On 6/9/20 8:00 AM, Eric Dumazet wrote:
>
>
> 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);
Maybe not qdisc_drop() (qdisc drop counters are already updated)
but at least kfree_skb() so that drop monitor is not fooled.
> else
> consume_skb(skb);
>
>> +
>> + return ret;
>> +}
>> +
>> static void fq_check_throttled(struct fq_sched_data *q, u64 now)
>> {
>> unsigned long sample;
>>
>
>
