Question about AETH_NAK_PSN_SEQ_ERROR

[Chengguang Xu <cgxu519@mykernel.net>]

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;