RDMA/hns: Fix 0-length sge calculation error

One RC SQ WQE can store 2 sges but UD can't, so ignore 2 valid sges of
wr.sglist for RC which have been filled in WQE before setting extended
sge.  Either of RC and UD can not contain 0-length sges, so these 0-length
sges should be skipped.

Fixes: 54d6638 ("RDMA/hns: Optimize WQE buffer size calculating process")
Link: https://lore.kernel.org/r/1606558959-48510-2-git-send-email-liweihang@huawei.com
Signed-off-by: Lang Cheng <chenglang@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Author: larrch

drivers/infiniband/hw/hns/hns_roce_hw_v2.c

@@ -214,25 +214,20 @@ static int fill_ext_sge_inl_data(struct hns_roce_qp *qp,
 	return 0;
 }
 
-static void set_extend_sge(struct hns_roce_qp *qp, const struct ib_send_wr *wr,
-			   unsigned int *sge_ind, unsigned int valid_num_sge)
+static void set_extend_sge(struct hns_roce_qp *qp, struct ib_sge *sge,
+			   unsigned int *sge_ind, unsigned int cnt)
 {
 	struct hns_roce_v2_wqe_data_seg *dseg;
-	unsigned int cnt = valid_num_sge;
-	struct ib_sge *sge = wr->sg_list;
 	unsigned int idx = *sge_ind;
 
-	if (qp->ibqp.qp_type == IB_QPT_RC || qp->ibqp.qp_type == IB_QPT_UC) {
-		cnt -= HNS_ROCE_SGE_IN_WQE;
-		sge += HNS_ROCE_SGE_IN_WQE;
-	}
-
 	while (cnt > 0) {
 		dseg = hns_roce_get_extend_sge(qp, idx & (qp->sge.sge_cnt - 1));
-		set_data_seg_v2(dseg, sge);
-		idx++;
+		if (likely(sge->length)) {
+			set_data_seg_v2(dseg, sge);
+			idx++;
+			cnt--;
+		}
 		sge++;
-		cnt--;
 	}
 
 	*sge_ind = idx;
@@ -340,7 +335,8 @@ static int set_rwqe_data_seg(struct ib_qp *ibqp, const struct ib_send_wr *wr,
 			}
 		}
 
-		set_extend_sge(qp, wr, sge_ind, valid_num_sge);
+		set_extend_sge(qp, wr->sg_list + i, sge_ind,
+			       valid_num_sge - HNS_ROCE_SGE_IN_WQE);
 	}
 
 	roce_set_field(rc_sq_wqe->byte_16,
@@ -503,7 +499,7 @@ static inline int set_ud_wqe(struct hns_roce_qp *qp,
 	if (ret)
 		return ret;
 
-	set_extend_sge(qp, wr, &curr_idx, valid_num_sge);
+	set_extend_sge(qp, wr->sg_list, &curr_idx, valid_num_sge);
 
 	/*
 	 * The pipeline can sequentially post all valid WQEs into WQ buffer,