From 11ef1d10b8d1cce9fa6ba82e3c241876cb7f8fbc Mon Sep 17 00:00:00 2001
From: Russ Butler <russ.butler@arm.com>
Date: Wed, 1 Mar 2017 14:37:55 -0600
Subject: [PATCH 1/3] rtos: Return an error when a Thread is re-used

Calling Thread::start multiple times leads to undefined behavior since
the Thread class was not designed to handle being restarted.  Return an
error code if Thread::start is called a second time to prevent this
behavior.
---
 rtos/Thread.cpp | 5 ++++-
 rtos/Thread.h   | 4 +++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/rtos/Thread.cpp b/rtos/Thread.cpp
index 61bfe964c6..c168afde2f 100644
--- a/rtos/Thread.cpp
+++ b/rtos/Thread.cpp
@@ -44,6 +44,7 @@ namespace rtos {
 void Thread::constructor(osPriority priority,
         uint32_t stack_size, unsigned char *stack_pointer) {
     _tid = 0;
+    _finished = false;
     _dynamic_stack = (stack_pointer == NULL);
 
 #if defined(__MBED_CMSIS_RTOS_CA9) || defined(__MBED_CMSIS_RTOS_CM)
@@ -74,7 +75,7 @@ void Thread::constructor(Callback<void()> task,
 osStatus Thread::start(Callback<void()> task) {
     _mutex.lock();
 
-    if (_tid != 0) {
+    if ((_tid != 0) || _finished) {
         _mutex.unlock();
         return osErrorParameter;
     }
@@ -117,6 +118,7 @@ osStatus Thread::terminate() {
     osThreadId local_id = _tid;
     _join_sem.release();
     _tid = (osThreadId)NULL;
+    _finished = true;
 
     ret = osThreadTerminate(local_id);
 
@@ -367,6 +369,7 @@ void Thread::_thunk(const void * thread_ptr)
     t->_task();
     t->_mutex.lock();
     t->_tid = (osThreadId)NULL;
+    t->_finished = true;
     t->_join_sem.release();
     // rtos will release the mutex automatically
 }
diff --git a/rtos/Thread.h b/rtos/Thread.h
index 6c480d74b7..1df34c3712 100644
--- a/rtos/Thread.h
+++ b/rtos/Thread.h
@@ -197,6 +197,7 @@ public:
     /** Starts a thread executing the specified function.
       @param   task           function to be executed by this thread.
       @return  status code that indicates the execution status of the function.
+      @note a thread can only be started once
     */
     osStatus start(mbed::Callback<void()> task);
 
@@ -344,9 +345,10 @@ private:
     mbed::Callback<void()> _task;
     osThreadId _tid;
     osThreadDef_t _thread_def;
-    bool _dynamic_stack;
     Semaphore _join_sem;
     Mutex _mutex;
+    bool _dynamic_stack;
+    bool _finished;
 };
 
 }

From 05403d4231a5665eac69f17bf9c0ce87c323239e Mon Sep 17 00:00:00 2001
From: Russ Butler <russ.butler@arm.com>
Date: Fri, 3 Mar 2017 11:31:50 -0600
Subject: [PATCH 2/3] rtos: Add Inactive return to thread get state

If a thread hasn't been started return Inactive as the status when
Thread::get_state() is called.
---
 rtos/Thread.cpp | 6 +++++-
 rtos/Thread.h   | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/rtos/Thread.cpp b/rtos/Thread.cpp
index c168afde2f..9969e09670 100644
--- a/rtos/Thread.cpp
+++ b/rtos/Thread.cpp
@@ -179,11 +179,15 @@ int32_t Thread::signal_clr(int32_t signals) {
 Thread::State Thread::get_state() {
 #if !defined(__MBED_CMSIS_RTOS_CA9) && !defined(__MBED_CMSIS_RTOS_CM)
 #ifdef CMSIS_OS_RTX
-    State status = Deleted;
+    State status;
     _mutex.lock();
 
     if (_tid != NULL) {
         status = (State)_thread_def.tcb.state;
+    } else if (_finished) {
+        status = Deleted;
+    } else {
+        status = Inactive;
     }
 
     _mutex.unlock();
diff --git a/rtos/Thread.h b/rtos/Thread.h
index 1df34c3712..edad0840e9 100644
--- a/rtos/Thread.h
+++ b/rtos/Thread.h
@@ -252,7 +252,7 @@ public:
 
     /** State of the Thread */
     enum State {
-        Inactive,           /**< Not created or terminated */
+        Inactive,           /**< Not created */
         Ready,              /**< Ready to run */
         Running,            /**< Running */
         WaitingDelay,       /**< Waiting for a delay to occur */

From ab4da40e81c8d08deba5ac10e37a888afcbb05f1 Mon Sep 17 00:00:00 2001
From: Russ Butler <russ.butler@arm.com>
Date: Mon, 6 Mar 2017 11:54:17 -0600
Subject: [PATCH 3/3] rtos: Prevent Thread class from being copied

Make the copy constructor and assignment operator private to prevent
them from being used.
---
 rtos/Thread.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/rtos/Thread.h b/rtos/Thread.h
index edad0840e9..d2bae4fb01 100644
--- a/rtos/Thread.h
+++ b/rtos/Thread.h
@@ -331,6 +331,10 @@ public:
     virtual ~Thread();
 
 private:
+    /* disallow copy constructor and assignment operators */
+    Thread(const Thread&);
+    Thread& operator=(const Thread&);
+
     // Required to share definitions without
     // delegated constructors
     void constructor(osPriority priority=osPriorityNormal,