www.embedded-brains.de)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/score/threadimpl.h>
+#include <rtems/score/schedulerimpl.h>
+
+Timestamp_Control _Thread_Get_CPU_time_used_after_last_reset(
+  Thread_Control *the_thread
+)
+{
+  const Scheduler_Control *scheduler;
+  ISR_lock_Context         state_lock_context;
+  ISR_lock_Context         scheduler_lock_context;
+  Timestamp_Control        cpu_time_used;
+  Timestamp_Control        cpu_time_used_at_last_reset;
+
+  _Thread_State_acquire( the_thread, &state_lock_context );
+  scheduler = _Thread_Scheduler_get_home( the_thread );
+  _Scheduler_Acquire_critical( scheduler, &scheduler_lock_context );
+
+  cpu_time_used = _Thread_Get_CPU_time_used_locked( the_thread );
+  cpu_time_used_at_last_reset = the_thread->cpu_time_used_at_last_reset;
+
+  _Scheduler_Release_critical( scheduler, &scheduler_lock_context );
+  _Thread_State_release( the_thread, &state_lock_context );
+
+  _Timestamp_Subtract(
+    &cpu_time_used_at_last_reset,
+    &cpu_time_used,
+    &cpu_time_used
+  );
+
+  return cpu_time_used;
+}