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Commit d62f38c2 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'sch_cake-leaf-qdisc-fixes' 



Toke Høiland-Jørgensen says:

====================
sched: Fix qdisc interactions exposed by using sch_cake as a leaf qdisc

This series fixes a couple of issues exposed by running sch_cake as a
leaf qdisc in an HFSC tree, which were discovered and reported by Pete
Heist. The interaction between CAKE's GSO splitting and the parent
qdisc's notion of its own queue length could cause queue stalls. While
investigating the report, I also noticed that several qdiscs would
dereference the skb pointer after dequeue, which is potentially
problematic since the GSO splitting code also frees the original skb.

See the individual patches in the series for details.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 80b3671e 8c6c37fd

net/sched/sch_cake.c

+3 −2
Original line number Diff line number Diff line
@@ -1667,7 +1667,7 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch, 
	if (skb_is_gso(skb) && q->rate_flags & CAKE_FLAG_SPLIT_GSO) {

		struct sk_buff *segs, *nskb;

		netdev_features_t features = netif_skb_features(skb);

		unsigned int slen = 0;

		unsigned int slen = 0, numsegs = 0;



		segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);

		if (IS_ERR_OR_NULL(segs))
@@ -1683,6 +1683,7 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch, 
			flow_queue_add(flow, segs);



			sch->q.qlen++;

			numsegs++;

			slen += segs->len;

			q->buffer_used += segs->truesize;

			b->packets++;
@@ -1696,7 +1697,7 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch, 
		sch->qstats.backlog += slen;

		q->avg_window_bytes += slen;



		qdisc_tree_reduce_backlog(sch, 1, len);

		qdisc_tree_reduce_backlog(sch, 1-numsegs, len-slen);

		consume_skb(skb);

	} else {

		/* not splitting */

net/sched/sch_cbs.c

+2 −1
Original line number Diff line number Diff line
@@ -88,13 +88,14 @@ static int cbs_child_enqueue(struct sk_buff *skb, struct Qdisc *sch, 
			     struct Qdisc *child,

			     struct sk_buff **to_free)

{

	unsigned int len = qdisc_pkt_len(skb);

	int err;



	err = child->ops->enqueue(skb, child, to_free);

	if (err != NET_XMIT_SUCCESS)

		return err;



	qdisc_qstats_backlog_inc(sch, skb);

	sch->qstats.backlog += len;

	sch->q.qlen++;



	return NET_XMIT_SUCCESS;

net/sched/sch_drr.c

+5 −2
Original line number Diff line number Diff line
@@ -350,9 +350,11 @@ static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch, 
static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch,

		       struct sk_buff **to_free)

{

	unsigned int len = qdisc_pkt_len(skb);

	struct drr_sched *q = qdisc_priv(sch);

	struct drr_class *cl;

	int err = 0;

	bool first;



	cl = drr_classify(skb, sch, &err);

	if (cl == NULL) {
@@ -362,6 +364,7 @@ static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch, 
		return err;

	}



	first = !cl->qdisc->q.qlen;

	err = qdisc_enqueue(skb, cl->qdisc, to_free);

	if (unlikely(err != NET_XMIT_SUCCESS)) {

		if (net_xmit_drop_count(err)) {
@@ -371,12 +374,12 @@ static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch, 
		return err;

	}



	if (cl->qdisc->q.qlen == 1) {

	if (first) {

		list_add_tail(&cl->alist, &q->active);

		cl->deficit = cl->quantum;

	}



	qdisc_qstats_backlog_inc(sch, skb);

	sch->qstats.backlog += len;

	sch->q.qlen++;

	return err;

}

net/sched/sch_dsmark.c

+2 −1
Original line number Diff line number Diff line
@@ -199,6 +199,7 @@ static struct tcf_block *dsmark_tcf_block(struct Qdisc *sch, unsigned long cl, 
static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch,

			  struct sk_buff **to_free)

{

	unsigned int len = qdisc_pkt_len(skb);

	struct dsmark_qdisc_data *p = qdisc_priv(sch);

	int err;
@@ -271,7 +272,7 @@ static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch, 
		return err;

	}



	qdisc_qstats_backlog_inc(sch, skb);

	sch->qstats.backlog += len;

	sch->q.qlen++;



	return NET_XMIT_SUCCESS;

net/sched/sch_hfsc.c

+5 −4
Original line number Diff line number Diff line
@@ -1539,8 +1539,10 @@ hfsc_dump_qdisc(struct Qdisc *sch, struct sk_buff *skb) 
static int

hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)

{

	unsigned int len = qdisc_pkt_len(skb);

	struct hfsc_class *cl;

	int uninitialized_var(err);

	bool first;



	cl = hfsc_classify(skb, sch, &err);

	if (cl == NULL) {
@@ -1550,6 +1552,7 @@ hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free) 
		return err;

	}



	first = !cl->qdisc->q.qlen;

	err = qdisc_enqueue(skb, cl->qdisc, to_free);

	if (unlikely(err != NET_XMIT_SUCCESS)) {

		if (net_xmit_drop_count(err)) {
@@ -1559,9 +1562,7 @@ hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free) 
		return err;

	}



	if (cl->qdisc->q.qlen == 1) {

		unsigned int len = qdisc_pkt_len(skb);



	if (first) {

		if (cl->cl_flags & HFSC_RSC)

			init_ed(cl, len);

		if (cl->cl_flags & HFSC_FSC)
@@ -1576,7 +1577,7 @@ hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free) 


	}



	qdisc_qstats_backlog_inc(sch, skb);

	sch->qstats.backlog += len;

	sch->q.qlen++;



	return NET_XMIT_SUCCESS;