eal: add multiprocess disable API

The multiprocess feature has been implicitly enabled so far.
Applications might want to explicitly disable like when using the
non-EAL threads registration API.

Signed-off-by: David Marchand <david.marchand@redhat.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

app/test/test_mp_secondary.c

@@ -97,6 +97,13 @@ run_secondary_instances(void)
 			(1 << rte_get_master_lcore()));
 
 	ret |= launch_proc(argv1);
+	printf("### Testing rte_mp_disable() reject:\n");
+	if (rte_mp_disable()) {
+		printf("Error: rte_mp_disable() has been accepted\n");
+		ret |= -1;
+	} else {
+		printf("# Checked rte_mp_disable() is refused\n");
+	}
 	ret |= launch_proc(argv2);
 
 	ret |= !(launch_proc(argv3));

lib/librte_eal/common/eal_common_proc.c

@@ -1236,9 +1236,9 @@ rte_mp_reply(struct rte_mp_msg *msg, const char *peer)
 
 /* Internally, the status of the mp feature is represented as a three-state:
  * - "unknown" as long as no secondary process attached to a primary process
- *   and there was no call to __rte_mp_disable yet,
+ *   and there was no call to rte_mp_disable yet,
  * - "enabled" as soon as a secondary process attaches to a primary process,
- * - "disabled" when a primary process successfully called __rte_mp_disable,
+ * - "disabled" when a primary process successfully called rte_mp_disable,
  */
 enum mp_status {
 	MP_STATUS_UNKNOWN,
@@ -1263,7 +1263,7 @@ set_mp_status(enum mp_status status)
 }
 
 bool
-__rte_mp_disable(void)
+rte_mp_disable(void)
 {
 	return set_mp_status(MP_STATUS_DISABLED);
 }

lib/librte_eal/common/eal_common_thread.c

@@ -261,7 +261,7 @@ rte_thread_register(void)
 		rte_errno = EINVAL;
 		return -1;
 	}
-	if (!__rte_mp_disable()) {
+	if (!rte_mp_disable()) {
 		RTE_LOG(ERR, EAL, "Multiprocess in use, registering non-EAL threads is not supported.\n");
 		rte_errno = EINVAL;
 		return -1;

lib/librte_eal/common/eal_private.h

@@ -718,11 +718,6 @@ eal_get_internal_configuration(void);
 rte_usage_hook_t
 eal_get_application_usage_hook(void);
 
-/**
- * Mark primary process as not supporting multi-process.
- */
-bool __rte_mp_disable(void);
-
 /**
  * Instruct primary process that a secondary process wants to attach.
  */

lib/librte_eal/include/rte_eal.h

@@ -152,6 +152,20 @@ int rte_eal_cleanup(void);
  */
 int rte_eal_primary_proc_alive(const char *config_file_path);
 
+/**
+ * Disable multiprocess.
+ *
+ * This function can be called to indicate that multiprocess won't be used for
+ * the rest of the application life.
+ *
+ * @return
+ *   - true if called from a primary process that had no secondary processes
+ *     attached,
+ *   - false, otherwise.
+ */
+__rte_experimental
+bool rte_mp_disable(void);
+
 #define RTE_MP_MAX_FD_NUM	8    /* The max amount of fds */
 #define RTE_MP_MAX_NAME_LEN	64   /* The max length of action name */
 #define RTE_MP_MAX_PARAM_LEN	256  /* The max length of param */

lib/librte_eal/rte_eal_version.map

@@ -400,6 +400,7 @@ EXPERIMENTAL {
 	rte_lcore_callback_unregister;
 	rte_lcore_dump;
 	rte_lcore_iterate;
+	rte_mp_disable;
 	rte_thread_register;
 	rte_thread_unregister;
 };

lib/librte_eal/windows/eal.c

@@ -67,7 +67,7 @@ eal_proc_type_detect(void)
 }
 
 bool
-__rte_mp_disable(void)
+rte_mp_disable(void)
 {
 	return true;
 }