Re: [PATCH net-next 1/5] ethtool: add support to set/get tx spare buf size

[Michal Kubecek <mkubecek@suse.cz>]

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On Wed, Aug 25, 2021 at 02:40:51PM +0800, Guangbin Huang wrote:
> From: Hao Chen <chenhao288@hisilicon.com>
> 
> Add support for ethtool to set/get tx spare buf size.
> 
> Signed-off-by: Hao Chen <chenhao288@hisilicon.com>
> Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
> ---
>  include/uapi/linux/ethtool.h | 1 +
>  net/ethtool/ioctl.c          | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
> index b6db6590baf0..266e95e4fb33 100644
> --- a/include/uapi/linux/ethtool.h
> +++ b/include/uapi/linux/ethtool.h
> @@ -231,6 +231,7 @@ enum tunable_id {
>  	ETHTOOL_RX_COPYBREAK,
>  	ETHTOOL_TX_COPYBREAK,
>  	ETHTOOL_PFC_PREVENTION_TOUT, /* timeout in msecs */
> +	ETHTOOL_TX_COPYBREAK_BUF_SIZE,
>  	/*
>  	 * Add your fresh new tunable attribute above and remember to update
>  	 * tunable_strings[] in net/ethtool/common.c
> diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
> index f2abc3152888..9fc801298fde 100644
> --- a/net/ethtool/ioctl.c
> +++ b/net/ethtool/ioctl.c
> @@ -2377,6 +2377,7 @@ static int ethtool_tunable_valid(const struct ethtool_tunable *tuna)
>  	switch (tuna->id) {
>  	case ETHTOOL_RX_COPYBREAK:
>  	case ETHTOOL_TX_COPYBREAK:
> +	case ETHTOOL_TX_COPYBREAK_BUF_SIZE:
>  		if (tuna->len != sizeof(u32) ||
>  		    tuna->type_id != ETHTOOL_TUNABLE_U32)
>  			return -EINVAL;
> -- 
> 2.8.1
> 

IMHO this illustrates quite well what I had in mind some time ago when
I expressed my doubts if the concept of tunables in this form still
makes sense as the main benefit - workaround for lack of extensibility
of the ioctl interface - is gone. With this patch, 3 out of 4 tunables
are related to copybreak and it would IMHO make sense to group them
together as attributes of a new message and ethtool subcommand.
Configuration of header split could also belong there when/if
implemented.

Michal

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