strmakedata
if ((error = strmakedata(iosize, uiop, stp, flags,
if ((error = strmakedata(iosize, uiop, stp, flags, &mp)) != 0) {
error = strmakedata(iosize, uiop, stp, flag, &mpdata);
extern int strmakedata(ssize_t *, struct uio *, stdata_t *, int32_t, mblk_t **);