score: Avoid some deadlocks in _Once()

Recursive usage of the same pthread_once_t results now in a deadlock.
Previously, an error of EINVAL was returned.  This usage scenario is
invalid according to the POSIX pthread_once() specification.

Close #3334.

1 files changed, 74 insertions, 43 deletions

diff --git a/cpukit/score/src/once.c b/cpukit/score/src/once.c
index 5237c11878..2b2cc0e89b 100644
--- a/cpukit/score/src/once.c
+++ b/cpukit/score/src/once.c
@@ -1,68 +1,99 @@
 /*
- *  COPYRIGHT (c) 1989-1999.
- *  On-Line Applications Research Corporation (OAR).
+ * SPDX-License-Identifier: BSD-2-Clause
  *
- *  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.
+ * Copyright (C) 2019 embedded brains GmbH
+ * Copyright (C) 2019 Sebastian Huber
+ *
+ * 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"
+#include "config.h"
 #endif
 
 #include <rtems/score/onceimpl.h>
-#include <rtems/score/apimutex.h>
+#include <rtems/score/threadimpl.h>
+#include <rtems/thread.h>
+
+#define ONCE_STATE_INIT 0
 
-#include <errno.h>
+#define ONCE_STATE_RUNNING 1
 
-#define ONCE_STATE_NOT_RUN  0
-#define ONCE_STATE_RUNNING  1
 #define ONCE_STATE_COMPLETE 2
 
+typedef struct {
+  rtems_mutex              Mutex;
+  rtems_condition_variable State;
+} Once_Control;
+
+static Once_Control _Once_Information = {
+  .Mutex = RTEMS_MUTEX_INITIALIZER( "_Once" ),
+  .State = RTEMS_CONDITION_VARIABLE_INITIALIZER( "_Once" )
+};
+
 int _Once( unsigned char *once_state, void ( *init_routine )( void ) )
 {
-  int eno = 0;
-
-  if ( *once_state != ONCE_STATE_COMPLETE ) {
-    _Once_Lock();
-
-    /*
-     * Getting to here means the once_control is locked so we have:
-     *  1. The init has not run and the state is ONCE_STATE_NOT_RUN.
-     *  2. The init has finished and the state is ONCE_STATE_COMPLETE (already
-     *     caught by the previous if).
-     *  3. The init is being run by this thread and the state
-     *     ONCE_STATE_RUNNING so we are nesting. This is an error.
-     */
-
-    switch ( *once_state ) {
-      case ONCE_STATE_NOT_RUN:
-        *once_state = ONCE_STATE_RUNNING;
-        ( *init_routine )();
-        *once_state = ONCE_STATE_COMPLETE;
-        break;
-      case ONCE_STATE_RUNNING:
-        eno = EINVAL;
-        break;
-      default:
-        break;
+  _Atomic_Fence( ATOMIC_ORDER_ACQUIRE );
+
+  if ( RTEMS_PREDICT_FALSE( *once_state != ONCE_STATE_COMPLETE ) ) {
+    Thread_Life_state thread_life_state;
+
+    thread_life_state = _Once_Lock();
+
+    if ( *once_state == ONCE_STATE_INIT ) {
+      *once_state = ONCE_STATE_RUNNING;
+      _Once_Unlock( THREAD_LIFE_PROTECTED );
+      ( *init_routine )();
+      _Once_Lock();
+      _Atomic_Fence( ATOMIC_ORDER_RELEASE );
+      *once_state = ONCE_STATE_COMPLETE;
+      rtems_condition_variable_broadcast( &_Once_Information.State );
+    } else {
+      while ( *once_state != ONCE_STATE_COMPLETE ) {
+        rtems_condition_variable_wait(
+          &_Once_Information.State,
+          &_Once_Information.Mutex
+        );
+      }
     }
 
-    _Once_Unlock();
+    _Once_Unlock( thread_life_state );
   }
 
-  return eno;
+  return 0;
 }
 
-static API_Mutex_Control _Once_Mutex = API_MUTEX_INITIALIZER( "_Once" );
-
-void _Once_Lock( void )
+Thread_Life_state _Once_Lock( void )
 {
-  _API_Mutex_Lock( &_Once_Mutex );
+  Thread_Life_state thread_life_state;
+
+  thread_life_state = _Thread_Set_life_protection( THREAD_LIFE_PROTECTED );
+  rtems_mutex_lock( &_Once_Information.Mutex );
+
+  return thread_life_state;
 }
 
-void _Once_Unlock( void )
+void _Once_Unlock( Thread_Life_state thread_life_state )
 {
-  _API_Mutex_Unlock( &_Once_Mutex );
+  rtems_mutex_unlock( &_Once_Information.Mutex );
+  _Thread_Set_life_protection( thread_life_state );
 }