samples: cellular: mss: Fix for sporadically connection failure

conn_mgr event callback registration was called
after triggering the connection which sporadically
lead to hang waiting for a valid connection.

IRIS-10183

Signed-off-by: Pascal Hernandez <[email protected]>

Author: pascal-nordic

doc/nrf/releases_and_maturity/releases/release-notes-changelog.rst

@@ -378,6 +378,11 @@ Cellular samples
     * Support for environment evaluation using the ``link enveval`` command.
     * Support for NTN NB-IoT to the ``link sysmode`` and ``link edrx`` commands.
 
+* :ref:`nrf_cloud_multi_service` sample:
+
+  * Fixed an issue where sporadically the application was stuck waiting for the device to connect to the internet.
+    This was due to wrong :ref:`Connection Manager <zephyr:conn_mgr_overview>` initialization.
+
 Cryptography samples
 --------------------
 

samples/cellular/nrf_cloud_multi_service/src/cloud_connection.c

@@ -36,6 +36,7 @@ LOG_MODULE_REGISTER(cloud_connection, CONFIG_MULTI_SERVICE_LOG_LEVEL);
 #define CLOUD_READY			BIT(2)
 #define CLOUD_DISCONNECTED		BIT(3)
 #define DATE_TIME_KNOWN			BIT(4)
+#define L4_EVENT_MASK		(NET_EVENT_L4_CONNECTED | NET_EVENT_L4_DISCONNECTED)
 static K_EVENT_DEFINE(cloud_events);
 
 /* Atomic status flag tracking whether an initial association is in progress. */
@@ -550,7 +551,7 @@ static void cloud_event_handler(const struct nrf_cloud_evt *nrf_cloud_evt)
 #endif /* CONFIG_NRF_CLOUD_MQTT */
 
 /**
- * @brief Set up for the nRF Cloud connection (without connecting)
+ * @brief Set up for the nRF Cloud connection
  *
  * Sets up required event hooks and initializes the nrf_cloud library.
  *
@@ -560,24 +561,6 @@ static int setup_cloud(void)
 {
 	int err;
 
-	/* Register to be notified of network availability changes.
-	 *
-	 * If the chosen connectivity layer becomes ready instantaneously, it is possible that
-	 * L4_CONNECTED will be fired before reaching this function, in which case we will miss
-	 * the notification.
-	 *
-	 * If that is a serious concern, use SYS_INIT with priority 0 (less than
-	 * CONFIG_NET_CONNECTION_MANAGER_MONITOR_PRIORITY) to register this hook before conn_mgr
-	 * initializes.
-	 *
-	 * In reality, connectivity layers such as LTE take some time to go online, so registering
-	 * the hook here is fine.
-	 */
-	net_mgmt_init_event_callback(
-		&l4_callback, l4_event_handler, NET_EVENT_L4_CONNECTED | NET_EVENT_L4_DISCONNECTED
-	);
-	net_mgmt_add_event_callback(&l4_callback);
-
 	/* Register to be notified when the modem has figured out the current time. */
 	date_time_register_handler(date_time_event_handler);
 
@@ -648,6 +631,13 @@ void cloud_connection_thread_fn(void)
 {
 	long_led_pattern(LED_WAITING);
 
+	/* Setup handler for Zephyr NET Connection Manager events. */
+	net_mgmt_init_event_callback(&l4_callback, l4_event_handler, L4_EVENT_MASK);
+	net_mgmt_add_event_callback(&l4_callback);
+
+	/* Enable the connection manager for all interfaces and allow them to connect. */
+	conn_mgr_all_if_up(true);
+
 	LOG_INF("Enabling connectivity...");
 	conn_mgr_all_if_connect(true);