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[PATCH 4.18 027/197] net/mlx5: Fix SQ offset in QPs with small RQ




4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tariq Toukan <tariqt@xxxxxxxxxxxx>

[ Upstream commit 639505d4397b8c654a8e2616f9cb70ece40c83f9 ]

Correct the formula for calculating the RQ page remainder,
which should be in byte granularity.  The result will be
non-zero only for RQs smaller than PAGE_SIZE, as an RQ size
is a power of 2.

Divide this by the SQ stride (MLX5_SEND_WQE_BB) to get the
SQ offset in strides granularity.

Fixes: d7037ad73daa ("net/mlx5: Fix QP fragmented buffer allocation")
Signed-off-by: Tariq Toukan <tariqt@xxxxxxxxxxxx>
Reviewed-by: Eran Ben Elisha <eranbe@xxxxxxxxxxxx>
Signed-off-by: Saeed Mahameed <saeedm@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/ethernet/mellanox/mlx5/core/wq.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/wq.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/wq.c
@@ -139,14 +139,15 @@ int mlx5_wq_qp_create(struct mlx5_core_d
 		      struct mlx5_wq_ctrl *wq_ctrl)
 {
 	u32 sq_strides_offset;
+	u32 rq_pg_remainder;
 	int err;
 
 	mlx5_fill_fbc(MLX5_GET(qpc, qpc, log_rq_stride) + 4,
 		      MLX5_GET(qpc, qpc, log_rq_size),
 		      &wq->rq.fbc);
 
-	sq_strides_offset =
-		((wq->rq.fbc.frag_sz_m1 + 1) % PAGE_SIZE) / MLX5_SEND_WQE_BB;
+	rq_pg_remainder   = mlx5_wq_cyc_get_byte_size(&wq->rq) % PAGE_SIZE;
+	sq_strides_offset = rq_pg_remainder / MLX5_SEND_WQE_BB;
 
 	mlx5_fill_fbc_offset(ilog2(MLX5_SEND_WQE_BB),
 			     MLX5_GET(qpc, qpc, log_sq_size),