[S390] shutdown actions: save/return rc from init function

We always returned -EINVAL when setting of a shutdown action failed. This was
misleading, if for example the hardware did not support the shutdown action.
Now we save each shutdown action's init return code and return it when the
action is being set.
Signed-off-by: Frank Munzert <munzert@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/ipl.c

@@ -70,6 +70,7 @@ struct shutdown_action {
 	char *name;
 	void (*fn) (struct shutdown_trigger *trigger);
 	int (*init) (void);
+	int init_rc;
 };
 
 static char *ipl_type_str(enum ipl_type type)
@@ -1486,13 +1487,15 @@ static int set_trigger(const char *buf, struct shutdown_trigger *trigger,
 	int i;
 
 	for (i = 0; i < SHUTDOWN_ACTIONS_COUNT; i++) {
-		if (!shutdown_actions_list[i])
-			continue;
 		if (sysfs_streq(buf, shutdown_actions_list[i]->name)) {
+			if (shutdown_actions_list[i]->init_rc) {
+				return shutdown_actions_list[i]->init_rc;
+			} else {
 				trigger->action = shutdown_actions_list[i];
 				return len;
 			}
 		}
+	}
 	return -EINVAL;
 }
 
@@ -1640,8 +1643,8 @@ static void __init shutdown_actions_init(void)
 	for (i = 0; i < SHUTDOWN_ACTIONS_COUNT; i++) {
 		if (!shutdown_actions_list[i]->init)
 			continue;
-		if (shutdown_actions_list[i]->init())
-			shutdown_actions_list[i] = NULL;
+		shutdown_actions_list[i]->init_rc =
+			shutdown_actions_list[i]->init();
 	}
 }