Subject: Re: [PATCH net-next v5 1/4] ethtool: provide customized dim profile management

From: Jakub Kicinski <[email-masked]>
Date: Tue, 9 Apr 2024 18:44:00 -0700

On Tue,  9 Apr 2024 20:03:21 +0800 Heng Qi wrote:
> +/**
> + * coalesce_put_profile - fill reply with a nla nest with four child nla nests.
> + * @skb: socket buffer the message is stored in
> + * @attr_type: nest attr type ETHTOOL_A_COALESCE_*X_*QE_PROFILE
> + * @profile: data passed to userspace
> + * @supported_params: modifiable parameters supported by the driver
> + *
> + * Put a dim profile nest attribute. Refer to ETHTOOL_A_MODERATIONS_MODERATION.

unfortunately kdoc got more picky and it also wants us to document
return values now, you gotta add something like

 * Returns: true if ..

actually this functions seems to return negative error codes as bool..

> +static bool coalesce_put_profile(struct sk_buff *skb, u16 attr_type,
> +				 const struct dim_cq_moder *profile,
> +				 u32 supported_params)
> +{
> +	struct nlattr *profile_attr, *moder_attr;
> +	bool valid = false;
> +	int i;
> +
> +	for (i = 0; i < NET_DIM_PARAMS_NUM_PROFILES; i++) {
> +		if (profile[i].usec || profile[i].pkts || profile[i].comps) {
> +			valid = true;
> +			break;
> +		}
> +	}
> +
> +	if (!valid || !(supported_params & attr_to_mask(attr_type)))
> +		return false;
> +
> +	profile_attr = nla_nest_start(skb, attr_type);
> +	if (!profile_attr)
> +		return -EMSGSIZE;
> +
> +	for (i = 0; i < NET_DIM_PARAMS_NUM_PROFILES; i++) {
> +		moder_attr = nla_nest_start(skb, ETHTOOL_A_MODERATIONS_MODERATION);
> +		if (!moder_attr)
> +			goto nla_cancel_profile;
> +
> +		if (nla_put_u16(skb, ETHTOOL_A_MODERATION_USEC, profile[i].usec) ||
> +		    nla_put_u16(skb, ETHTOOL_A_MODERATION_PKTS, profile[i].pkts) ||
> +		    nla_put_u16(skb, ETHTOOL_A_MODERATION_COMPS, profile[i].comps))

u16 in netlink is almost always the wrong choice, sizes are rounded 
up to 4B, anyway, let's use u32 at netlink level.