Re: [PATCH net 2/3] net/mlx5e: SHAMPO, Fix skb size check for 64K pages

[Simon Horman]

On Tue, Oct 28, 2025 at 08:47:18AM +0200, Tariq Toukan wrote:
> From: Dragos Tatulea <dtatulea@xxxxxxxxxx>
> 
> mlx5e_hw_gro_skb_has_enough_space() uses a formula to check if there is
> enough space in the skb frags to store more data. This formula is
> incorrect for 64K page sizes and it triggers early GRO session
> termination because the first fragment will blow up beyond
> GRO_LEGACY_MAX_SIZE.
> 
> This patch adds a special case for page sizes >= GRO_LEGACY_MAX_SIZE
> (64K) which will uses the skb->data_len instead. Within this context,
> this check will be safe from fragment overflow.

The above mentions skb->data_len, but the code uses skb->len.

Also, I think it would be worth describing why this is safe
in this context.

> 
> It is expected that the if statement will be optimized out as the
> check is done with constants.
> 
> Fixes: 92552d3abd32 ("net/mlx5e: HW_GRO cqe handler implementation")
> Signed-off-by: Dragos Tatulea <dtatulea@xxxxxxxxxx>
> Signed-off-by: Tariq Toukan <tariqt@xxxxxxxxxx>

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