fix

Author: olsajiri

kernel/trace/ftrace.c

@@ -5960,17 +5960,6 @@ static void register_ftrace_direct_cb(struct rcu_head *rhp)
 	free_ftrace_hash(fhp);
 }
 
-static void reset_direct(struct ftrace_ops *ops, unsigned long addr)
-{
-	struct ftrace_hash *hash = ops->func_hash->filter_hash;
-
-	remove_direct_functions_hash(hash, addr);
-
-	/* cleanup for possible another register call */
-	ops->func = NULL;
-	ops->trampoline = 0;
-}
-
 static struct ftrace_hash *hash_from_ip(unsigned long ip, unsigned long addr)
 {
 	struct ftrace_hash *hash;
@@ -6132,6 +6121,18 @@ static struct ftrace_hash *hash_add(struct ftrace_hash *a, struct ftrace_hash *b
 	return NULL;
 }
 
+static void reset_direct_hash(struct ftrace_ops *ops, struct ftrace_hash **hashp)
+{
+	struct ftrace_hash *free_hash = direct_functions;
+
+	rcu_assign_pointer(direct_functions, *hashp);
+	*hashp = free_hash;
+
+	/* cleanup for possible another register call */
+	ops->func = NULL;
+	ops->trampoline = 0;
+}
+
 int update_ftrace_direct_add(struct ftrace_ops *ops, struct ftrace_hash *hash)
 {
 	struct ftrace_hash *filter_hash = NULL, *new_hash = NULL, *free_hash = NULL;
@@ -6189,6 +6190,9 @@ int update_ftrace_direct_add(struct ftrace_ops *ops, struct ftrace_hash *hash)
 		err = ftrace_update_ops(ops, filter_hash, EMPTY_HASH);
 	}
 
+	if (err)
+		reset_direct_hash(ops, &free_hash);
+
  out_unlock:
 	mutex_unlock(&direct_mutex);
 
@@ -6283,8 +6287,10 @@ int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash)
 		err = ftrace_update_ops(ops, filter_hash, EMPTY_HASH);
 	}
 
-	free_hash = direct_functions;
-	rcu_assign_pointer(direct_functions, new_hash);
+	if (!err) {
+		free_hash = direct_functions;
+		rcu_assign_pointer(direct_functions, new_hash);
+	}
 
  out_unlock:
 	mutex_unlock(&direct_mutex);