Subject: Re: [PATCH net-next] nfp: VF rate limit support

From: Jakub Kicinski <[email-masked]>
Date: Mon, 25 Apr 2022 16:53:21 -0700

On Fri, 22 Apr 2022 15:19:45 +0200 Simon Horman wrote:
> +	if (max_tx_rate > 0 || min_tx_rate > 0) {
> +		if (max_tx_rate > 0 && max_tx_rate < min_tx_rate) {
> +			nfp_warn(app->cpp, "min-tx-rate exceeds max_tx_rate.\n");
> +			return -EINVAL;
> +		}

This check should be moved to the core, I reckon.

> +		if (max_tx_rate > NFP_NET_VF_RATE_MAX || min_tx_rate > NFP_NET_VF_RATE_MAX) {

Please wrap the lines at 80 chars, it's actually going to be easier 
to read here.

> +			nfp_warn(app->cpp, "tx-rate exceeds 0x%x.\n", NFP_NET_VF_RATE_MAX);

Does it really make sense to print the rate as hex?

> +			return -EINVAL;
> +		}

> @@ -261,5 +294,18 @@ int nfp_app_get_vf_config(struct net_device *netdev, int vf,
>  	ivi->trusted = FIELD_GET(NFP_NET_VF_CFG_CTRL_TRUST, flags);
>  	ivi->linkstate = FIELD_GET(NFP_NET_VF_CFG_CTRL_LINK_STATE, flags);
>  
> +	err = nfp_net_sriov_check(app, vf, NFP_NET_VF_CFG_MB_CAP_RATE, "rate");
> +	if (!err) {
> +		rate = readl(app->pf->vfcfg_tbl2 + vf_offset + NFP_NET_VF_CFG_RATE);
> +
> +		ivi->max_tx_rate = FIELD_GET(NFP_NET_VF_CFG_MAX_RATE, rate);
> +		ivi->min_tx_rate = FIELD_GET(NFP_NET_VF_CFG_MIN_RATE, rate);
> +
> +		if (ivi->max_tx_rate == NFP_NET_VF_RATE_MAX)
> +			ivi->max_tx_rate = 0;

If rate == NFP_NET_VF_RATE_MAX means unset then the check on set should
disallow it, IOW:

	if (max_tx_rate >= NFP_NET_VF_RATE_MAX || 
            min_tx_rate >= NFP_NET_VF_RATE_MAX) {
		nfp_war(...

no?

> +		if (ivi->min_tx_rate == NFP_NET_VF_RATE_MAX)
> +			ivi->max_tx_rate = 0;

*squint* you check min and clear max, is this intentional?