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>

1 files changed, 38 insertions, 27 deletions

diff --git a/drivers/infiniband/hw/ipath/ipath_rc.c b/drivers/infiniband/hw/ipath/ipath_rc.c
index 2e4d544957af..d6aa14afa268 100644
--- 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;