netdev - [net-next PATCH 09/14] net: sched: check for frozen queue before skb_bad

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Date:   Thu, 07 Dec 2017 09:56:42 -0800
From:   John Fastabend <john.fastabend@...il.com>
To:     willemdebruijn.kernel@...il.com, daniel@...earbox.net,
        eric.dumazet@...il.com, davem@...emloft.net
Cc:     netdev@...r.kernel.org, jiri@...nulli.us, xiyou.wangcong@...il.com
Subject: [net-next PATCH 09/14] net: sched: check for frozen queue before
 skb_bad_txq check

I can not think of any reason to pull the bad txq skb off the qdisc if
the txq we plan to send this on is still frozen. So check for frozen
queue first and abort before dequeuing either skb_bad_txq skb or
normal qdisc dequeue() skb.

Signed-off-by: John Fastabend <john.fastabend@...il.com>
---
 net/sched/sch_generic.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 84cef05..5ff93c2 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -204,7 +204,7 @@ static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
 				   int *packets)
 {
 	const struct netdev_queue *txq = q->dev_queue;
-	struct sk_buff *skb;
+	struct sk_buff *skb = NULL;
 
 	*packets = 1;
 	if (unlikely(!skb_queue_empty(&q->gso_skb))) {
@@ -248,12 +248,15 @@ static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
 	}
 validate:
 	*validate = true;
+
+	if ((q->flags & TCQ_F_ONETXQUEUE) &&
+	    netif_xmit_frozen_or_stopped(txq))
+		return skb;
+
 	skb = qdisc_dequeue_skb_bad_txq(q);
 	if (unlikely(skb))
 		goto bulk;
-	if (!(q->flags & TCQ_F_ONETXQUEUE) ||
-	    !netif_xmit_frozen_or_stopped(txq))
-		skb = q->dequeue(q);
+	skb = q->dequeue(q);
 	if (skb) {
 bulk:
 		if (qdisc_may_bulk(q))