netdev - [RFC PATCH 09/17] net: sched: check for frozen queue before skb_bad

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Message-ID: <20171113201035.6245.29801.stgit@john-Precision-Tower-5810>
Date:   Mon, 13 Nov 2017 12:10:35 -0800
From:   John Fastabend <john.fastabend@...il.com>
To:     willemdebruijn.kernel@...il.com, daniel@...earbox.net,
        eric.dumazet@...il.com
Cc:     make0818@...il.com, netdev@...r.kernel.org, jiri@...nulli.us,
        xiyou.wangcong@...il.com
Subject: [RFC PATCH 09/17] 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>
---
 0 files changed

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 92570d4..84c4ea1 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))