Re: [PATCH net-next v8 1/5] net/sched: Introduce tc block netdev tracking infra

[Ido Schimmel <idosch@idosch.org>]

On Tue, Dec 19, 2023 at 03:16:19PM -0300, Victor Nogueira wrote:
> +static int qdisc_block_add_dev(struct Qdisc *sch, struct net_device *dev,
> +			       struct netlink_ext_ack *extack)
> +{
> +	const struct Qdisc_class_ops *cl_ops = sch->ops->cl_ops;
> +	struct tcf_block *block;
> +	int err;
> +
> +	block = cl_ops->tcf_block(sch, TC_H_MIN_INGRESS, NULL);

Another problem, shouldn't there be a check that these operations are
actually implemented? The following now crashes with a NULL pointer
dereference:

# tc qdisc replace dev swp1 root handle 1: tbf rate 1Mbit burst 256k limit 1M

> +	if (block) {
> +		err = xa_insert(&block->ports, dev->ifindex, dev, GFP_KERNEL);
> +		if (err) {
> +			NL_SET_ERR_MSG(extack,
> +				       "ingress block dev insert failed");
> +			return err;
> +		}
> +	}
> +
> +	block = cl_ops->tcf_block(sch, TC_H_MIN_EGRESS, NULL);
> +	if (block) {
> +		err = xa_insert(&block->ports, dev->ifindex, dev, GFP_KERNEL);
> +		if (err) {
> +			NL_SET_ERR_MSG(extack,
> +				       "Egress block dev insert failed");
> +			goto err_out;
> +		}
> +	}
> +
> +	return 0;
> +
> +err_out:
> +	block = cl_ops->tcf_block(sch, TC_H_MIN_INGRESS, NULL);
> +	if (block)
> +		xa_erase(&block->ports, dev->ifindex);
> +
> +	return err;
> +}
> +
>  static int qdisc_block_indexes_set(struct Qdisc *sch, struct nlattr **tca,
>  				   struct netlink_ext_ack *extack)
>  {
> @@ -1350,6 +1387,10 @@ static struct Qdisc *qdisc_create(struct net_device *dev,
>  	qdisc_hash_add(sch, false);
>  	trace_qdisc_create(ops, dev, parent);
>  
> +	err = qdisc_block_add_dev(sch, dev, extack);
> +	if (err)
> +		goto err_out4;
> +
>  	return sch;
>  
>  err_out4: