From: Christoph Paasch When gso_segs is left at 0, a number of assumptions will end up being incorrect throughout the stack. For example, in the GRO-path, we set NAPI_GRO_CB()->count to gso_segs. So, if a non-LRO'ed packet followed by an LRO'ed packet is being processed in GRO, the first one will have NAPI_GRO_CB()->count set to 1 and the next one to 0 (in dev_gro_receive()). Since commit 531d0d32de3e ("net/mlx5: Correctly set gso_size when LRO is used") these packets will get merged (as their gso_size now matches). So, we end up in gro_complete() with NAPI_GRO_CB()->count == 1 and thus don't call inet_gro_complete(). Meaning, checksum-validation in tcp_checksum_complete() will fail with a "hw csum failure". Even before the above mentioned commit, incorrect gso_segs means that other things like TCP's accounting of incoming packets (tp->segs_in, data_segs_in, rcv_ooopack) will be incorrect. Which means that if one does bytes_received/data_segs_in, the result will be bigger than the MTU. Fix this by initializing gso_segs correctly when LRO is used. Fixes: e586b3b0baee ("net/mlx5: Ethernet Datapath files") Reported-by: Gal Pressman Closes: https://lore.kernel.org/netdev/6583783f-f0fb-4fb1-a415-feec8155bc69@nvidia.com/ Signed-off-by: Christoph Paasch --- drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c index 7462514c7f3d1606339ede13a6207c1629ab65a3..da3e340c99b72ce27861cccaa5bd722c1b446a55 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c @@ -1567,6 +1567,7 @@ static inline void mlx5e_build_rx_skb(struct mlx5_cqe64 *cqe, unsigned int hdrlen = mlx5e_lro_update_hdr(skb, cqe, cqe_bcnt); skb_shinfo(skb)->gso_size = DIV_ROUND_UP(cqe_bcnt - hdrlen, lro_num_seg); + skb_shinfo(skb)->gso_segs = lro_num_seg; /* Subtract one since we already counted this as one * "regular" packet in mlx5e_complete_rx_cqe() */ --- base-commit: afd8c2c9e2e29c6c7705635bea2960593976dacc change-id: 20250729-mlx5_gso_segs-8e5ea2d4b9b0 Best regards, -- Christoph Paasch