VMCI_DG_HEADERSIZE
link_msg.hdr.payload_size = sizeof(link_msg) - VMCI_DG_HEADERSIZE;
unlink_msg.hdr.payload_size = sizeof(unlink_msg) - VMCI_DG_HEADERSIZE;
VMCI_DG_HEADERSIZE;
check_msg->payload_size = msg_size - VMCI_DG_HEADERSIZE;
if (remaining_bytes < VMCI_DG_HEADERSIZE) {
alloc_msg->hdr.payload_size = msg_size - VMCI_DG_HEADERSIZE;
#define VMCI_DG_SIZE(_dg) (VMCI_DG_HEADERSIZE + (size_t)(_dg)->payload_size)