Canadian traveling through Shanghai airport to cruise port to work on ship sailing from Shanghai

Is a Visa required? Conflicting information from various sources for my circumstance. Do I need an entry permit each time I come back from a vacation? I fly from Canada into Pudong airport in Shanghai, to board the cruise ship within 24 hours that I work on. My ship sails from Shanghai to various ports in Japan and Korea. It does not go to any other Chinese port. It's an American cruise ship (Royal Caribbean) and I am a Canadian citizen. Thank you!