lib: cmsis_rtos_v2: Join and detach support

Implements osThreadJoin and osThreadDetach.

This implementation uses a semaphore to signal when a thread is
exiting so any join operations are signalled to continue. It supports
multiple join operations on a single thread, and ensures joins are
aborted if a thread is detached.

Signed-off-by: Carlos Stuart <carlosstuart1970@gmail.com>

lib/cmsis_rtos_v2/thread.c

@@ -52,9 +52,13 @@ static inline u32_t cmsis_to_zephyr_priority(u32_t c_prio)
 
 static void zephyr_thread_wrapper(void *arg1, void *arg2, void *arg3)
 {
+	struct cv2_thread *tid = arg2;
 	void * (*fun_ptr)(void *) = arg3;
 
 	fun_ptr(arg1);
+
+	tid->has_joined = TRUE;
+	k_sem_give(&tid->join_guard);
 }
 
 void *is_cmsis_rtos_v2_thread(void *thread_id)
@@ -157,7 +161,7 @@ osThreadId_t osThreadNew(osThreadFunc_t threadfunc, void *arg,
 	this_thread_num = atomic_inc((atomic_t *)&thread_num);
 
 	tid = &cv2_thread_pool[this_thread_num];
-	tid->state = attr->attr_bits;
+	tid->attr_bits = attr->attr_bits;
 
 	if (attr->stack_mem == NULL) {
 		__ASSERT(CONFIG_CMSIS_V2_THREAD_DYNAMIC_STACK_SIZE > 0,
@@ -184,13 +188,15 @@ osThreadId_t osThreadNew(osThreadFunc_t threadfunc, void *arg,
 
 	sys_dlist_append(&thread_list, &tid->node);
 
+	k_sem_init(&tid->join_guard, 0, 1);
+	tid->has_joined = FALSE;
+
 	(void)k_thread_create(&tid->z_thread,
 			      stack, stack_size,
 			      (k_thread_entry_t)zephyr_thread_wrapper,
-			      (void *)arg, NULL, threadfunc,
+			      (void *)arg, tid, threadfunc,
 			      prio, 0, K_NO_WAIT);
 
-
 	if (attr->name == NULL) {
 		strncpy(tid->name, init_thread_attrs.name,
 			sizeof(tid->name) - 1);
@@ -417,6 +423,77 @@ osStatus_t osThreadResume(osThreadId_t thread_id)
 	return osOK;
 }
 
+/**
+ * @brief Detach a thread (thread storage can be reclaimed when thread
+ *        terminates).
+ */
+osStatus_t osThreadDetach(osThreadId_t thread_id)
+{
+	struct cv2_thread *tid = (struct cv2_thread *)thread_id;
+
+	if ((tid == NULL) || (is_cmsis_rtos_v2_thread(tid) == NULL)) {
+		return osErrorParameter;
+	}
+
+	if (k_is_in_isr()) {
+		return osErrorISR;
+	}
+
+	if (_is_thread_cmsis_inactive(&tid->z_thread)) {
+		return osErrorResource;
+	}
+
+	__ASSERT(tid->attr_bits != osThreadDetached,
+		 "Thread already detached, behaviour undefined.");
+
+	tid->attr_bits = osThreadDetached;
+
+	k_sem_give(&tid->join_guard);
+
+	return osOK;
+}
+
+/**
+ * @brief Wait for specified thread to terminate.
+ */
+osStatus_t osThreadJoin(osThreadId_t thread_id)
+{
+	struct cv2_thread *tid = (struct cv2_thread *)thread_id;
+	osStatus_t status = osError;
+
+	if ((tid == NULL) || (is_cmsis_rtos_v2_thread(tid) == NULL)) {
+		return osErrorParameter;
+	}
+
+	if (k_is_in_isr()) {
+		return osErrorISR;
+	}
+
+	if (_is_thread_cmsis_inactive(&tid->z_thread)) {
+		return osErrorResource;
+	}
+
+	if (tid->attr_bits != osThreadJoinable) {
+		return osErrorResource;
+	}
+
+	if (!tid->has_joined) {
+		if (k_sem_take(&tid->join_guard, K_FOREVER) != 0) {
+			__ASSERT(0, "Failed to take from join guard.");
+		}
+
+		k_sem_give(&tid->join_guard);
+	}
+
+	if (tid->has_joined && (tid->attr_bits == osThreadJoinable)) {
+		status = osOK;
+	} else {
+		status = osErrorResource;
+	}
+
+	return status;
+}
+
 /**
  * @brief Terminate execution of current running thread.
  */
@@ -427,6 +504,8 @@ __NO_RETURN void osThreadExit(void)
 	__ASSERT(!k_is_in_isr(), "");
 	tid = osThreadGetId();
 
+	k_sem_give(&tid->join_guard);
+
 	k_thread_abort((k_tid_t)&tid->z_thread);
 
 	CODE_UNREACHABLE;
@@ -451,6 +530,8 @@ osStatus_t osThreadTerminate(osThreadId_t thread_id)
 		return osErrorResource;
 	}
 
+	k_sem_give(&tid->join_guard);
+
 	k_thread_abort((k_tid_t)&tid->z_thread);
 	return osOK;
 }

lib/cmsis_rtos_v2/wrapper.h

@@ -20,7 +20,9 @@ struct cv2_thread {
 	struct k_poll_event poll_event;
 	u32_t signal_results;
 	char name[16];
-	u32_t state;
+	u32_t attr_bits;
+	struct k_sem join_guard;
+	char has_joined;
 };
 
 struct cv2_timer {