linux-kernel - Re: [PATCH net-next V2 1/2] net/mlx5e: RX, Drop oversized packets in non-linear mode

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Message-ID: <9d3d6128-41fb-4f72-acca-3bb9d6798e3c@intel.com>
Date: Wed, 4 Feb 2026 14:55:56 -0800
From: Jacob Keller <jacob.e.keller@...el.com>
To: Tariq Toukan <tariqt@...dia.com>, 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>
CC: Saeed Mahameed <saeedm@...dia.com>, Mark Bloch <mbloch@...dia.com>, "Leon
 Romanovsky" <leon@...nel.org>, <netdev@...r.kernel.org>,
	<linux-rdma@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Gal Pressman
	<gal@...dia.com>, Dragos Tatulea <dtatulea@...dia.com>, Cosmin Ratiu
	<cratiu@...dia.com>, Moshe Shemesh <moshe@...dia.com>
Subject: Re: [PATCH net-next V2 1/2] net/mlx5e: RX, Drop oversized packets in
 non-linear mode



On 2/2/2026 11:21 PM, Tariq Toukan wrote:
> From: Dragos Tatulea <dtatulea@...dia.com>
> 
> Currently the driver has an inconsistent behaviour between modes when it
> comes to oversized packets that are not dropped through the physical MTU
> check in HW. This can happen for Multi Host configurations where each
> port has a different MTU.
> 
> Current behavior:
> 
> 1) Striding RQ in linear mode drops the packet in SW and counts it
>     with oversize_pkts_sw_drop.
> 
> 2) Striding RQ in non-linear mode allows it like a normal packet.
> 
> 3) Legacy RQ can't receive oversized packets by design:
>     the RX WQE uses MTU sized packet buffers.
> 
> This inconsistency is not a violation of the netdev policy [1]
> but it is better to be consistent across modes.
> 
> This patch aligns (2) with (1) and (3). One exception is added for
> LRO: don't drop the oversized packet if it is an LRO packet.
> 

The doc also says that the preference is to drop packets, so this makes 
sense.

> As now rq->hw_mtu always needs to be updated during the MTU change flow,
> drop the reset avoidance optimization from mlx5e_change_mtu().
> 
> Extract the CQE LRO segments reading into a helper function as it
> is used twice now.
> 
> [1] Documentation/networking/netdevices.rst#L205
> 
> Signed-off-by: Dragos Tatulea <dtatulea@...dia.com>
> Signed-off-by: Tariq Toukan <tariqt@...dia.com>
> ---
Reviewed-by: Jacob Keller <jacob.e.keller@...el.com>