static inline struct hlist_bl_head *in_lookup_hash(const struct dentry *parent,
					unsigned int hash)
{
	hash += (unsigned long) parent / L1_CACHE_BYTES;
	return in_lookup_hashtable + hash_32(hash, IN_LOOKUP_SHIFT);
}

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.