Re: [PATCH net] net/mlx5e: Update netdev features only after a successful ringparam set

[Tariq Toukan <tariqt@nvidia.com>]

On 18/10/2026 19:55, Nimrod Oren wrote:
> On 17/10/2026 3:54, Dimitri Daskalakis wrote:
>> From: Dimitri Daskalakis <daskald@meta.com>
>>
>> mlx5 couples HW-GRO with tcp-data-split. If a user sets rx-gro-hw on ->
>> tcp-data-split on -> rx-gro-hw off, the driver will leave HW-GRO on.
>> mlx5e_ethtool_set_tcp_data_split() calls netdev_update_features() when
>> tcp-data-split goes from enabled to disabled in case HW-GRO needs to be
>> released. mlx5e_fix_features() reads the new HDS config from
>> dev->cfg_pending, so HW-GRO is released before all ring parameters are
>> validated.
>>
>> If the subsequent call to mlx5e_ethtool_set_ringparam() fails, the
>> ethtool core discards the pending change and reports tcp-data-split
>> enabled. The device is no longer splitting, and subsequent ring changes
>> are blocked.
>>
>> Move the call to netdev_update_features() after
>> mlx5e_ethtool_set_ringparam() exits successfully.
>>
>> The issue was discovered by manual code inspection during review of
>> a change that stops mlx5 users from disabling tcp-data-split. It was
>> reproduced on a ConnectX-7 with ethtool alone.
>>
>> Steps to reproduce:
>> ethtool -K eth0 rx-gro-hw on
>> ethtool -G eth0 tcp-data-split on
>> ethtool -K eth0 rx-gro-hw off # HW-GRO kept on for tcp-data-split
>>
>> ethtool -G eth0 tcp-data-split off rx 1 # de-sync driver & kernel state
>>   netlink error: mlx5_core: rx (1) < min (16)
>>   netlink error: Invalid argument
>>
>> ethtool -G eth0 rx 1024 # valid ring changes are now blocked
>>   netlink error: mlx5_core: TCP-data-split is not supported when GRO HW is disabled
>>   netlink error: Invalid argument
>>
>> This is not a terminal state, users can recover by setting rx-gro-hw on.
>> With the fix, the failing ringparam set leaves rx-gro-hw on and later
>> ring changes succeed.
>>
>> Fixes: 46bcce5dfd33 ("net/mlx5e: Support ethtool tcp-data-split settings")
>> Reported-by: Björn Töpel <bjorn@kernel.org>
>> Closes: https://lore.kernel.org/87se2grw3d.fsf@all.your.base.are.belong.to.us/
>> Signed-off-by: Dimitri Daskalakis <daskald@meta.com>
> 
> Reviewed-by: Nimrod Oren <noren@nvidia.com>

Acked-by: Tariq Toukan <tariqt@nvidia.com>