res_pjsip_exten_state,res_pjsip_mwi: Allow unload on shutdown

Commit f66f77f last year prevents the res_pjsip_exten_state and
res_pjsip_mwi modules from unloading due to possible pjproject
asserts if the modules are reloaded. A side effect of the
implementation is that the taskprocessors these modules use aren't
being released. When asterisk is doing a graceful shutdown, it
waits AST_TASKPROCESSOR_SHUTDOWN_MAX_WAIT seconds for all
taskprocessors to stop but since those 2 modules don't release
theirs, the shutdown hangs for that amount of time.

This change allows the modules to be unloaded and their resources to
be released when ast_shutdown_final is true.

Resolves: #379

res/res_pjsip_exten_state.c

@@ -973,33 +973,35 @@ static int publisher_stop(struct ast_sip_outbound_publish_client *client)
 
 static int unload_module(void)
 {
-#if 0
-	ast_sip_unregister_event_publisher_handler(&dialog_publisher);
-	ast_sip_unregister_subscription_handler(&dialog_handler);
-	ast_sip_unregister_event_publisher_handler(&presence_publisher);
-	ast_sip_unregister_subscription_handler(&presence_handler);
-
-	ast_extension_state_del(0, exten_state_publisher_state_cb);
-
-	ast_taskprocessor_unreference(publish_exten_state_serializer);
-	publish_exten_state_serializer = NULL;
-
-	ao2_cleanup(publishers);
-	publishers = NULL;
-
-	return 0;
-#else
-	/* If we were allowed to unload, the above is what we would do.
+	/*
 	 * pjsip_evsub_register_pkg is called by ast_sip_register_subscription_handler
 	 * but there is no corresponding unregister function, so unloading
 	 * a module does not remove the event package. If this module is ever
 	 * loaded again, then pjproject will assert and cause a crash.
-	 * For that reason, we must not be allowed to unload, but if
-	 * a pjsip_evsub_unregister_pkg API is added in the future
-	 * then we should go back to unloading the module as intended.
+	 * For that reason, we must only be allowed to unload when
+	 * asterisk is shutting down.  If a pjsip_evsub_unregister_pkg
+	 * API is added in the future then we should go back to unloading
+	 * the module as intended.
 	 */
-	return -1;
-#endif
+
+	if (ast_shutdown_final()) {
+		ast_sip_unregister_event_publisher_handler(&dialog_publisher);
+		ast_sip_unregister_subscription_handler(&dialog_handler);
+		ast_sip_unregister_event_publisher_handler(&presence_publisher);
+		ast_sip_unregister_subscription_handler(&presence_handler);
+
+		ast_extension_state_del(0, exten_state_publisher_state_cb);
+
+		ast_taskprocessor_unreference(publish_exten_state_serializer);
+		publish_exten_state_serializer = NULL;
+
+		ao2_cleanup(publishers);
+		publishers = NULL;
+
+		return 0;
+	} else {
+		return -1;
+	}
 }
 
 static int load_module(void)

res/res_pjsip_mwi.c

@@ -1524,43 +1524,45 @@ static int reload(void)
 
 static int unload_module(void)
 {
-#if 0
-	struct ao2_container *unsolicited_mwi;
+	/*
+	 * pjsip_evsub_register_pkg is called by ast_sip_register_subscription_handler
+	 * but there is no corresponding unregister function, so unloading
+	 * a module does not remove the event package. If this module is ever
+	 * loaded again, then pjproject will assert and cause a crash.
+	 * For that reason, we must only be allowed to unload when
+	 * asterisk is shutting down.  If a pjsip_evsub_unregister_pkg
+	 * API is added in the future then we should go back to unloading
+	 * the module as intended.
+	 */
 
-	ast_sorcery_observer_remove(ast_sip_get_sorcery(), "global", &global_observer);
-	ast_sorcery_observer_remove(ast_sip_get_sorcery(), "contact", &mwi_contact_observer);
+	if (ast_shutdown_final()) {
+		struct ao2_container *unsolicited_mwi;
 
-	unsolicited_mwi = ao2_global_obj_replace(mwi_unsolicited, NULL);
-	if (unsolicited_mwi) {
-		ao2_callback(unsolicited_mwi, OBJ_UNLINK | OBJ_NODATA | OBJ_MULTIPLE, unsubscribe, NULL);
-		ao2_ref(unsolicited_mwi, -1);
-	}
+		ast_sorcery_observer_remove(ast_sip_get_sorcery(), "global", &global_observer);
+		ast_sorcery_observer_remove(ast_sip_get_sorcery(), "contact", &mwi_contact_observer);
 
-	ao2_global_obj_release(mwi_solicited);
+		unsolicited_mwi = ao2_global_obj_replace(mwi_unsolicited, NULL);
+		if (unsolicited_mwi) {
+			ao2_callback(unsolicited_mwi, OBJ_UNLINK | OBJ_NODATA | OBJ_MULTIPLE, unsubscribe, NULL);
+			ao2_ref(unsolicited_mwi, -1);
+		}
 
-	if (ast_serializer_pool_destroy(mwi_serializer_pool)) {
-		ast_log(LOG_WARNING, "Unload incomplete. Try again later\n");
-		return -1;
-	}
-	mwi_serializer_pool = NULL;
+		ao2_global_obj_release(mwi_solicited);
 
-	ast_sip_unregister_subscription_handler(&mwi_handler);
+		if (ast_serializer_pool_destroy(mwi_serializer_pool)) {
+			ast_log(LOG_WARNING, "Unload incomplete. Try again later\n");
+			return -1;
+		}
+		mwi_serializer_pool = NULL;
 
-	ast_free(default_voicemail_extension);
-	default_voicemail_extension = NULL;
-	return 0;
-#else
-	/* If we were allowed to unload, the above is what we would do.
-	 * pjsip_evsub_register_pkg is called by ast_sip_register_subscription_handler
-	 * but there is no corresponding unregister function, so unloading
-	 * a module does not remove the event package. If this module is ever
-	 * loaded again, then pjproject will assert and cause a crash.
-	 * For that reason, we must not be allowed to unload, but if
-	 * a pjsip_evsub_unregister_pkg API is added in the future
-	 * then we should go back to unloading the module as intended.
-	 */
-	return -1;
-#endif
+		ast_sip_unregister_subscription_handler(&mwi_handler);
+
+		ast_free(default_voicemail_extension);
+		default_voicemail_extension = NULL;
+		return 0;
+	} else {
+		return -1;
+	}
 }
 
 static int load_module(void)