static void __d_rehash(struct dentry *entry)
{
	struct hlist_bl_head *b = d_hash(entry->d_name.hash);
	BUG_ON(!d_unhashed(entry));
	hlist_bl_lock(b);
	hlist_bl_add_head_rcu(&entry->d_hash, b);
	hlist_bl_unlock(b);
}

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.