Re: [PATCH v2] flow_dissector: Fix vlan header offset in __skb_flow_dissect

[David Miller]

From: YueHaibing <yuehaibing@xxxxxxxxxx>
Date: Mon, 24 Jun 2019 11:49:13 +0800

> @@ -998,6 +998,9 @@ bool __skb_flow_dissect(const struct net *net,
>  		    skb && skb_vlan_tag_present(skb)) {
>  			proto = skb->protocol;
>  		} else {
> +			if (dissector_vlan == FLOW_DISSECTOR_KEY_MAX)
> +				nhoff -= sizeof(*vlan);
> +

But this is wrong when we are being called via eth_get_headlen(), in
that case nhoff will be sizeof(struct ethhdr).