Re: [PATCH net-next 06/12] ethtool: rss: don't report key if device doesn't support it

[Joe Damato <jdamato@fastly.com>]

On Thu, Aug 01, 2024 at 05:17:55PM -0700, Jakub Kicinski wrote:
> marvell/otx2 and mvpp2 do not support setting different
> keys for different RSS contexts. Contexts have separate
> indirection tables but key is shared with all other contexts.
> This is likely fine, indirection table is the most important
> piece.
> 
> Don't report the key-related parameters from such drivers.
> This prevents driver-errors, e.g. otx2 always writes
> the main key, even when user asks to change per-context key.
> The second reason is that without this change tracking
> the keys by the core gets complicated. Even if the driver
> correctly reject setting key with rss_context != 0,
> change of the main key would have to be reflected in
> the XArray for all additional contexts.
> 
> Since the additional contexts don't have their own keys
> not including the attributes (in Netlink speak) seems
> intuitive. ethtool CLI seems to deal with it just fine.

FWIW: I took a look at the ethtool source and I agree, but didn't
test it.

> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
>  .../net/ethernet/broadcom/bnxt/bnxt_ethtool.c |  1 +
>  drivers/net/ethernet/intel/ice/ice_ethtool.c  |  1 +
>  .../ethernet/mellanox/mlx5/core/en_ethtool.c  |  1 +
>  drivers/net/ethernet/sfc/ef100_ethtool.c      |  1 +
>  drivers/net/ethernet/sfc/ethtool.c            |  1 +
>  drivers/net/ethernet/sfc/siena/ethtool.c      |  1 +
>  include/linux/ethtool.h                       |  3 +++
>  net/ethtool/ioctl.c                           | 25 ++++++++++++++++---
>  net/ethtool/rss.c                             | 21 +++++++++++-----
>  9 files changed, 45 insertions(+), 10 deletions(-)

Reviewed-by: Joe Damato <jdamato@fastly.com>