Re: [PATCH V4 net-next 4/6] ethtool: extend ringparam setting uAPI with rx_buf_len

On 25.10.2021 10:45:05, Jakub Kicinski wrote:

quoted

The approach Andrew suggested is two-fold. First introduce a "struct
ethtool_kringparam" that's only used inside the kernel, as "struct
ethtool_ringparam" is ABI. Then extend "struct ethtool_kringparam" as
needed.

Indeed, there are different ways to extend the API for drivers,
I think it comes down to personal taste. I find the "inheritance" 
models in C (kstruct usually contains the old struct as some "base")
awkward.

I don't think we have agreed-on best practice in the area.

From my point of view, if there already is an extension mainline:

| https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=f3ccfda19319

I'm more in the flavor for modeling other extensions the same way. Would
be more consistent to name the new struct "kernel_"ethtool_ringparam,
following the coalescing example:

| struct kernel_ethtool_ringparam {
|        __u32   rx_buf_len;
| };

regards,
Marc

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