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Date: Fri, 15 Feb 2013 06:18:49 -0800
From: Eric Dumazet <eric.dumazet@...il.com>
To: Jiri Pirko <jiri@...nulli.us>
Cc: netdev@...r.kernel.org, davem@...emloft.net, edumazet@...gle.com,
jhs@...atatu.com, kuznet@....inr.ac.ru, j.vimal@...il.com
Subject: Re: [patch net-next RFC] tbf: handle gso skbs properly
On Fri, 2013-02-15 at 13:44 +0100, Jiri Pirko wrote:
> According to Eric's suggestion, when gso skb can't be sent in one mtu
> time, resegment it.
>
> Note that helper will be moved to sch_api.c probably so it can be used
> by other code.
>
> Also, I'm not sure similar patch to this can be done for act_police. I
> have to look at that more closely.
>
> Thanks for review.
>
> Signed-off-by: Jiri Pirko <jiri@...nulli.us>
> ---
> include/net/sch_generic.h | 1 +
> net/core/dev.c | 24 ------------------------
> net/sched/sch_api.c | 27 +++++++++++++++++++++++++++
> net/sched/sch_tbf.c | 38 +++++++++++++++++++++++++++++++++++++-
> 4 files changed, 65 insertions(+), 25 deletions(-)
>
> diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
> index 2761c90..de6db57 100644
> --- a/include/net/sch_generic.h
> +++ b/include/net/sch_generic.h
> @@ -372,6 +372,7 @@ extern struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
> struct Qdisc_ops *ops, u32 parentid);
> extern void __qdisc_calculate_pkt_len(struct sk_buff *skb,
> const struct qdisc_size_table *stab);
> +extern void qdisc_pkt_len_init(struct sk_buff *skb);
> extern void tcf_destroy(struct tcf_proto *tp);
> extern void tcf_destroy_chain(struct tcf_proto **fl);
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index f444736..8f86b1c 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -2680,30 +2680,6 @@ out:
> return rc;
> }
>
> -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) {
> - unsigned int hdr_len;
> -
> - /* 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)))
> - hdr_len += tcp_hdrlen(skb);
> - else
> - hdr_len += sizeof(struct udphdr);
> - qdisc_skb_cb(skb)->pkt_len += (shinfo->gso_segs - 1) * hdr_len;
> - }
> -}
> -
Please dont move this function, its called in fast path and should be
inlined by compiler
> static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
> struct net_device *dev,
> struct netdev_queue *txq)
> diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
> index fe1ba54..7672259 100644
> --- a/net/sched/sch_api.c
> +++ b/net/sched/sch_api.c
> @@ -29,6 +29,8 @@
> #include <linux/hrtimer.h>
> #include <linux/lockdep.h>
> #include <linux/slab.h>
> +#include <linux/tcp.h>
> +#include <linux/udp.h>
>
> #include <net/net_namespace.h>
> #include <net/sock.h>
> @@ -464,6 +466,31 @@ out:
> }
> EXPORT_SYMBOL(__qdisc_calculate_pkt_len);
>
> +
> void qdisc_warn_nonwc(char *txt, struct Qdisc *qdisc)
> {
> if (!(qdisc->flags & TCQ_F_WARN_NONWC)) {
> diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
> index c8388f3..bfc89be 100644
> --- a/net/sched/sch_tbf.c
> +++ b/net/sched/sch_tbf.c
> @@ -121,7 +121,7 @@ static int tbf_enqueue(struct sk_buff *skb, struct Qdisc *sch)
> struct tbf_sched_data *q = qdisc_priv(sch);
> int ret;
>
> - if (qdisc_pkt_len(skb) > q->max_size)
> + if (qdisc_pkt_len(skb) > q->max_size && !skb_is_gso(skb))
> return qdisc_reshape_fail(skb, sch);
>
> ret = qdisc_enqueue(skb, q->qdisc);
> @@ -147,6 +147,33 @@ static unsigned int tbf_drop(struct Qdisc *sch)
> return len;
> }
>
> +static bool qdisc_gso_segment(struct Qdisc *qdisc, struct sk_buff *skb)
> +{
> + struct sk_buff *segs;
> + struct sk_buff *next_skb;
> + struct sk_buff *prev_skb;
> + int num_skbs = 0;
> +
> + segs = skb_gso_segment(skb, 0);
> + if (IS_ERR(segs) || !segs)
> + return false;
> + __skb_unlink(skb, &qdisc->q);
> + kfree_skb(skb);
> + skb = segs;
> + prev_skb = (struct sk_buff *) &qdisc->q;
> + do {
> + next_skb = skb->next;
> + qdisc_pkt_len_init(skb);
> + qdisc_calculate_pkt_len(skb, qdisc);
You don't need this, packet is non gso, so you only have to
qdisc_skb_cb(skb)->pkt_len = skb->len;
qdisc_calculate_pkt_len();
> + __skb_queue_after(&qdisc->q, prev_skb, skb);
Yes, this might need different strategy for non fifo qdisc, we can
see that later.
> + prev_skb = skb;
> + skb = next_skb;
> + num_skbs++;
> + } while (skb);
> + qdisc_tree_decrease_qlen(qdisc, 1 - num_skbs);
> + return true;
> +}
> +
> static struct sk_buff *tbf_dequeue(struct Qdisc *sch)
> {
> struct tbf_sched_data *q = qdisc_priv(sch);
> @@ -167,6 +194,15 @@ static struct sk_buff *tbf_dequeue(struct Qdisc *sch)
> ptoks = toks + q->ptokens;
> if (ptoks > q->mtu)
> ptoks = q->mtu;
Cache psched_l2t_ns(&q->peak, len) in a variable here to avoid double
call.
> + if (skb_is_gso(skb) &&
> + (s64) psched_l2t_ns(&q->peak, len) > q->mtu &&
> + qdisc_gso_segment(q->qdisc, skb)) {
> + q->qdisc->gso_skb = NULL;
> + skb = q->qdisc->ops->peek(q->qdisc);
> + if (unlikely(!skb))
> + return NULL;
> + len = qdisc_pkt_len(skb);
> + }
> ptoks -= (s64) psched_l2t_ns(&q->peak, len);
> }
> toks += q->tokens;
Thanks !
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