IB/ipath: Fix PSN update for RC retries

This patch fixes a number of bugs with updating the PSN for retries of
RC requests.

Signed-off-by: Bryan O'Sullivan <bryan.osullivan@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

diff --git a/drivers/infiniband/hw/ipath/ipath_rc.c b/drivers/infiniband/hw/ipath/ipath_rc.c
index 2e4d544957afd124f2a94d61d359fab71fefb064..d6aa14afa268ae61f3652abad7fbf88549a6083e 100644 (file)
--- a/drivers/infiniband/hw/ipath/ipath_rc.c
+++ b/drivers/infiniband/hw/ipath/ipath_rc.c
@@ -444,7 +444,7 @@ int ipath_make_rc_req(struct ipath_qp *qp,
                        qp->s_psn = wqe->lpsn + 1;
                else {
                        qp->s_psn++;
-                       if ((int)(qp->s_psn - qp->s_next_psn) > 0)
+                       if (ipath_cmp24(qp->s_psn, qp->s_next_psn) > 0)
                                qp->s_next_psn = qp->s_psn;
                }
                /*
@@ -471,7 +471,7 @@ int ipath_make_rc_req(struct ipath_qp *qp,
                /* FALLTHROUGH */
        case OP(SEND_MIDDLE):
                bth2 = qp->s_psn++ & IPATH_PSN_MASK;
-               if ((int)(qp->s_psn - qp->s_next_psn) > 0)
+               if (ipath_cmp24(qp->s_psn, qp->s_next_psn) > 0)
                        qp->s_next_psn = qp->s_psn;
                ss = &qp->s_sge;
                len = qp->s_len;
@@ -507,7 +507,7 @@ int ipath_make_rc_req(struct ipath_qp *qp,
                /* FALLTHROUGH */
        case OP(RDMA_WRITE_MIDDLE):
                bth2 = qp->s_psn++ & IPATH_PSN_MASK;
-               if ((int)(qp->s_psn - qp->s_next_psn) > 0)
+               if (ipath_cmp24(qp->s_psn, qp->s_next_psn) > 0)
                        qp->s_next_psn = qp->s_psn;
                ss = &qp->s_sge;
                len = qp->s_len;
@@ -546,7 +546,7 @@ int ipath_make_rc_req(struct ipath_qp *qp,
                qp->s_state = OP(RDMA_READ_REQUEST);
                hwords += sizeof(ohdr->u.rc.reth) / sizeof(u32);
                bth2 = qp->s_psn++ & IPATH_PSN_MASK;
-               if ((int)(qp->s_psn - qp->s_next_psn) > 0)
+               if (ipath_cmp24(qp->s_psn, qp->s_next_psn) > 0)
                        qp->s_next_psn = qp->s_psn;
                ss = NULL;
                len = 0;
@@ -779,7 +779,7 @@ void ipath_restart_rc(struct ipath_qp *qp, u32 psn, struct ib_wc *wc)
        if (wqe->wr.opcode == IB_WR_RDMA_READ)
                dev->n_rc_resends++;
        else
-               dev->n_rc_resends += (int)qp->s_psn - (int)psn;
+               dev->n_rc_resends += (qp->s_psn - psn) & IPATH_PSN_MASK;
 
        reset_psn(qp, psn);
        tasklet_hi_schedule(&qp->s_task);
@@ -915,15 +915,19 @@ static int do_rc_ack(struct ipath_qp *qp, u32 aeth, u32 psn, int opcode)
                if (qp->s_last == qp->s_cur) {
                        if (++qp->s_cur >= qp->s_size)
                                qp->s_cur = 0;
+                       qp->s_last = qp->s_cur;
+                       if (qp->s_last == qp->s_tail)
+                               break;
                        wqe = get_swqe_ptr(qp, qp->s_cur);
                        qp->s_state = OP(SEND_LAST);
                        qp->s_psn = wqe->psn;
+               } else {
+                       if (++qp->s_last >= qp->s_size)
+                               qp->s_last = 0;
+                       if (qp->s_last == qp->s_tail)
+                               break;
+                       wqe = get_swqe_ptr(qp, qp->s_last);
                }
-               if (++qp->s_last >= qp->s_size)
-                       qp->s_last = 0;
-               wqe = get_swqe_ptr(qp, qp->s_last);
-               if (qp->s_last == qp->s_tail)
-                       break;
        }
 
