Re: [PATCH net-next 11/15] ethtool: set device ring sizes with RINGS_SET request

[Jakub Kicinski <kuba@kernel.org>]

On Wed, 11 Mar 2020 22:40:58 +0100 (CET) Michal Kubecek wrote:
> +int ethnl_set_rings(struct sk_buff *skb, struct genl_info *info)
> +{
> +	struct nlattr *tb[ETHTOOL_A_RINGS_MAX + 1];
> +	struct ethtool_ringparam ringparam = {};
> +	struct ethnl_req_info req_info = {};
> +	const struct nlattr *err_attr;
> +	const struct ethtool_ops *ops;
> +	struct net_device *dev;
> +	bool mod = false;
> +	int ret;
> +
> +	ret = nlmsg_parse(info->nlhdr, GENL_HDRLEN, tb,
> +			  ETHTOOL_A_RINGS_MAX, rings_set_policy,
> +			  info->extack);
> +	if (ret < 0)
> +		return ret;
> +	ret = ethnl_parse_header_dev_get(&req_info,
> +					 tb[ETHTOOL_A_RINGS_HEADER],
> +					 genl_info_net(info), info->extack,
> +					 true);
> +	if (ret < 0)
> +		return ret;
> +	dev = req_info.dev;
> +	ops = dev->ethtool_ops;
> +	if (!ops->get_ringparam || !ops->set_ringparam)
> +		return -EOPNOTSUPP;

Leaking the dev reference here?

> +
> +	rtnl_lock();
> +	ret = ethnl_ops_begin(dev);
> +	if (ret < 0)
> +		goto out_rtnl;
> +	ops->get_ringparam(dev, &ringparam);
> +
> +	ethnl_update_u32(&ringparam.rx_pending, tb[ETHTOOL_A_RINGS_RX], &mod);
> +	ethnl_update_u32(&ringparam.rx_mini_pending,
> +			 tb[ETHTOOL_A_RINGS_RX_MINI], &mod);
> +	ethnl_update_u32(&ringparam.rx_jumbo_pending,
> +			 tb[ETHTOOL_A_RINGS_RX_JUMBO], &mod);
> +	ethnl_update_u32(&ringparam.tx_pending, tb[ETHTOOL_A_RINGS_TX], &mod);
> +	ret = 0;
> +	if (!mod)
> +		goto out_ops;
> +
> +	/* ensure new ring parameters are within limits */
> +	if (ringparam.rx_pending > ringparam.rx_max_pending)
> +		err_attr = tb[ETHTOOL_A_RINGS_RX];
> +	else if (ringparam.rx_mini_pending > ringparam.rx_mini_max_pending)
> +		err_attr = tb[ETHTOOL_A_RINGS_RX_MINI];
> +	else if (ringparam.rx_jumbo_pending > ringparam.rx_jumbo_max_pending)
> +		err_attr = tb[ETHTOOL_A_RINGS_RX_JUMBO];
> +	else if (ringparam.tx_pending > ringparam.tx_max_pending)
> +		err_attr = tb[ETHTOOL_A_RINGS_TX];
> +	else
> +		err_attr = NULL;
> +	if (err_attr) {
> +		ret = -EINVAL;
> +		NL_SET_ERR_MSG_ATTR(info->extack, err_attr,
> +				    "requested ring size exceeeds maximum");
> +		goto out_ops;
> +	}
> +
> +	ret = dev->ethtool_ops->set_ringparam(dev, &ringparam);
> +
> +out_ops:
> +	ethnl_ops_complete(dev);
> +out_rtnl:
> +	rtnl_unlock();
> +	dev_put(dev);
> +	return ret;
> +}