Commit 77be155c authored by Jarek Poplawski's avatar Jarek Poplawski Committed by David S. Miller
Browse files

pkt_sched: Add peek emulation for non-work-conserving qdiscs. 



This patch adds qdisc_peek_dequeued() wrapper to emulate peek method
with qdisc->dequeue() and storing "peeked" skb in qdisc->gso_skb until
dequeuing. This is mainly for compatibility reasons not to break some
strange configs because peeking is expected for non-work-conserving
parent qdiscs to query work-conserving child qdiscs.

This implementation requires using qdisc_dequeue_peeked() wrapper
instead of directly calling qdisc->dequeue() for all qdiscs ever
querried with qdisc->ops->peek() or qdisc_peek_dequeued().

Signed-off-by: default avatarJarek Poplawski <jarkao2@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 03c05f0d

include/net/sch_generic.h

+23 −0
Original line number Diff line number Diff line
@@ -438,6 +438,29 @@ static inline struct sk_buff *qdisc_peek_head(struct Qdisc *sch) 
	return skb_peek(&sch->q);

}



/* generic pseudo peek method for non-work-conserving qdisc */

static inline struct sk_buff *qdisc_peek_dequeued(struct Qdisc *sch)

{

	/* we can reuse ->gso_skb because peek isn't called for root qdiscs */

	if (!sch->gso_skb)

		sch->gso_skb = sch->dequeue(sch);



	return sch->gso_skb;

}



/* use instead of qdisc->dequeue() for all qdiscs queried with ->peek() */

static inline struct sk_buff *qdisc_dequeue_peeked(struct Qdisc *sch)

{

	struct sk_buff *skb = sch->gso_skb;



	if (skb)

		sch->gso_skb = NULL;

	else

		skb = sch->dequeue(sch);



	return skb;

}



static inline int __qdisc_requeue(struct sk_buff *skb, struct Qdisc *sch,

				  struct sk_buff_head *list)

{

net/sched/sch_atm.c

+2 −2
Original line number Diff line number Diff line
@@ -484,7 +484,7 @@ static void sch_atm_dequeue(unsigned long data) 
			if (!atm_may_send(flow->vcc, skb->truesize))

				break;



			skb = flow->q->dequeue(flow->q);

			skb = qdisc_dequeue_peeked(flow->q);

			if (unlikely(!skb))

				break;
@@ -519,7 +519,7 @@ static struct sk_buff *atm_tc_dequeue(struct Qdisc *sch) 


	pr_debug("atm_tc_dequeue(sch %p,[qdisc %p])\n", sch, p);

	tasklet_schedule(&p->task);

	skb = p->link.q->dequeue(p->link.q);

	skb = qdisc_dequeue_peeked(p->link.q);

	if (skb)

		sch->q.qlen--;

	return skb;

net/sched/sch_cbq.c

+1 −0
Original line number Diff line number Diff line
@@ -2066,6 +2066,7 @@ static struct Qdisc_ops cbq_qdisc_ops __read_mostly = { 
	.priv_size	=	sizeof(struct cbq_sched_data),

	.enqueue	=	cbq_enqueue,

	.dequeue	=	cbq_dequeue,

	.peek		=	qdisc_peek_dequeued,

	.requeue	=	cbq_requeue,

	.drop		=	cbq_drop,

	.init		=	cbq_init,

net/sched/sch_hfsc.c

+2 −1
Original line number Diff line number Diff line
@@ -1634,7 +1634,7 @@ hfsc_dequeue(struct Qdisc *sch) 
		}

	}



	skb = cl->qdisc->dequeue(cl->qdisc);

	skb = qdisc_dequeue_peeked(cl->qdisc);

	if (skb == NULL) {

		if (net_ratelimit())

			printk("HFSC: Non-work-conserving qdisc ?\n");
@@ -1727,6 +1727,7 @@ static struct Qdisc_ops hfsc_qdisc_ops __read_mostly = { 
	.dump		= hfsc_dump_qdisc,

	.enqueue	= hfsc_enqueue,

	.dequeue	= hfsc_dequeue,

	.peek		= qdisc_peek_dequeued,

	.requeue	= hfsc_requeue,

	.drop		= hfsc_drop,

	.cl_ops		= &hfsc_class_ops,

net/sched/sch_htb.c

+1 −0
Original line number Diff line number Diff line
@@ -1565,6 +1565,7 @@ static struct Qdisc_ops htb_qdisc_ops __read_mostly = { 
	.priv_size	=	sizeof(struct htb_sched),

	.enqueue	=	htb_enqueue,

	.dequeue	=	htb_dequeue,

	.peek		=	qdisc_peek_dequeued,

	.requeue	=	htb_requeue,

	.drop		=	htb_drop,

	.init		=	htb_init,

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