[v4,1/3] eal: add rte control thread create API

diff --git a/lib/eal/common/eal_common_thread.c b/lib/eal/common/eal_common_thread.c
index c5d8b43..872ad20 100644
--- a/lib/eal/common/eal_common_thread.c
+++ b/lib/eal/common/eal_common_thread.c
@@ -234,7 +234,10 @@  enum __rte_ctrl_thread_status {
 };
 
 struct rte_thread_ctrl_params {
-	void *(*start_routine)(void *);
+	union {
+		void *(*ctrl_start_routine)(void *arg);
+		rte_thread_func control_start_routine;
+	} u;
 	void *arg;
 	int ret;
 	/* Control thread status.
@@ -243,14 +246,12 @@  struct rte_thread_ctrl_params {
 	enum __rte_ctrl_thread_status ctrl_thread_status;
 };
 
-static void *ctrl_thread_init(void *arg)
+static int ctrl_thread_init(void *arg)
 {
 	struct internal_config *internal_conf =
 		eal_get_internal_configuration();
 	rte_cpuset_t *cpuset = &internal_conf->ctrl_cpuset;
 	struct rte_thread_ctrl_params *params = arg;
-	void *(*start_routine)(void *) = params->start_routine;
-	void *routine_arg = params->arg;
 
 	__rte_thread_init(rte_lcore_id(), cpuset);
 	params->ret = pthread_setaffinity_np(pthread_self(), sizeof(*cpuset),
@@ -258,13 +259,35 @@  static void *ctrl_thread_init(void *arg)
 	if (params->ret != 0) {
 		__atomic_store_n(&params->ctrl_thread_status,
 			CTRL_THREAD_ERROR, __ATOMIC_RELEASE);
-		return NULL;
+		return params->ret;
 	}
 
 	__atomic_store_n(&params->ctrl_thread_status,
 		CTRL_THREAD_RUNNING, __ATOMIC_RELEASE);
 
-	return start_routine(routine_arg);
+	return 0;
+}
+
+static void *ctrl_thread_start(void *arg)
+{
+	struct rte_thread_ctrl_params *params = arg;
+	void *(*start_routine)(void *) = params->u.ctrl_start_routine;
+
+	if (ctrl_thread_init(arg) != 0)
+		return NULL;
+
+	return start_routine(params->arg);
+}
+
+static uint32_t control_thread_start(void *arg)
+{
+	struct rte_thread_ctrl_params *params = arg;
+	rte_thread_func start_routine = params->u.control_start_routine;
+
+	if (ctrl_thread_init(arg) != 0)
+		return params->ret;
+
+	return start_routine(params->arg);
 }
 
 int
@@ -280,12 +303,12 @@  static void *ctrl_thread_init(void *arg)
 	if (!params)
 		return -ENOMEM;
 
-	params->start_routine = start_routine;
+	params->u.ctrl_start_routine = start_routine;
 	params->arg = arg;
 	params->ret = 0;
 	params->ctrl_thread_status = CTRL_THREAD_LAUNCHING;
 
-	ret = pthread_create(thread, attr, ctrl_thread_init, (void *)params);
+	ret = pthread_create(thread, attr, ctrl_thread_start, (void *)params);
 	if (ret != 0) {
 		free(params);
 		return -ret;
@@ -322,6 +345,56 @@  static void *ctrl_thread_init(void *arg)
 }
 
 int
+rte_control_thread_create(rte_thread_t *thread, const char *name,
+	const rte_thread_attr_t *attr,
+	rte_thread_func start_routine, void *arg)
+{
+	struct rte_thread_ctrl_params *params;
+	enum __rte_ctrl_thread_status ctrl_thread_status;
+	int ret;
+
+	params = malloc(sizeof(*params));
+	if (params == NULL)
+		return -ENOMEM;
+
+	params->u.control_start_routine = start_routine;
+	params->arg = arg;
+	params->ret = 0;
+	params->ctrl_thread_status = CTRL_THREAD_LAUNCHING;
+
+	ret = rte_thread_create(thread, attr, control_thread_start, params);
+	if (ret != 0) {
+		free(params);
+		return -ret;
+	}
+
+	if (name != NULL) {
+		ret = rte_thread_setname((pthread_t)thread->opaque_id, name);
+		if (ret < 0)
+			RTE_LOG(DEBUG, EAL,
+				"Cannot set name for ctrl thread\n");
+	}
+
+	/* Wait for the control thread to initialize successfully */
+	while ((ctrl_thread_status =
+			__atomic_load_n(&params->ctrl_thread_status,
+			__ATOMIC_ACQUIRE)) == CTRL_THREAD_LAUNCHING) {
+		rte_delay_us_sleep(1);
+	}
+
+	/* Check if the control thread encountered an error */
+	if (ctrl_thread_status == CTRL_THREAD_ERROR) {
+		/* ctrl thread is exiting */
+		rte_thread_join(*thread, NULL);
+	}
+
+	ret = params->ret;
+	free(params);
+
+	return ret;
+}
+
+int
 rte_thread_register(void)
 {
 	unsigned int lcore_id;
diff --git a/lib/eal/include/rte_thread.h b/lib/eal/include/rte_thread.h
index b9edf70..97c27a9 100644
--- a/lib/eal/include/rte_thread.h
+++ b/lib/eal/include/rte_thread.h
@@ -95,6 +95,36 @@  int rte_thread_create(rte_thread_t *thread_id,
 		rte_thread_func thread_func, void *arg);
 
 /**
+ * Create a control thread.
+ *
+ * Creates a control thread with the given name and attributes. The
+ * affinity of the new thread is based on the CPU affinity retrieved
+ * at the time rte_eal_init() was called, the EAL threads are then
+ * excluded. If setting the name of the thread fails, the error is
+ * ignored and a debug message is logged.
+ *
+ * @param thread
+ *   Filled with the thread id of the new created thread.
+ * @param name
+ *   The name of the control thread
+ *   (max RTE_MAX_THREAD_NAME_LEN characters including '\0').
+ * @param thread_attr
+ *   Attributes for the new thread.
+ * @param thread_func
+ *   Function to be executed by the new thread.
+ * @param arg
+ *   Argument passed to start_routine.
+ * @return
+ *   On success, returns 0; on error, it returns a negative value
+ *   corresponding to the error number.
+ */
+__rte_experimental
+int
+rte_control_thread_create(rte_thread_t *thread, const char *name,
+		const rte_thread_attr_t *thread_attr,
+		rte_thread_func thread_func, void *arg);
+
+/**
  * @warning
  * @b EXPERIMENTAL: this API may change without prior notice.
  *
diff --git a/lib/eal/version.map b/lib/eal/version.map
index 7ad12a7..8f9eeb9 100644
--- a/lib/eal/version.map
+++ b/lib/eal/version.map
@@ -440,6 +440,9 @@  EXPERIMENTAL {
 	rte_thread_detach;
 	rte_thread_equal;
 	rte_thread_join;
+
+	# added in 23.03
+	rte_control_thread_create;
 };
 
 INTERNAL {