net/mlx5e: XDP, Consider large muti-buffer packets in Striding RQ params calculations

Function mlx5e_rx_get_linear_stride_sz() returns PAGE_SIZE immediately
in case an XDP program is attached. The more accurate formula is
ALIGN(sz, PAGE_SIZE), to prevent two packets from residing on the same
page.

The assumption behind the current code is that sz <= PAGE_SIZE holds for
all cases with XDP program set.

This is true because it is being called from:
- 3 times from Striding RQ flows, in which XDP is not supported for such
  large packets.
- 1 time from Legacy RQ flow, under the condition
  mlx5e_rx_is_linear_skb().

No functional change here, just removing the implied assumption in
preparation for supporting XDP multi-buffer in Striding RQ.

Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/params.c b/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
index 31f3c6e..196862e 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
@@ -253,17 +253,20 @@ static u32 mlx5e_rx_get_linear_stride_sz(struct mlx5_core_dev *mdev,
                                         struct mlx5e_xsk_param *xsk,
                                         bool mpwqe)
 {
+       u32 sz;
+
        /* XSK frames are mapped as individual pages, because frames may come in
         * an arbitrary order from random locations in the UMEM.
         */
        if (xsk)
                return mpwqe ? 1 << mlx5e_mpwrq_page_shift(mdev, xsk) : PAGE_SIZE;
 
-       /* XDP in mlx5e doesn't support multiple packets per page. */
-       if (params->xdp_prog)
-               return PAGE_SIZE;
+       sz = roundup_pow_of_two(mlx5e_rx_get_linear_sz_skb(params, false));
 
-       return roundup_pow_of_two(mlx5e_rx_get_linear_sz_skb(params, false));
+       /* XDP in mlx5e doesn't support multiple packets per page.
+        * Do not assume sz <= PAGE_SIZE if params->xdp_prog is set.
+        */
+       return params->xdp_prog && sz < PAGE_SIZE ? PAGE_SIZE : sz;
 }
 
 static u8 mlx5e_mpwqe_log_pkts_per_wqe(struct mlx5_core_dev *mdev,