IB/qib: Insure last cursor is updated prior to complete

This patch is a prerequisite for adding a separate lock
for post send.

The timing of updating s_last needs to be before returning
any send completion to avoid a race between a poll cq seeing
a completion and the post send checking for a full queue.

Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

diff --git a/drivers/infiniband/hw/qib/qib_rc.c b/drivers/infiniband/hw/qib/qib_rc.c
index 044525d9c8b86fee60275600cffa49c20de997a5..ce886b2ade74e58a4b4e08d1c8861ab687405b81 100644 (file)
--- a/drivers/infiniband/hw/qib/qib_rc.c
+++ b/drivers/infiniband/hw/qib/qib_rc.c
@@ -1008,10 +1008,18 @@ void qib_rc_send_complete(struct rvt_qp *qp, struct qib_ib_header *hdr)
                start_timer(qp);
 
        while (qp->s_last != qp->s_acked) {
+               u32 s_last;
+
                wqe = rvt_get_swqe_ptr(qp, qp->s_last);
                if (qib_cmp24(wqe->lpsn, qp->s_sending_psn) >= 0 &&
                    qib_cmp24(qp->s_sending_psn, qp->s_sending_hpsn) <= 0)
                        break;
+               s_last = qp->s_last;
+               if (++s_last >= qp->s_size)
+                       s_last = 0;
+               qp->s_last = s_last;
+               /* see post_send() */
+               barrier();
                for (i = 0; i < wqe->wr.num_sge; i++) {
                        struct rvt_sge *sge = &wqe->sg_list[i];
 
@@ -1028,8 +1036,6 @@ void qib_rc_send_complete(struct rvt_qp *qp, struct qib_ib_header *hdr)
                        wc.qp = &qp->ibqp;
                        rvt_cq_enter(ibcq_to_rvtcq(qp->ibqp.send_cq), &wc, 0);
                }
-               if (++qp->s_last >= qp->s_size)
-                       qp->s_last = 0;
        }
        /*
         * If we were waiting for sends to complete before resending,
@@ -1068,11 +1074,19 @@ static struct rvt_swqe *do_rc_completion(struct rvt_qp *qp,
         */
        if (qib_cmp24(wqe->lpsn, qp->s_sending_psn) < 0 ||
            qib_cmp24(qp->s_sending_psn, qp->s_sending_hpsn) > 0) {
+               u32 s_last;
+
                for (i = 0; i < wqe->wr.num_sge; i++) {
                        struct rvt_sge *sge = &wqe->sg_list[i];
 
                        rvt_put_mr(sge->mr);
                }
+               s_last = qp->s_last;
+               if (++s_last >= qp->s_size)
+                       s_last = 0;
+               qp->s_last = s_last;
+               /* see post_send() */
+               barrier();
                /* Post a send completion queue entry if requested. */
                if (!(qp->s_flags & RVT_S_SIGNAL_REQ_WR) ||
                    (wqe->wr.send_flags & IB_SEND_SIGNALED)) {
@@ -1084,8 +1098,6 @@ static struct rvt_swqe *do_rc_completion(struct rvt_qp *qp,
                        wc.qp = &qp->ibqp;
                        rvt_cq_enter(ibcq_to_rvtcq(qp->ibqp.send_cq), &wc, 0);
                }
-               if (++qp->s_last >= qp->s_size)
-                       qp->s_last = 0;
        } else
                this_cpu_inc(*ibp->rvp.rc_delayed_comp);
 

diff --git a/drivers/infiniband/hw/qib/qib_ruc.c b/drivers/infiniband/hw/qib/qib_ruc.c
index 56668cb3a3cfd89ec9033c2146092d72c01a2d44..2623684745f074d52b65c6fc8a9fe619ada0ab71 100644 (file)
--- a/drivers/infiniband/hw/qib/qib_ruc.c
+++ b/drivers/infiniband/hw/qib/qib_ruc.c
@@ -795,6 +795,13 @@ void qib_send_complete(struct rvt_qp *qp, struct rvt_swqe *wqe,
        if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_OR_FLUSH_SEND))
                return;
 
+       last = qp->s_last;
+       old_last = last;
+       if (++last >= qp->s_size)
+               last = 0;
+       qp->s_last = last;
+       /* See post_send() */
+       barrier();
        for (i = 0; i < wqe->wr.num_sge; i++) {
                struct rvt_sge *sge = &wqe->sg_list[i];
 
@@ -822,11 +829,6 @@ void qib_send_complete(struct rvt_qp *qp, struct rvt_swqe *wqe,
                             status != IB_WC_SUCCESS);
        }
 
-       last = qp->s_last;
-       old_last = last;
-       if (++last >= qp->s_size)
-               last = 0;
-       qp->s_last = last;
        if (qp->s_acked == old_last)
                qp->s_acked = last;
        if (qp->s_cur == old_last)