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sched: Fix detection of empty queues in child qdiscs

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Several qdiscs check on enqueue whether the packet was enqueued to a class
with an empty queue, in which case the class is activated. This is done by
checking if the qlen is exactly 1 after enqueue. However, if GSO splitting
is enabled in the child qdisc, a single packet can result in a qlen longer
than 1. This means the activation check fails, leading to a stalled queue.

Fix this by checking if the queue is empty *before* enqueue, and running
the activation logic if this was the case.

Reported-by: Pete Heist <pete@heistp.net>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Toke Høiland-Jørgensen 2019-01-09 17:09:43 +01:00 committed by David S. Miller
parent f6bab19931
commit 37d9cf1a3c
3 changed files with 9 additions and 3 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

4
net/sched/sch_drr.c
View file

@ -354,6 +354,7 @@ static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch,
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) {
@ -363,6 +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)) {
@ -372,7 +374,7 @@ 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;
}

4
net/sched/sch_hfsc.c
View file

@ -1542,6 +1542,7 @@ 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) {
@ -1551,6 +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)) {
@ -1560,7 +1562,7 @@ hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
return err;
}
if (cl->qdisc->q.qlen == 1) {
if (first) {
if (cl->cl_flags & HFSC_RSC)
init_ed(cl, len);
if (cl->cl_flags & HFSC_FSC)

4
net/sched/sch_qfq.c
View file

@ -1215,6 +1215,7 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct qfq_class *cl;
struct qfq_aggregate *agg;
int err = 0;
bool first;
cl = qfq_classify(skb, sch, &err);
if (cl == NULL) {
@ -1236,6 +1237,7 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
}
gso_segs = skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 1;
first = !cl->qdisc->q.qlen;
err = qdisc_enqueue(skb, cl->qdisc, to_free);
if (unlikely(err != NET_XMIT_SUCCESS)) {
pr_debug("qfq_enqueue: enqueue failed %d\n", err);
@ -1253,7 +1255,7 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
agg = cl->agg;
/* if the queue was not empty, then done here */
if (cl->qdisc->q.qlen != 1) {
if (!first) {
if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) &&
list_first_entry(&agg->active, struct qfq_class, alist)
== cl && cl->deficit < len)