Re: [PATCH v4 net-next 2/7] net: ethtool: attach an XArray of custom RSS contexts to a netdevice

[Jacob Keller <jacob.e.keller@intel.com>]

On 9/27/2023 11:13 AM, edward.cree@amd.com wrote:
> From: Edward Cree <ecree.xilinx@gmail.com>
> 
> Each context stores the RXFH settings (indir, key, and hfunc) as well
>  as optionally some driver private data.
> Delete any still-existing contexts at netdev unregister time.
> 
> Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
> ---
>  include/linux/ethtool.h | 43 ++++++++++++++++++++++++++++++++++++++++-
>  net/core/dev.c          | 25 ++++++++++++++++++++++++
>  2 files changed, 67 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
> index 8aeefc0b4e10..bb11cb2f477d 100644
> --- a/include/linux/ethtool.h
> +++ b/include/linux/ethtool.h
> @@ -157,6 +157,43 @@ static inline u32 ethtool_rxfh_indir_default(u32 index, u32 n_rx_rings)
>  	return index % n_rx_rings;
>  }
>  
> +/**
> + * struct ethtool_rxfh_context - a custom RSS context configuration
> + * @indir_size: Number of u32 entries in indirection table
> + * @key_size: Size of hash key, in bytes
> + * @hfunc: RSS hash function identifier.  One of the %ETH_RSS_HASH_*
> + * @priv_size: Size of driver private data, in bytes
> + * @indir_no_change: indir was not specified at create time
> + * @key_no_change: hkey was not specified at create time
> + */
> +struct ethtool_rxfh_context {
> +	u32 indir_size;
> +	u32 key_size;
> +	u8 hfunc;
> +	u16 priv_size;
> +	u8 indir_no_change:1;
> +	u8 key_no_change:1;
> +	/* private: driver private data, indirection table, and hash key are
> +	 * stored sequentially in @data area.  Use below helpers to access.
> +	 */
> +	u8 data[] __aligned(sizeof(void *));
> +};

Is it not feasible to use container_of to get to private data for the
drivers? I guess this change in particular doesn't actually include any
users yet...