u32 rds_tcp_write_seq(struct rds_tcp_connection *tc)
{
	/* seq# of the last byte of data in tcp send buffer */
	return tcp_sk(tc->t_sock->sk)->write_seq;
}

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.