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From: Saeed Mahameed <>
To: "David S. Miller" <>,
	Jakub Kicinski <>
Cc:, Tariq Toukan <>,
	Moshe Shemesh <>,
	Saeed Mahameed <>
Subject: [net 05/12] net/mlx5e: RX, Avoid possible data corruption when relaxed ordering and LRO combined
Date: Tue, 27 Jul 2021 16:20:43 -0700	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

From: Tariq Toukan <>

When HW aggregates packets for an LRO session, it writes the payload
of two consecutive packets of a flow contiguously, so that they usually
share a cacheline.

The first byte of a packet's payload is written immediately after
the last byte of the preceding packet.
In this flow, there are two consecutive write requests to the shared
1. Regular write for the earlier packet.
2. Read-modify-write for the following packet.

In case of relaxed-ordering on, these two writes might be re-ordered.
Using the end padding optimization (to avoid partial write for the last
cacheline of a packet) becomes problematic if the two writes occur
out-of-order, as the padding would overwrite payload that belongs to
the following packet, causing data corruption.

Avoid this by disabling the end padding optimization when both
LRO and relaxed-ordering are enabled.

Fixes: 17347d5430c4 ("net/mlx5e: Add support for PCI relaxed ordering")
Signed-off-by: Tariq Toukan <>
Reviewed-by: Moshe Shemesh <>
Signed-off-by: Saeed Mahameed <>
 drivers/net/ethernet/mellanox/mlx5/core/en/params.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/params.c b/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
index 150c8e82c738..2cbf18c967f7 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
@@ -471,6 +471,15 @@ static void mlx5e_build_rx_cq_param(struct mlx5_core_dev *mdev,
 	param->cq_period_mode = params->rx_cq_moderation.cq_period_mode;
+static u8 rq_end_pad_mode(struct mlx5_core_dev *mdev, struct mlx5e_params *params)
+	bool ro = pcie_relaxed_ordering_enabled(mdev->pdev) &&
+		MLX5_CAP_GEN(mdev, relaxed_ordering_write);
+	return ro && params->lro_en ?
 int mlx5e_build_rq_param(struct mlx5_core_dev *mdev,
 			 struct mlx5e_params *params,
 			 struct mlx5e_xsk_param *xsk,
@@ -508,7 +517,7 @@ int mlx5e_build_rq_param(struct mlx5_core_dev *mdev,
 	MLX5_SET(wq, wq, wq_type,          params->rq_wq_type);
-	MLX5_SET(wq, wq, end_padding_mode, MLX5_WQ_END_PAD_MODE_ALIGN);
+	MLX5_SET(wq, wq, end_padding_mode, rq_end_pad_mode(mdev, params));
 	MLX5_SET(wq, wq, log_wq_stride,
 		 mlx5e_get_rqwq_log_stride(params->rq_wq_type, ndsegs));
 	MLX5_SET(wq, wq, pd,               mdev->mlx5e_res.hw_objs.pdn);

  parent reply	other threads:[~2021-07-27 23:21 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-27 23:20 [pull request][net 00/12] mlx5 fixes 2021-07-27 Saeed Mahameed
2021-07-27 23:20 ` [net 01/12] net/mlx5: Fix flow table chaining Saeed Mahameed
2021-07-28  8:30   ` patchwork-bot+netdevbpf
2021-07-27 23:20 ` [net 02/12] net/mlx5e: Disable Rx ntuple offload for uplink representor Saeed Mahameed
2021-07-27 23:20 ` [net 03/12] net/mlx5: E-Switch, Set destination vport vhca id only when merged eswitch is supported Saeed Mahameed
2021-07-27 23:20 ` [net 04/12] net/mlx5: E-Switch, handle devcom events only for ports on the same device Saeed Mahameed
2021-07-27 23:20 ` Saeed Mahameed [this message]
2021-07-27 23:20 ` [net 06/12] net/mlx5e: Add NETIF_F_HW_TC to hw_features when HTB offload is available Saeed Mahameed
2021-07-27 23:20 ` [net 07/12] net/mlx5e: Consider PTP-RQ when setting RX VLAN stripping Saeed Mahameed
2021-07-27 23:20 ` [net 08/12] net/mlx5e: Fix page allocation failure for trap-RQ over SF Saeed Mahameed
2021-07-27 23:20 ` [net 09/12] net/mlx5e: Fix page allocation failure for ptp-RQ " Saeed Mahameed
2021-07-27 23:20 ` [net 10/12] net/mlx5: Unload device upon firmware fatal error Saeed Mahameed
2021-07-27 23:20 ` [net 11/12] net/mlx5e: Fix nullptr in mlx5e_hairpin_get_mdev() Saeed Mahameed
2021-07-27 23:20 ` [net 12/12] net/mlx5: Fix mlx5_vport_tbl_attr chain from u16 to u32 Saeed Mahameed

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