Question about AETH_NAK_PSN_SEQ_ERROR

[Chengguang Xu <cgxu519@xxxxxxxxxxxx>]

Hello Folks,


There is a logic(below code) in check_ack() in rxe_comp.c,  the case 
(AETH_NAK_PSN_SEQ_ERROR)
indicates sending side received a nak ack which means opposite side had 
an psn seq error(expected psn < received psn).
I don't fully understand the comment(/* a nak implicitly acks all 
packets with psns before */) here,
could someone give me a hint for this?

Also, set qp->comp.psn as pkt->psn will skip some psns(from qp->comp.psn 
to pkt->psn) in the retry, is it correct?

Many thanks in advance!
Chengguang

-------------------------

  case AETH_NAK:
            switch (syn) {
            case AETH_NAK_PSN_SEQ_ERROR:
                /* a nak implicitly acks all packets with psns
                 * before
                 */
                if (psn_compare(pkt->psn, qp->comp.psn) > 0) {
                    rxe_counter_inc(rxe,
                            RXE_CNT_RCV_SEQ_ERR);
                    qp->comp.psn = pkt->psn;
                    if (qp->req.wait_psn) {
                        qp->req.wait_psn = 0;
                        rxe_run_task(&qp->req.task, 0);
                    }
                }
                return COMPST_ERROR_RETRY;