BTW, just for the archives' sake: inet_client_addr() and inet_client_port() also access MyProcPort, so they'd also have this issue, except that they're already marked parallel-restricted. So somebody just missed the server equivalents when marking the parallel safety of built-in functions.
contrib/sslinfo is also full of uses of MyProcPort, but all its functions are properly marked parallel-restricted. I did not see any other risky-looking uses of MyProcPort in a quick grep. regards, tom lane