+/**
+ * tomoyo_update_policy - Update an entry for exception policy.
+ *
+ * @new_entry: Pointer to "struct tomoyo_acl_info".
+ * @size: Size of @new_entry in bytes.
+ * @is_delete: True if it is a delete request.
+ * @list: Pointer to "struct list_head".
+ * @check_duplicate: Callback function to find duplicated entry.
+ *
+ * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+int tomoyo_update_policy(struct tomoyo_acl_head *new_entry, const int size,
+ bool is_delete, struct list_head *list,
+ bool (*check_duplicate) (const struct tomoyo_acl_head
+ *,
+ const struct tomoyo_acl_head
+ *))
+{
+ int error = is_delete ? -ENOENT : -ENOMEM;
+ struct tomoyo_acl_head *entry;
+
+ if (mutex_lock_interruptible(&tomoyo_policy_lock))
+ return -ENOMEM;
+ list_for_each_entry_rcu(entry, list, list) {
+ if (!check_duplicate(entry, new_entry))
+ continue;
+ entry->is_deleted = is_delete;
+ error = 0;
+ break;
+ }
+ if (error && !is_delete) {
+ entry = tomoyo_commit_ok(new_entry, size);
+ if (entry) {
+ list_add_tail_rcu(&entry->list, list);
+ error = 0;
+ }
+ }
+ mutex_unlock(&tomoyo_policy_lock);
+ return error;
+}
+