Re: [PATCH] net/mlx5: avoid setting kernel MTU if not needed

[David Marchand <david.marchand@redhat.com>]

Hello,

On Wed, May 28, 2025 at 11:36 AM Maxime Coquelin
<maxime.coquelin@redhat.com> wrote:
>
> This patch checks whether the Kernel MTU has the same value
> as the requested one at port configuration time, and skip
> setting it if it is the same.
>
> Doing this, we can avoid the application to require
> NET_ADMIN capability, as in v23.11.
>
> Fixes: 10859ecf09c4 ("net/mlx5: fix MTU configuration")
> Cc: stable@dpdk.org
>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>
> Hi Dariuz,
>
> I set priv->mtu as it is done after the mlx5_set_mtu() call,
> but I'm not sure it is necessary, as is the existing call to
> mlx5_get_mtu() because it seems done in mlx5_dev_spawn().

It seems there were some back and forth on this priv->mtu topic
between Nelio and other devs in the past.

Atm, I don't see the need for keeping such a cached mtu value in priv.
There is only one user of the value, and it is for configuration
operation that can do a query to the kernel.


-- 
David Marchand