bfa_q_prev
bfa_q_prev(_qe) = (struct list_head *) NULL; \
bfa_q_prev(bfa_q_next(*((struct list_head **) _qe))) = \
*((struct list_head **) (_qe)) = bfa_q_prev(_q); \
bfa_q_next(bfa_q_prev(*((struct list_head **) _qe))) = \
bfa_q_prev(_q) = bfa_q_prev(*(struct list_head **) _qe);\