From 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Date: Wed, 9 Jan 2019 17:09:43 +0100 Subject: sched: Fix detection of empty queues in child qdiscs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: David S. Miller --- net/sched/sch_drr.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'net/sched/sch_drr.c') diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c index feaf47178653..09b800991065 100644 --- a/net/sched/sch_drr.c +++ b/net/sched/sch_drr.c @@ -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; } -- cgit v1.2.3