[PATCH] IB/mthca: fix posting of first work request

Fix posting first WQE for mem-free HCAs: we need to link to previous
WQE even in that case.  While we're at it, simplify code for
Tavor-mode HCAs.  We don't really need the conditional test there
either; we can similarly always link to the previous WQE.

Based on Michael S. Tsirkin's analogous fix for userspace libmthca.

Signed-off-by: Roland Dreier <rolandd@cisco.com>

2 files changed, 28 insertions, 34 deletions

diff --git a/drivers/infiniband/hw/mthca/mthca_qp.c b/drivers/infiniband/hw/mthca/mthca_qp.c
index 2c883c1fd53a..eaa521857630 100644
--- a/drivers/infiniband/hw/mthca/mthca_qp.c
+++ b/drivers/infiniband/hw/mthca/mthca_qp.c
@@ -227,7 +227,6 @@ static void mthca_wq_init(struct mthca_wq *wq)
         wq->last_comp = wq->max - 1;
         wq->head      = 0;
         wq->tail      = 0;
-        wq->last      = NULL;
 }
 
 void mthca_qp_event(struct mthca_dev *dev, u32 qpn,
@@ -1103,6 +1102,9 @@ static int mthca_alloc_qp_common(struct mthca_dev *dev,
                 }
         }
 
+        qp->sq.last = get_send_wqe(qp, qp->sq.max - 1);
+        qp->rq.last = get_recv_wqe(qp, qp->rq.max - 1);
+
         return 0;
 }
 
@@ -1583,15 +1585,13 @@ int mthca_tavor_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
                         goto out;
                 }
 
-                if (prev_wqe) {
-                        ((struct mthca_next_seg *) prev_wqe)->nda_op =
-                                cpu_to_be32(((ind << qp->sq.wqe_shift) +
-                                             qp->send_wqe_offset) |
-                                            mthca_opcode[wr->opcode]);
-                        wmb();
-                        ((struct mthca_next_seg *) prev_wqe)->ee_nds =
-                                cpu_to_be32((size0 ? 0 : MTHCA_NEXT_DBD) | size);
-                }
+                ((struct mthca_next_seg *) prev_wqe)->nda_op =
+                        cpu_to_be32(((ind << qp->sq.wqe_shift) +
+                                     qp->send_wqe_offset) |
+                                    mthca_opcode[wr->opcode]);
+                wmb();
+                ((struct mthca_next_seg *) prev_wqe)->ee_nds =
+                        cpu_to_be32((size0 ? 0 : MTHCA_NEXT_DBD) | size);
 
                 if (!size0) {
                         size0 = size;
@@ -1688,13 +1688,11 @@ int mthca_tavor_post_receive(struct ib_qp *ibqp, struct ib_recv_wr *wr,
 
                 qp->wrid[ind] = wr->wr_id;
 
-                if (likely(prev_wqe)) {
-                        ((struct mthca_next_seg *) prev_wqe)->nda_op =
-                                cpu_to_be32((ind << qp->rq.wqe_shift) | 1);
-                        wmb();
-                        ((struct mthca_next_seg *) prev_wqe)->ee_nds =
-                                cpu_to_be32(MTHCA_NEXT_DBD | size);
-                }
+                ((struct mthca_next_seg *) prev_wqe)->nda_op =
+                        cpu_to_be32((ind << qp->rq.wqe_shift) | 1);
+                wmb();
+                ((struct mthca_next_seg *) prev_wqe)->ee_nds =
+                        cpu_to_be32(MTHCA_NEXT_DBD | size);
 
                 if (!size0)
                         size0 = size;
@@ -1905,15 +1903,13 @@ int mthca_arbel_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
                         goto out;
                 }
 
-                if (likely(prev_wqe)) {
-                        ((struct mthca_next_seg *) prev_wqe)->nda_op =
-                                cpu_to_be32(((ind << qp->sq.wqe_shift) +
-                                             qp->send_wqe_offset) |
-                                            mthca_opcode[wr->opcode]);
-                        wmb();
-                        ((struct mthca_next_seg *) prev_wqe)->ee_nds =
-                                cpu_to_be32(MTHCA_NEXT_DBD | size);
-                }
+                ((struct mthca_next_seg *) prev_wqe)->nda_op =
+                        cpu_to_be32(((ind << qp->sq.wqe_shift) +
+                                     qp->send_wqe_offset) |
+                                    mthca_opcode[wr->opcode]);
+                wmb();
+                ((struct mthca_next_seg *) prev_wqe)->ee_nds =
+                        cpu_to_be32(MTHCA_NEXT_DBD | size);
 
                 if (!size0) {
                         size0 = size;
diff --git a/drivers/infiniband/hw/mthca/mthca_srq.c b/drivers/infiniband/hw/mthca/mthca_srq.c
index 75cd2d84ef12..fe06cc0df936 100644
--- a/drivers/infiniband/hw/mthca/mthca_srq.c
+++ b/drivers/infiniband/hw/mthca/mthca_srq.c
@@ -189,7 +189,6 @@ int mthca_alloc_srq(struct mthca_dev *dev, struct mthca_pd *pd,
 
         srq->max      = attr->max_wr;
         srq->max_gs   = attr->max_sge;
-        srq->last     = NULL;
         srq->counter  = 0;
 
         if (mthca_is_memfree(dev))
@@ -264,6 +263,7 @@ int mthca_alloc_srq(struct mthca_dev *dev, struct mthca_pd *pd,
 
         srq->first_free = 0;
         srq->last_free  = srq->max - 1;
+        srq->last       = get_wqe(srq, srq->max - 1);
 
         return 0;
 
@@ -446,13 +446,11 @@ int mthca_tavor_post_srq_recv(struct ib_srq *ibsrq, struct ib_recv_wr *wr,
                         ((struct mthca_data_seg *) wqe)->addr = 0;
                 }
 
-                if (likely(prev_wqe)) {
-                        ((struct mthca_next_seg *) prev_wqe)->nda_op =
-                                cpu_to_be32((ind << srq->wqe_shift) | 1);
-                        wmb();
-                        ((struct mthca_next_seg *) prev_wqe)->ee_nds =
-                                cpu_to_be32(MTHCA_NEXT_DBD);
-                }
+                ((struct mthca_next_seg *) prev_wqe)->nda_op =
+                        cpu_to_be32((ind << srq->wqe_shift) | 1);
+                wmb();
+                ((struct mthca_next_seg *) prev_wqe)->ee_nds =
+                        cpu_to_be32(MTHCA_NEXT_DBD);
 
                 srq->wrid[ind]  = wr->wr_id;
                 srq->first_free = next_ind;