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

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

[Tariq Toukan]

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@mellanox.com>
Reviewed-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/wq.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Hi Dave,
Please queue for -stable v4.18.

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/wq.c b/drivers/net/ethernet/mellanox/mlx5/core/wq.c
index 86478a6b99c5..c8c315eb5128 100644
--- 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_dev *mdev, struct mlx5_wq_param *param,
 		      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),
-- 
1.8.3.1

Re: [PATCH net] net/mlx5: Fix SQ offset in QPs with small RQ

[David Miller]

From: Tariq Toukan <tariqt@mellanox.com>
Date: Mon,  3 Sep 2018 18:06:24 +0300

> 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@mellanox.com>
> Reviewed-by: Eran Ben Elisha <eranbe@mellanox.com>
> Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/wq.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> Hi Dave,
> Please queue for -stable v4.18.

Applied and queued up for -stable, thanks.