        switch (aeth >> 29) {
@@ -935,6 +939,18 @@ static int do_rc_ack(struct ipath_qp *qp, u32 aeth, u32 psn, int opcode)
                        list_add_tail(&qp->timerwait,
                                      &dev->pending[dev->pending_index]);
                        spin_unlock(&dev->pending_lock);
+                       /*
+                        * If we get a partial ACK for a resent operation,
+                        * we can stop resending the earlier packets and
+                        * continue with the next packet the receiver wants.
+                        */
+                       if (ipath_cmp24(qp->s_psn, psn) <= 0) {
+                               reset_psn(qp, psn + 1);
+                               tasklet_hi_schedule(&qp->s_task);
+                       }
+               } else if (ipath_cmp24(qp->s_psn, psn) <= 0) {
+                       qp->s_state = OP(SEND_LAST);
+                       qp->s_psn = psn + 1;
                }
                ipath_get_credit(qp, aeth);
                qp->s_rnr_retry = qp->s_rnr_retry_cnt;
@@ -945,22 +961,23 @@ static int do_rc_ack(struct ipath_qp *qp, u32 aeth, u32 psn, int opcode)
 
        case 1:         /* RNR NAK */
                dev->n_rnr_naks++;
+               if (qp->s_last == qp->s_tail)
+                       goto bail;
                if (qp->s_rnr_retry == 0) {
-                       if (qp->s_last == qp->s_tail)
-                               goto bail;
-
                        wc.status = IB_WC_RNR_RETRY_EXC_ERR;
                        goto class_b;
                }
                if (qp->s_rnr_retry_cnt < 7)
                        qp->s_rnr_retry--;
-               if (qp->s_last == qp->s_tail)
-                       goto bail;
 
                /* The last valid PSN is the previous PSN. */
                update_last_psn(qp, psn - 1);
 
-               dev->n_rc_resends += (int)qp->s_psn - (int)psn;
+               if (wqe->wr.opcode == IB_WR_RDMA_READ)
+                       dev->n_rc_resends++;
+               else
+                       dev->n_rc_resends +=
+                               (qp->s_psn - psn) & IPATH_PSN_MASK;
 
                reset_psn(qp, psn);
 
@@ -971,26 +988,20 @@ static int do_rc_ack(struct ipath_qp *qp, u32 aeth, u32 psn, int opcode)
                goto bail;
 
        case 3:         /* NAK */
-               /* The last valid PSN seen is the previous request's. */
-               if (qp->s_last != qp->s_tail)
-                       update_last_psn(qp, wqe->psn - 1);
+               if (qp->s_last == qp->s_tail)
+                       goto bail;
+               /* The last valid PSN is the previous PSN. */
+               update_last_psn(qp, psn - 1);
                switch ((aeth >> IPATH_AETH_CREDIT_SHIFT) &
                        IPATH_AETH_CREDIT_MASK) {
                case 0: /* PSN sequence error */
                        dev->n_seq_naks++;
                        /*
-                        * Back up to the responder's expected PSN.  XXX
+                        * Back up to the responder's expected PSN.
                         * Note that we might get a NAK in the middle of an
                         * RDMA READ response which terminates the RDMA
                         * READ.
                         */
-                       if (qp->s_last == qp->s_tail)
-                               break;
-
-                       if (ipath_cmp24(psn, wqe->psn) < 0)
-                               break;
-
-                       /* Retry the request. */
                        ipath_restart_rc(qp, psn, &wc);
                        break;