
static void qdisc_pkt_len_init(struct sk_buff *skb)
{
	const struct skb_shared_info *shinfo = skb_shinfo(skb);

	qdisc_skb_cb(skb)->pkt_len = skb->len;

	/* To get more precise estimation of bytes sent on wire,
	 * we add to pkt_len the headers size of all segments
	 */
	if (shinfo->gso_size && skb_transport_header_was_set(skb)) {
		unsigned int hdr_len;
		u16 gso_segs = shinfo->gso_segs;

		/* mac layer + network layer */
		hdr_len = skb_transport_header(skb) - skb_mac_header(skb);

		/* + transport layer */
		if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) {
			const struct tcphdr *th;
			struct tcphdr _tcphdr;

			th = skb_header_pointer(skb, skb_transport_offset(skb),
						sizeof(_tcphdr), &_tcphdr);
			if (likely(th))
				hdr_len += __tcp_hdrlen(th);
		} else {
			struct udphdr _udphdr;

			if (skb_header_pointer(skb, skb_transport_offset(skb),
					       sizeof(_udphdr), &_udphdr))
				hdr_len += sizeof(struct udphdr);
		}

		if (shinfo->gso_type & SKB_GSO_DODGY)
			gso_segs = DIV_ROUND_UP(skb->len - hdr_len,
						shinfo->gso_size);

		qdisc_skb_cb(skb)->pkt_len += (gso_segs - 1) * hdr_len;
	}
Unknown