1 files changed, 62 insertions, 11 deletions

diff --git a/cpukit/score/src/futex.c b/cpukit/score/src/futex.c
index b65a843704..e158b61238 100644
--- a/cpukit/score/src/futex.c
+++ b/cpukit/score/src/futex.c
@@ -1,23 +1,49 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
 /**
  * @file
  *
- * @ingroup RTEMSScore
+ * @ingroup RTEMSScoreFutex
  *
  * @brief This source file contains the implementation of
  *   _Futex_Wait() and _Futex_Wake().
  */
+
 /*
- * Copyright (c) 2015, 2016 embedded brains GmbH.  All rights reserved.
+ * Copyright (C) 2015, 2016 embedded brains GmbH & Co. KG
+ *
+ * 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.
+ */
+
+/**
+ * @defgroup RTEMSScoreFutex Futex Handler
+ *
+ * @ingroup RTEMSScore
+ *
+ * @brief This group contains the Futex Handler implementation.
  *
- *  embedded brains GmbH
- *  Dornierstr. 4
- *  82178 Puchheim
- *  Germany
- *  <rtems@embedded-brains.de>
+ * The behaviour of the futex operations is defined by Linux, see also:
  *
- * 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.
+ * https://man7.org/linux/man-pages/man2/futex.2.html
  */
 
 #ifdef HAVE_CONFIG_H
@@ -84,6 +110,22 @@ static void _Futex_Queue_release(
   _ISR_Local_enable( level );
 }
 
+/**
+ * @brief Performs the ``FUTEX_WAIT`` operation.
+ *
+ * @param[in, out] _futex is the futex object.
+ *
+ * @param[in] uaddr is the address to the futex state.
+ *
+ * @param val is the expected futex state value.
+ *
+ * @retval 0 Returns zero if the futex state is equal to the expected value.
+ *   In this case the calling thread is enqueued on the thread queue of the
+ *   futex object.
+ *
+ * @retval EAGAIN Returns EAGAIN if the futex state is not equal to the
+ *   expected value.
+ */
 int _Futex_Wait( struct _Futex_Control *_futex, int *uaddr, int val )
 {
   Futex_Control        *futex;
@@ -113,7 +155,7 @@ int _Futex_Wait( struct _Futex_Control *_futex, int *uaddr, int val )
     eno = 0;
   } else {
     _Futex_Queue_release( futex, level, &queue_context );
-    eno = EWOULDBLOCK;
+    eno = EAGAIN;
   }
 
   return eno;
@@ -143,6 +185,15 @@ static Thread_Control *_Futex_Flush_filter(
   return the_thread;
 }
 
+/**
+ * @brief Performs the ``FUTEX_WAKE`` operation.
+ *
+ * @param[in, out] _futex is the futex object.
+ *
+ * @param count is the maximum count of threads to wake up.
+ *
+ * @return Returns the count of woken up threads.
+ */
 int _Futex_Wake( struct _Futex_Control *_futex, int count )
 {
   Futex_Control *futex;