implement a timer_list check before we return into the select() loop

this helps us to debug timer_list corruption

openbsc/src/select.c

@@ -78,6 +78,8 @@ int bsc_select_main(int polling)
 			FD_SET(ufd->fd, &exceptset);
 	}
 
+	bsc_timer_check();
+
 	if (!polling)
 		bsc_prepare_timers();
 	rc = select(maxfd+1, &readset, &writeset, &exceptset, polling ? &no_time : bsc_nearest_timer());

openbsc/src/timer.c

@@ -172,3 +172,14 @@ restart:
 
 	return work;
 }
+
+int bsc_timer_check(void)
+{
+	struct timer_list *timer;
+	int i;
+
+	llist_for_each_entry(timer, &timer_list, entry) {
+		i++;
+	}
+	return i;
+}