Fix thread self termination

TESTS/mbedmicro-rtos-mbed/threads/main.cpp

@@ -59,6 +59,12 @@ void increment_with_murder(counter_t* counter) {
     (*counter)++;
 }
 
+void self_terminate(Thread *self) {
+    self->terminate();
+    // Code should not get here
+    TEST_ASSERT(0);
+}
+
 // Tests that spawn tasks in different configurations
 template <void (*F)(counter_t *)>
 void test_single_thread() {
@@ -97,6 +103,13 @@ void test_serial_threads() {
     TEST_ASSERT_EQUAL(counter, N);
 }
 
+void test_self_terminate() {
+    Thread *thread = new Thread(osPriorityNormal, STACK_SIZE);
+    thread->start(thread, self_terminate);
+    thread->join();
+    delete thread;
+}
+
 utest::v1::status_t test_setup(const size_t number_of_cases) {
     GREENTEA_SETUP(40, "default_auto");
     return verbose_test_setup_handler(number_of_cases);
@@ -123,6 +136,8 @@ Case cases[] = {
     Case("Testing single thread with murder", test_single_thread<increment_with_murder>),
     Case("Testing parallel threads with murder", test_parallel_threads<3, increment_with_murder>),
     Case("Testing serial threads with murder", test_serial_threads<10, increment_with_murder>),
+
+    Case("Testing thread self terminate", test_self_terminate),
 };
 
 Specification specification(test_setup, cases);

rtos/rtos/Thread.cpp

@@ -101,11 +101,14 @@ osStatus Thread::terminate() {
     osStatus ret;
     _mutex.lock();
 
-    ret = osThreadTerminate(_tid);
+    // Set the Thread's tid to NULL and
+    // release the semaphore before terminating
+    // since this thread could be terminating itself
+    osThreadId local_id = _tid;
+    _join_sem.release();
     _tid = (osThreadId)NULL;
 
-    // Wake threads joining the terminated thread
-    _join_sem.release();
+    ret = osThreadTerminate(local_id);
 
     _mutex.unlock();
     return ret;
@@ -116,6 +119,14 @@ osStatus Thread::join() {
     if (ret < 0) {
         return osErrorOS;
     }
+
+    // The semaphore has been released so this thread is being
+    // terminated or has been terminated. Once the mutex has
+    // been locked it is ensured that the thread is deleted.
+    _mutex.lock();
+    MBED_ASSERT(NULL == _tid);
+    _mutex.unlock();
+
     // Release sem so any other threads joining this thread wake up
     _join_sem.release();
     return osOK;