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.

1 files changed, 71 insertions, 0 deletions

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;
+}