Fix shutdown crash caused by modules being left open.

It is only safe to run ast_register_cleanup callbacks when all modules
have been unloaded.  Previously these callbacks were run during graceful
shutdown, making it possible to crash during shutdown.

ASTERISK-26513 #close

Change-Id: Ibfa635bb688d1227ec54aa211d90d6bd45052e21

include/asterisk/_private.h

@@ -16,6 +16,7 @@
 #define _ASTERISK__PRIVATE_H
 
 int load_modules(unsigned int);		/*!< Provided by loader.c */
+int modules_shutdown(void);		/*!< Provided by loader.c */
 int load_pbx(void);			/*!< Provided by pbx.c */
 int load_pbx_builtins(void);	/*!< Provided by pbx_builtins.c */
 int load_pbx_functions_cli(void);	/*!< Provided by pbx_functions.c */

include/asterisk/module.h

@@ -228,13 +228,6 @@ int ast_loader_register(int (*updater)(void));
  */
 int ast_loader_unregister(int (*updater)(void));
 
-/*!
- * \brief Run the unload() callback for all loaded modules
- *
- * This function should be called when Asterisk is shutting down gracefully.
- */
-void ast_module_shutdown(void);
-
 /*! 
  * \brief Match modules names for the Asterisk cli.
  * \param line Unused by this function, but this should be the line we are

main/asterisk.c

@@ -2010,8 +2010,9 @@ static void really_quit(int num, shutdown_nice_t niceness, int restart)
 	struct ast_json *json_object = NULL;
 	int run_cleanups = niceness >= SHUTDOWN_NICE;
 
-	if (run_cleanups) {
-		ast_module_shutdown();
+	if (run_cleanups && modules_shutdown()) {
+		ast_verb(0, "Some modules could not be unloaded, switching to fast shutdown\n");
+		run_cleanups = 0;
 	}
 
 	if (!restart) {

main/loader.c

@@ -607,7 +607,7 @@ static struct ast_module *load_dynamic_module(const char *resource_in, unsigned
 
 #endif
 
-void ast_module_shutdown(void)
+int modules_shutdown(void)
 {
 	struct ast_module *mod;
 	int somethingchanged = 1, final = 0;
@@ -655,7 +655,10 @@ void ast_module_shutdown(void)
 		}
 	} while (somethingchanged && !final);
 
+	final = AST_DLLIST_EMPTY(&module_list);
 	AST_DLLIST_UNLOCK(&module_list);
+
+	return !final;
 }
 
 int ast_unload_resource(const char *resource_name, enum ast_module_unload_mode force)