[PATCH 6.1 156/303] net/sched: taprio: avoid calling child->ops->dequeue(child) twice

6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Vladimir Oltean <[email protected]>

[ Upstream commit 4c22942734f0814d3c928c25a80f48df0a6ce45e ]

Simplify taprio_dequeue_from_txq() by noticing that we can goto one call
earlier than the previous skb_found label. This is possible because
we've unified the treatment of the child->ops->dequeue(child) return
call, we always try other TXQs now, instead of abandoning the root
dequeue completely if we failed in the peek() case.

Signed-off-by: Vladimir Oltean <[email protected]>
Reviewed-by: Kurt Kanzenbach <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Stable-dep-of: e056e1dfcddc ("net/sched: sch_taprio: Replace direct dequeue call with peek and qdisc_dequeue_peeked")
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 net/sched/sch_taprio.c |   10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -567,12 +567,8 @@ static struct sk_buff *taprio_dequeue_fr
 	if (unlikely(!child))
 		return NULL;
 
-	if (TXTIME_ASSIST_IS_ENABLED(q->flags)) {
-		skb = child->ops->dequeue(child);
-		if (!skb)
-			return NULL;
-		goto skb_found;
-	}
+	if (TXTIME_ASSIST_IS_ENABLED(q->flags))
+		goto skip_peek_checks;
 
 	skb = child->ops->peek(child);
 	if (!skb)
@@ -599,11 +595,11 @@ static struct sk_buff *taprio_dequeue_fr
 	    atomic_sub_return(len, &entry->budget) < 0)
 		return NULL;
 
+skip_peek_checks:
 	skb = child->ops->dequeue(child);
 	if (unlikely(!skb))
 		return NULL;
 
-skb_found:
 	qdisc_bstats_update(sch, skb);
 	qdisc_qstats_backlog_dec(sch, skb);
 	sch->q.qlen--;