Re: [PATCH net-next 1/3] rtnetlink: add AF_PACKET multicast dumps

[David Ahern <dsahern@kernel.org>]

On 9/5/26 4:39 AM, Yuyang Huang wrote:
> +static int rtnl_dump_mcaddr(struct sk_buff *skb, struct netlink_callback *cb)
> +{
> +	struct net *net = sock_net(skb->sk);
> +	unsigned int flags = NLM_F_MULTI;
> +	struct {
> +		unsigned long ifindex;
> +		int addr_idx;
> +	} *ctx = (void *)cb->ctx;
> +	struct net_device *dev;
> +	int ifindex = 0;
> +	int err = 0;
> +
> +	if (cb->strict_check) {

this is new code. It should only work with strict checking.

> +		err = rtnl_valid_dump_mcaddr_req(cb->nlh, cb->extack,
> +						 &ifindex);
> +		if (err < 0)
> +			return err;
> +	}
> +
> +	rcu_read_lock();
> +
> +	if (ifindex) {
> +		cb->answer_flags |= NLM_F_DUMP_FILTERED;
> +		flags |= NLM_F_DUMP_FILTERED;
> +		dev = dev_get_by_index_rcu(net, ifindex);
> +		if (!dev) {
> +			err = -ENODEV;
> +			goto out;
> +		}
> +		err = rtnl_dump_mcaddr_dev(dev, skb, cb, &ctx->addr_idx, flags);
> +		goto out;
> +	}
> +
> +	for_each_netdev_dump(net, dev, ctx->ifindex) {
> +		err = rtnl_dump_mcaddr_dev(dev, skb, cb, &ctx->addr_idx,
> +					   flags);
> +		if (err < 0)
> +			break;
> +	}
> +out:
> +	rcu_read_unlock();
> +	return err;
> +}
> +
>  struct sk_buff *rtmsg_ifinfo_build_skb(int type, struct net_device *dev,
>  				       unsigned int change,
>  				       u32 event, gfp_t flags, int *new_nsid,