1 files changed, 19 insertions, 9 deletions

diff --git a/drivers/infiniband/hw/mlx4/qp.c b/drivers/infiniband/hw/mlx4/qp.c
index 39167a797f99..a91cb4c3fa5c 100644
--- a/drivers/infiniband/hw/mlx4/qp.c
+++ b/drivers/infiniband/hw/mlx4/qp.c
@@ -1462,7 +1462,8 @@ static void __set_data_seg(struct mlx4_wqe_data_seg *dseg, struct ib_sge *sg)
 }
 
 static int build_lso_seg(struct mlx4_wqe_lso_seg *wqe, struct ib_send_wr *wr,
-                         struct mlx4_ib_qp *qp, unsigned *lso_seg_len)
+                         struct mlx4_ib_qp *qp, unsigned *lso_seg_len,
+                         __be32 *lso_hdr_sz)
 {
         unsigned halign = ALIGN(sizeof *wqe + wr->wr.ud.hlen, 16);
 
@@ -1479,12 +1480,8 @@ static int build_lso_seg(struct mlx4_wqe_lso_seg *wqe, struct ib_send_wr *wr,
 
         memcpy(wqe->header, wr->wr.ud.header, wr->wr.ud.hlen);
 
-        /* make sure LSO header is written before overwriting stamping */
-        wmb();
-
-        wqe->mss_hdr_size = cpu_to_be32((wr->wr.ud.mss - wr->wr.ud.hlen) << 16 |
-                                        wr->wr.ud.hlen);
-
+        *lso_hdr_sz  = cpu_to_be32((wr->wr.ud.mss - wr->wr.ud.hlen) << 16 |
+                                   wr->wr.ud.hlen);
         *lso_seg_len = halign;
         return 0;
 }
@@ -1518,6 +1515,9 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
         int uninitialized_var(stamp);
         int uninitialized_var(size);
         unsigned uninitialized_var(seglen);
+        __be32 dummy;
+        __be32 *lso_wqe;
+        __be32 uninitialized_var(lso_hdr_sz);
         int i;
 
         spin_lock_irqsave(&qp->sq.lock, flags);
@@ -1525,6 +1525,8 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
         ind = qp->sq_next_wqe;
 
         for (nreq = 0; wr; ++nreq, wr = wr->next) {
+                lso_wqe = &dummy;
+
                 if (mlx4_wq_overflow(&qp->sq, nreq, qp->ibqp.send_cq)) {
                         err = -ENOMEM;
                         *bad_wr = wr;
@@ -1606,11 +1608,12 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
                         size += sizeof (struct mlx4_wqe_datagram_seg) / 16;
 
                         if (wr->opcode == IB_WR_LSO) {
-                                err = build_lso_seg(wqe, wr, qp, &seglen);
+                                err = build_lso_seg(wqe, wr, qp, &seglen, &lso_hdr_sz);
                                 if (unlikely(err)) {
                                         *bad_wr = wr;
                                         goto out;
                                 }
+                                lso_wqe = (__be32 *) wqe;
                                 wqe  += seglen;
                                 size += seglen / 16;
                         }
@@ -1652,6 +1655,14 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
                 for (i = wr->num_sge - 1; i >= 0; --i, --dseg)
                         set_data_seg(dseg, wr->sg_list + i);
 
+                /*
+                 * Possibly overwrite stamping in cacheline with LSO
+                 * segment only after making sure all data segments
+                 * are written.
+                 */
+                wmb();
+                *lso_wqe = lso_hdr_sz;
+
                 ctrl->fence_size = (wr->send_flags & IB_SEND_FENCE ?
                                     MLX4_WQE_CTRL_FENCE : 0) | size;
 
@@ -1686,7 +1697,6 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
                         stamp_send_wqe(qp, stamp, size * 16);
                         ind = pad_wraparound(qp, ind);
                 }
-
         }
 
 out: