FRMR_IS_FREE
if (cmpxchg(&frmr->fr_state, FRMR_IS_FREE, FRMR_IS_INUSE) != FRMR_IS_FREE) {
rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_FREE);
} while (frmr->fr_state != FRMR_IS_FREE);
frmr->fr_state = FRMR_IS_FREE;