sctp_setprim
((struct sctp_setprim *)arg)->ssp_assoc_id = id;
struct sctp_setprim *ssp;
SCTP_CHECK_AND_CAST(ssp, optval, struct sctp_setprim, *optsize);
*optsize = sizeof(struct sctp_setprim);
struct sctp_setprim *spa;
SCTP_CHECK_AND_CAST(spa, optval, struct sctp_setprim, optsize);