svn commit: r359654 - head/sys/dev/mlx5/mlx5_en

[Hans Petter Selasky]

Author: hselasky
Date: Mon Apr  6 09:45:49 2020
New Revision: 359654
URL: https://svnweb.freebsd.org/changeset/base/359654

Log:
  Ensure a minimum inline size of 16 bytes in mlx5en(4).
  
  This includes 14 bytes of ethernet header and 2 bytes of VLAN header.
  
  This allows for making assumptions about the inline size limit
  in the fast transmit path later on.
  
  Use a signed integer variable to catch underflow.
  
  MFC after:	1 week
  Sponsored by:	Mellanox Technologies

Modified:
  head/sys/dev/mlx5/mlx5_en/mlx5_en_main.c

Modified: head/sys/dev/mlx5/mlx5_en/mlx5_en_main.c
==============================================================================
--- head/sys/dev/mlx5/mlx5_en/mlx5_en_main.c	Mon Apr  6 09:41:22 2020	(r359653)
+++ head/sys/dev/mlx5/mlx5_en/mlx5_en_main.c	Mon Apr  6 09:45:49 2020	(r359654)
@@ -3523,15 +3523,19 @@ mlx5e_check_required_hca_cap(struct mlx5_core_dev *mde
 static u16
 mlx5e_get_max_inline_cap(struct mlx5_core_dev *mdev)
 {
-	uint32_t bf_buf_size = (1U << MLX5_CAP_GEN(mdev, log_bf_reg_size)) / 2U;
+	const int min_size = ETHER_VLAN_ENCAP_LEN + ETHER_HDR_LEN;
+	const int max_size = MLX5E_MAX_TX_INLINE;
+	const int bf_buf_size =
+	    ((1U << MLX5_CAP_GEN(mdev, log_bf_reg_size)) / 2U) -
+	    (sizeof(struct mlx5e_tx_wqe) - 2);
 
-	bf_buf_size -= sizeof(struct mlx5e_tx_wqe) - 2;
-
-	/* verify against driver hardware limit */
-	if (bf_buf_size > MLX5E_MAX_TX_INLINE)
-		bf_buf_size = MLX5E_MAX_TX_INLINE;
-
-	return (bf_buf_size);
+	/* verify against driver limits */
+	if (bf_buf_size > max_size)
+		return (max_size);
+	else if (bf_buf_size < min_size)
+		return (min_size);
+	else
+		return (bf_buf_size);
 }
 
 static int