pkt_sched: Check the state of tx_queue in dequeue_skb()
Check in dequeue_skb() the state of tx_queue for requeued skb to save
on locking and re-requeuing, and possibly remove the current check in
qdisc_run(). Based on the idea of Alexander Duyck.
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 1b508bd..5e7e0bd 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -52,11 +52,21 @@
static inline struct sk_buff *dequeue_skb(struct Qdisc *q)
{
- struct sk_buff *skb;
+ struct sk_buff *skb = skb_peek(&q->requeue);
- skb = __skb_dequeue(&q->requeue);
- if (!skb)
+ if (unlikely(skb)) {
+ struct net_device *dev = qdisc_dev(q);
+ struct netdev_queue *txq;
+
+ /* check the reason of requeuing without tx lock first */
+ txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
+ if (!netif_tx_queue_stopped(txq) && !netif_tx_queue_frozen(txq))
+ __skb_unlink(skb, &q->requeue);
+ else
+ skb = NULL;
+ } else {
skb = q->dequeue(q);
+ }
return skb;
}