From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.toke.dk (mail.toke.dk [52.28.52.200]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 3D6383CBCA for ; Mon, 7 Jan 2019 14:48:14 -0500 (EST) From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=toke.dk; s=20161023; t=1546890493; bh=q4GL5uJNi3y/NPyBW0a5EKuj9E4NXFNR7mgKTHWcbMo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CtEeL6nJQTzYZyHTn7mnIec201hoq7bd0yj0fddLxUpV38o/K0Yyju84otCq6MM7N mTIlYaVQW3d+Ar4JkD0gnX8RJBbPVKUv5DEMfVvVjGsD1vpVaqRduQZxe/uZoMe18U t0kDQZBtI/hhUjl7eHgskJcsGeO7XHY84ahXasI6sOMG1bEOm9Vee+R37RjcktAiz6 8Q6ZFvxPKJbTBBWMwQW+aEnZNz1AKFN5zCOOo0rHyJQSAV2z/v2thJDfjv7PrCMlll EcZAskmxJoV65VbU1lCf3Wb1mqs3Cp93nuci0TAwmzrrWKD3MmeHWeiBdpgnvctsME 0tHe4Iy4cxqHw== To: netdev@vger.kernel.org Cc: cake@lists.bufferbloat.net, =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Pete Heist Date: Mon, 7 Jan 2019 20:47:31 +0100 Message-Id: <20190107194733.31138-3-toke@toke.dk> In-Reply-To: <20190107194733.31138-1-toke@toke.dk> References: <20190107194733.31138-1-toke@toke.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: [Cake] [PATCH 2/4] sched: Fix detection of empty queues in child qdiscs X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 07 Jan 2019 19:48:14 -0000 From: Toke Høiland-Jørgensen 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 --- net/sched/sch_drr.c | 4 +++- net/sched/sch_hfsc.c | 4 +++- net/sched/sch_qfq.c | 4 +++- 3 files changed, 9 insertions(+), 3 deletions(-) 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; } diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c index 6bb8f73a8473..24cc220a3218 100644 --- a/net/sched/sch_hfsc.c +++ b/net/sched/sch_hfsc.c @@ -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) diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c index 8d5e55d5bed2..29f5c4a24688 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -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) -- 2.20.1