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Message-ID: <20260201040151-mutt-send-email-mst@kernel.org>
Date: Sun, 1 Feb 2026 04:05:02 -0500
From: "Michael S. Tsirkin" <mst@...hat.com>
To: chia-yu.chang@...ia-bell-labs.com
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Subject: Re: [PATCH v1 net-next 2/3] net: hns3/mlx5e: avoid corrupting CWR
flag when receiving GRO packet
On Sat, Jan 31, 2026 at 11:55:09PM +0100, chia-yu.chang@...ia-bell-labs.com wrote:
> From: Chia-Yu Chang <chia-yu.chang@...ia-bell-labs.com>
>
> In Accurate ECN, ACE counter (AE, ECE, CWR flags) changes only when new
> CE packets arrive, while setting SKB_GSO_TCP_ECN in case of not knowing
> the ECN variant can result in header change that corrupts the ACE field.
> The new flag SKB_GSO_TCP_ACCECN is to prevent SKB_GSO_TCP_ECN or
> NETIF_F_TSO_ECN offloading to be used because they would corrupt CWR
> flag somewhere.
>
> Signed-off-by: Chia-Yu Chang <chia-yu.chang@...ia-bell-labs.com>
Not my driver, but a better format is something along the lines of:
Currently .... this is wrong because ... as the result .... fix this by ...
so that ....
the coding style does say that you should use the imperative form.
> ---
> drivers/net/ethernet/hisilicon/hns3/hns3_enet.c | 2 +-
> drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 4 ++--
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
> index a47464a22751..3a1cf4335477 100644
> --- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
> +++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
> @@ -3897,7 +3897,7 @@ static int hns3_gro_complete(struct sk_buff *skb, u32 l234info)
>
> skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
> if (th->cwr)
> - skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
> + skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ACCECN;
>
> if (l234info & BIT(HNS3_RXD_GRO_FIXID_B))
> skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_FIXEDID;
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> index 1fc3720d2201..d174f83478a3 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> @@ -1311,7 +1311,7 @@ static void mlx5e_shampo_update_ipv4_tcp_hdr(struct mlx5e_rq *rq, struct iphdr *
> skb->csum_offset = offsetof(struct tcphdr, check);
>
> if (tcp->cwr)
> - skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
> + skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ACCECN;
> }
>
> static void mlx5e_shampo_update_ipv6_tcp_hdr(struct mlx5e_rq *rq, struct ipv6hdr *ipv6,
> @@ -1332,7 +1332,7 @@ static void mlx5e_shampo_update_ipv6_tcp_hdr(struct mlx5e_rq *rq, struct ipv6hdr
> skb->csum_offset = offsetof(struct tcphdr, check);
>
> if (tcp->cwr)
> - skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
> + skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ACCECN;
> }
>
> static void mlx5e_shampo_update_hdr(struct mlx5e_rq *rq, struct mlx5_cqe64 *cqe, bool match)
> --
> 2.34.1
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