sched: Fix detection of empty queues in child qdiscs
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>
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@ -354,6 +354,7 @@ static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch,
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struct drr_sched *q = qdisc_priv(sch);
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struct drr_class *cl;
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int err = 0;
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bool first;
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cl = drr_classify(skb, sch, &err);
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if (cl == NULL) {
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@ -363,6 +364,7 @@ static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch,
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return err;
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}
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first = !cl->qdisc->q.qlen;
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err = qdisc_enqueue(skb, cl->qdisc, to_free);
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if (unlikely(err != NET_XMIT_SUCCESS)) {
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if (net_xmit_drop_count(err)) {
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@ -372,7 +374,7 @@ static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch,
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return err;
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}
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if (cl->qdisc->q.qlen == 1) {
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if (first) {
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list_add_tail(&cl->alist, &q->active);
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cl->deficit = cl->quantum;
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}
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@ -1542,6 +1542,7 @@ hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
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unsigned int len = qdisc_pkt_len(skb);
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struct hfsc_class *cl;
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int uninitialized_var(err);
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bool first;
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cl = hfsc_classify(skb, sch, &err);
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if (cl == NULL) {
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@ -1551,6 +1552,7 @@ hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
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return err;
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}
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first = !cl->qdisc->q.qlen;
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err = qdisc_enqueue(skb, cl->qdisc, to_free);
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if (unlikely(err != NET_XMIT_SUCCESS)) {
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if (net_xmit_drop_count(err)) {
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@ -1560,7 +1562,7 @@ hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
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return err;
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}
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if (cl->qdisc->q.qlen == 1) {
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if (first) {
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if (cl->cl_flags & HFSC_RSC)
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init_ed(cl, len);
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if (cl->cl_flags & HFSC_FSC)
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@ -1215,6 +1215,7 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
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struct qfq_class *cl;
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struct qfq_aggregate *agg;
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int err = 0;
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bool first;
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cl = qfq_classify(skb, sch, &err);
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if (cl == NULL) {
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@ -1236,6 +1237,7 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
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}
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gso_segs = skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 1;
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first = !cl->qdisc->q.qlen;
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err = qdisc_enqueue(skb, cl->qdisc, to_free);
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if (unlikely(err != NET_XMIT_SUCCESS)) {
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pr_debug("qfq_enqueue: enqueue failed %d\n", err);
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@ -1253,7 +1255,7 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
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agg = cl->agg;
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/* if the queue was not empty, then done here */
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if (cl->qdisc->q.qlen != 1) {
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if (!first) {
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if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) &&
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list_first_entry(&agg->active, struct qfq_class, alist)
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== cl && cl->deficit < len)
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