On 6/9/20 7:09 AM, Willem de Bruijn wrote:
> From: Willem de Bruijn <will...@google.com>
>
> Optionally segment skbs on FQ enqueue, to later send segments at
> their individual delivery time.
>
> Segmentation on enqueue is new for FQ, but already happens in TBF,
> CAKE and netem.
>
> This slow patch should probably be behind a static_branch.
>
> Signed-off-by: Willem de Bruijn <will...@google.com>
> ---
> net/sched/sch_fq.c | 33 +++++++++++++++++++++++++++++++--
> 1 file changed, 31 insertions(+), 2 deletions(-)
>
> diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
> index 8f06a808c59a..a5e2c35bb557 100644
> --- a/net/sched/sch_fq.c
> +++ b/net/sched/sch_fq.c
> @@ -439,8 +439,8 @@ static bool fq_packet_beyond_horizon(const struct sk_buff
> *skb,
> return unlikely((s64)skb->tstamp > (s64)(q->ktime_cache + q->horizon));
> }
>
> -static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
> - struct sk_buff **to_free)
> +static int __fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
> + struct sk_buff **to_free)
> {
> struct fq_sched_data *q = qdisc_priv(sch);
> struct fq_flow *f;
> @@ -496,6 +496,35 @@ static int fq_enqueue(struct sk_buff *skb, struct Qdisc
> *sch,
> return NET_XMIT_SUCCESS;
> }
>
> +static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
> + struct sk_buff **to_free)
> +{
> + struct sk_buff *segs, *next;
> + int ret;
> +
> + if (likely(!skb_is_gso(skb) || !skb->sk ||
You also need to check sk_fullsock(skb->sk), otherwise KMSAN might be unhappy.
> + !skb->sk->sk_txtime_multi_release))
> + return __fq_enqueue(skb, sch, to_free);
> +
> + segs = skb_gso_segment_txtime(skb);
> + if (IS_ERR(segs))
> + return qdisc_drop(skb, sch, to_free);
> + if (!segs)
> + return __fq_enqueue(skb, sch, to_free);
> +
> + consume_skb(skb);
This needs to be qdisc_drop(skb, sch, to_free) if queue is full, see below.
> +
> + ret = NET_XMIT_DROP;
> + skb_list_walk_safe(segs, segs, next) {
> + skb_mark_not_on_list(segs);
> + qdisc_skb_cb(segs)->pkt_len = segs->len;
This seems to under-estimate bytes sent. See qdisc_pkt_len_init() for details.
> + if (__fq_enqueue(segs, sch, to_free) == NET_XMIT_SUCCESS)
> + ret = NET_XMIT_SUCCESS;
> + }
if (unlikely(ret == NET_XMIT_DROP))
qdisc_drop(skb, sch, to_free);
else
consume_skb(skb);
> +
> + return ret;
> +}
> +
> static void fq_check_throttled(struct fq_sched_data *q, u64 now)
> {
> unsigned long sample;
>
