netdev - Re: [PATCH net-next v10 07/12] virtio_net: Implement layer 2 ethtool flow rules

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Message-ID: <aRtYRhKK8lbvREcy@horms.kernel.org>
Date: Mon, 17 Nov 2025 17:15:50 +0000
From: Simon Horman <horms@...nel.org>
To: Daniel Jurgens <danielj@...dia.com>
Cc: netdev@...r.kernel.org, mst@...hat.com, jasowang@...hat.com,
	pabeni@...hat.com, virtualization@...ts.linux.dev, parav@...dia.com,
	shshitrit@...dia.com, yohadt@...dia.com, xuanzhuo@...ux.alibaba.com,
	eperezma@...hat.com, shameerali.kolothum.thodi@...wei.com,
	jgg@...pe.ca, kevin.tian@...el.com, kuba@...nel.org,
	andrew+netdev@...n.ch, edumazet@...gle.com
Subject: Re: [PATCH net-next v10 07/12] virtio_net: Implement layer 2 ethtool
 flow rules

On Wed, Nov 12, 2025 at 01:34:30PM -0600, Daniel Jurgens wrote:

...

> +static int setup_classifier(struct virtnet_ff *ff, struct virtnet_classifier *c)
> +{
> +	int err;
> +
> +	err = xa_alloc(&ff->classifiers, &c->id, c,
> +		       XA_LIMIT(0, le32_to_cpu(ff->ff_caps->classifiers_limit) - 1),
> +		       GFP_KERNEL);

Hi Daniel,

I am wondering if some sort of bounds checking should be done for
classifiers_limit. E.g. if it is 0, then this will set the
maximum limit to -1 (UINT_MAX), which seems somewhat large,
assuming classifiers_limit of 0 doesn't mean unlimited.

Flagged by Claude Code with https://github.com/masoncl/review-prompts/

> +	if (err)
> +		return err;
> +
> +	err = virtio_admin_obj_create(ff->vdev,
> +				      VIRTIO_NET_RESOURCE_OBJ_FF_CLASSIFIER,
> +				      c->id,
> +				      VIRTIO_ADMIN_GROUP_TYPE_SELF,
> +				      0,
> +				      &c->classifier,
> +				      c->size);
> +	if (err)
> +		goto err_xarray;
> +
> +	return 0;
> +
> +err_xarray:
> +	xa_erase(&ff->classifiers, c->id);
> +
> +	return err;
> +}

...

> +static int virtnet_ethtool_flow_insert(struct virtnet_ff *ff,
> +				       struct ethtool_rx_flow_spec *fs,
> +				       u16 curr_queue_pairs)
> +{
> +	struct virtnet_ethtool_rule *eth_rule;
> +	int err;
> +
> +	if (!ff->ff_supported)
> +		return -EOPNOTSUPP;
> +
> +	err = validate_flow_input(ff, fs, curr_queue_pairs);
> +	if (err)
> +		return err;
> +
> +	eth_rule = kzalloc(sizeof(*eth_rule), GFP_KERNEL);
> +	if (!eth_rule)
> +		return -ENOMEM;
> +
> +	err = xa_alloc(&ff->ethtool.rules, &fs->location, eth_rule,
> +		       XA_LIMIT(0, le32_to_cpu(ff->ff_caps->rules_limit) - 1),
> +		       GFP_KERNEL);

Likewise for rules_limit.

> +	if (err)
> +		goto err_rule;
> +
> +	eth_rule->flow_spec = *fs;
> +
> +	err = build_and_insert(ff, eth_rule);
> +	if (err)
> +		goto err_xa;
> +
> +	return err;
> +
> +err_xa:
> +	xa_erase(&ff->ethtool.rules, eth_rule->flow_spec.location);
> +
> +err_rule:
> +	fs->location = RX_CLS_LOC_ANY;
> +	kfree(eth_rule);
> +
> +	return err;
> +}

...