tracing/filters: return proper error code when writing filter file

- propagate return value of filter_add_pred() to the user

- return -ENOSPC but not -ENOMEM or -EINVAL when the filter array
  is full
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NTom Zanussi <tzanussi@gmail.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49E04CF0.3010105@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kernel/trace/trace_events.c

@@ -521,9 +521,10 @@ event_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
 		return cnt;
 	}
 
-	if (filter_add_pred(call, pred)) {
+	err = filter_add_pred(call, pred);
+	if (err < 0) {
 		filter_free_pred(pred);
-		return -EINVAL;
+		return err;
 	}
 
 	*ppos += cnt;
@@ -588,10 +589,11 @@ subsystem_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
 		return cnt;
 	}
 
-	if (filter_add_subsystem_pred(system, pred)) {
+	err = filter_add_subsystem_pred(system, pred);
+	if (err < 0) {
 		filter_free_subsystem_preds(system);
 		filter_free_pred(pred);
-		return -EINVAL;
+		return err;
 	}
 
 	*ppos += cnt;

kernel/trace/trace_events_filter.c

@@ -215,7 +215,7 @@ static int __filter_add_pred(struct ftrace_event_call *call,
 		}
 	}
 
-	return -ENOMEM;
+	return -ENOSPC;
 }
 
 static int is_string_field(const char *type)
@@ -319,7 +319,7 @@ int filter_add_subsystem_pred(struct event_subsystem *system,
 	}
 
 	if (i == MAX_FILTER_PRED)
-		return -EINVAL;
+		return -ENOSPC;
 
 	events_for_each(call) {
 		int err;