In this paper, we analyze the performance of a cognitive radio network where the secondary transmitter, besides its own transmission, occasionally relays the primary signal. It is assumed that the secondary transmitter employs the exhaustive service mode to transmit the secondary signal and multiple vacations to relay the primary signal. When assisting the primary transmitter, we assume that the secondary transmitter utilizes the decode-and-forward protocol to process the primary signal and forwards it to the primary receiver. Furthermore, the secondary transmitter has a finite buffer, the arriving packets of the secondary network are modeled as a Poisson process, and all channels are subject to Nakagami-m fading. Modeling the system as an M/G/1/K queueing system with exhaustive service and multiple vacations, using an embedded Markov chain approach to analyze the system, we obtain several key queueing performance indicators, i.e., the channel utilization, blocking probability, mean number of packets, and mean serving time of a packet in the system. The derived formulas are then utilized to evaluate the performance of the considered system.