On 22 May 2018 01:45:13 CEST, Marcelo Ricardo Leitner
<marcelo.leit...@gmail.com> wrote:
>On Mon, May 21, 2018 at 10:35:58PM +0200, Toke Høiland-Jørgensen wrote:
>> +static u32 cake_overhead(struct cake_sched_data *q, const struct
>sk_buff *skb)
>> +{
>> + const struct skb_shared_info *shinfo = skb_shinfo(skb);
>> + unsigned int hdr_len, last_len = 0;
>> + u32 off = skb_network_offset(skb);
>> + u32 len = qdisc_pkt_len(skb);
>> + u16 segs = 1;
>> +
>> + q->avg_netoff = cake_ewma(q->avg_netoff, off << 16, 8);
>> +
>> + if (!shinfo->gso_size)
>> + return cake_calc_overhead(q, len, off);
>> +
>> + /* borrowed from qdisc_pkt_len_init() */
>> + 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 {
>
>I didn't see some code limiting GSO packets to just TCP or UDP. Is it
>safe to assume that this packet is an UDP one, and not SCTP or ESP,
>for example?
As the comment says, I nicked this from the qdisc init code.
So I assume it's safe? :)
>> + struct udphdr _udphdr;
>> +
>> + if (skb_header_pointer(skb, skb_transport_offset(skb),
>> + sizeof(_udphdr), &_udphdr))
>> + hdr_len += sizeof(struct udphdr);
>> + }
>> +
>> + if (unlikely(shinfo->gso_type & SKB_GSO_DODGY))
>> + segs = DIV_ROUND_UP(skb->len - hdr_len,
>> + shinfo->gso_size);
>> + else
>> + segs = shinfo->gso_segs;
>> +
>> + len = shinfo->gso_size + hdr_len;
>> + last_len = skb->len - shinfo->gso_size * (segs - 1);
>> +
>> + return (cake_calc_overhead(q, len, off) * (segs - 1) +
>> + cake_calc_overhead(q, last_len, off));
>> +}
>> +
