portability: cmsis: Remove max limit on new statically created threads

Clarify thread Kconfigs to denote the maximum number of dynamically
allocated control blocks and stacks for threads. Allow application to
create any number of threads with statically allocated control block
and stack.

Signed-off-by: Utsav Munendra <utsavm@meta.com>

subsys/portability/cmsis_rtos_v2/Kconfig

@@ -16,23 +16,20 @@ config CMSIS_RTOS_V2
 
 if CMSIS_RTOS_V2
 config CMSIS_V2_THREAD_MAX_COUNT
-	int "Maximum thread count in CMSIS RTOS V2 application"
+	int "Maximum thread count in CMSIS RTOS V2 application with dynamic control blocks"
 	default 15
 	range 0 $(UINT8_MAX)
 	help
-	  Mention max number of threads in CMSIS RTOS V2 compliant application.
+	  Max number of threads in CMSIS RTOS V2 application that can be created with
-	  There's a limitation on the number of threads due to memory
+		dynamically allocated control block.
-	  related constraints.
 
 config CMSIS_V2_THREAD_DYNAMIC_MAX_COUNT
-	int "Maximum dynamic thread count in CMSIS RTOS V2 application"
+	int "Maximum thread count in CMSIS RTOS V2 application with dynamic stack"
 	default 0
 	range 0 $(UINT8_MAX)
 	help
-	  Mention max number of dynamic threads in CMSIS RTOS V2 compliant
+	  Max number of threads in CMSIS RTOS V2 application that can be created with
-	  application. There's a limitation on the number of threads due to memory
+		dynamically allocated stack.
-	  related constraints. Dynamic threads are a subset of all other CMSIS
-	  threads i.e. they also count towards that maximum too.
 
 config CMSIS_V2_THREAD_MAX_STACK_SIZE
 	int "Max stack size threads can be allocated in CMSIS RTOS V2 application"

subsys/portability/cmsis_rtos_v2/thread.c

@@ -26,10 +26,11 @@ static const osThreadAttr_t init_thread_attrs = {
 };
 
 static sys_dlist_t thread_list;
-static atomic_t thread_num;
 
 static atomic_t num_dynamic_cb;
+#if CONFIG_CMSIS_V2_THREAD_MAX_COUNT != 0
 static struct cmsis_rtos_thread_cb cmsis_rtos_thread_cb_pool[CONFIG_CMSIS_V2_THREAD_MAX_COUNT];
+#endif
 
 static atomic_t num_dynamic_stack;
 #if CONFIG_CMSIS_V2_THREAD_DYNAMIC_MAX_COUNT != 0
@@ -106,17 +107,11 @@ osThreadId_t osThreadNew(osThreadFunc_t threadfunc, void *arg, const osThreadAtt
 	static uint32_t one_time;
 	void *stack;
 	size_t stack_size;
-	uint32_t this_thread_num;
-	uint32_t this_dynamic_cb;
 
 	if (k_is_in_isr()) {
 		return NULL;
 	}
 
-	if (thread_num >= CONFIG_CMSIS_V2_THREAD_MAX_COUNT) {
-		return NULL;
-	}
-
 	if (attr == NULL) {
 		attr = &init_thread_attrs;
 	}
@@ -139,9 +134,6 @@ osThreadId_t osThreadNew(osThreadFunc_t threadfunc, void *arg, const osThreadAtt
 	BUILD_ASSERT(osPriorityISR <= CONFIG_NUM_PREEMPT_PRIORITIES,
 		     "Configure NUM_PREEMPT_PRIORITIES to at least osPriorityISR");
 
-	BUILD_ASSERT(CONFIG_CMSIS_V2_THREAD_DYNAMIC_MAX_COUNT <= CONFIG_CMSIS_V2_THREAD_MAX_COUNT,
-		     "Number of dynamic threads cannot exceed max number of threads.");
-
 	BUILD_ASSERT(CONFIG_CMSIS_V2_THREAD_DYNAMIC_STACK_SIZE <=
 			     CONFIG_CMSIS_V2_THREAD_MAX_STACK_SIZE,
 		     "Default dynamic thread stack size cannot exceed max stack size");
@@ -150,18 +142,18 @@ osThreadId_t osThreadNew(osThreadFunc_t threadfunc, void *arg, const osThreadAtt
 
 	__ASSERT((cv2_prio >= osPriorityIdle) && (cv2_prio <= osPriorityISR), "invalid priority\n");
 
-	if (attr->stack_mem != NULL) {
+	if (attr->stack_mem != NULL && attr->stack_size == 0) {
-		if (attr->stack_size == 0) {
+		return NULL;
-			return NULL;
-		}
 	}
 
-	this_thread_num = atomic_inc(&thread_num);
+#if CONFIG_CMSIS_V2_THREAD_MAX_COUNT != 0
-
 	if (attr->cb_mem == NULL) {
+		uint32_t this_dynamic_cb;
 		this_dynamic_cb = atomic_inc(&num_dynamic_cb);
 		tid = &cmsis_rtos_thread_cb_pool[this_dynamic_cb];
-	} else {
+	} else
+#endif
+	{
 		tid = (struct cmsis_rtos_thread_cb *)attr->cb_mem;
 	}
 

tests/subsys/portability/cmsis_rtos_v2/src/thread_apis.c

@@ -417,4 +417,34 @@ ZTEST(cmsis_thread_apis, test_thread_apis_join_after_exit)
 	status = osThreadJoin(id);
 	zassert_equal(status, osOK, "osThreadJoin failed with status=%d!", status);
 }
+
+static K_THREAD_STACK_DEFINE(test_stack9, STACKSZ);
+static struct cmsis_rtos_thread_cb test_cb9;
+static const osThreadAttr_t os_thread9_attr = {
+	.name = "Thread9",
+	.attr_bits = osThreadJoinable,
+	.cb_mem = &test_cb9,
+	.cb_size = sizeof(test_cb9),
+	.stack_mem = &test_stack9,
+	.stack_size = STACKSZ,
+	.priority = osPriorityNormal,
+};
+static void thread9(void *argument)
+{
+	osThreadExit();
+}
+ZTEST(cmsis_thread_apis, test_thread_apis_multiple_new_static)
+{
+	osThreadId_t id;
+	osStatus_t status;
+
+	for (int i = 0; i < 100; i++) {
+		id = osThreadNew(thread9, NULL, &os_thread9_attr);
+		zassert_not_null(id,
+				 "Failed to create thread with osThreadNew using static cb/stack");
+
+		status = osThreadJoin(id);
+		zassert_equal(status, osOK, "osThreadJoin failed with status=%d!", status);
+	}
+}
 ZTEST_SUITE(cmsis_thread_apis, NULL, NULL, NULL, NULL, NULL);