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

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Message-ID: <nluliyurnbpf44vonqfcr37d5jlbv3avz75sqqnexonjhddztu@7bdewwkepieo>
Date: Wed, 29 Oct 2025 16:45:00 +0000
From: Dragos Tatulea <dtatulea@...dia.com>
To: Simon Horman <horms@...nel.org>, Tariq Toukan <tariqt@...dia.com>
Cc: Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Andrew Lunn <andrew+netdev@...n.ch>, 
	"David S. Miller" <davem@...emloft.net>, Saeed Mahameed <saeedm@...dia.com>, 
	Leon Romanovsky <leon@...nel.org>, Mark Bloch <mbloch@...dia.com>, netdev@...r.kernel.org, 
	linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org, Gal Pressman <gal@...dia.com>
Subject: Re: [PATCH net 2/3] net/mlx5e: SHAMPO, Fix skb size check for 64K
 pages

On Wed, Oct 29, 2025 at 03:50:41PM +0000, Simon Horman wrote:
> On Tue, Oct 28, 2025 at 08:47:18AM +0200, Tariq Toukan wrote:
> > From: Dragos Tatulea <dtatulea@...dia.com>
> > 
> > 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.
>
Yep. Will fix on respin.

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

Thanks for the review Simon!

Thanks,
Dragos