static void copy_name(struct dentry *dentry, struct dentry *target)
{
	struct external_name *old_name = NULL;
	if (unlikely(dname_external(dentry)))
		old_name = external_name(dentry);
	if (unlikely(dname_external(target))) {
		atomic_inc(&external_name(target)->u.count);
		dentry->d_name = target->d_name;
	} else {
		memcpy(dentry->d_iname, target->d_name.name,
				target->d_name.len + 1);
		dentry->d_name.name = dentry->d_iname;
		dentry->d_name.hash_len = target->d_name.hash_len;
	}
	if (old_name && likely(atomic_dec_and_test(&old_name->u.count)))
		kfree_rcu(old_name, u.head);
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.