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authorJarek Poplawski <jarkao2@gmail.com>2008-09-22 22:16:23 -0700
committerDavid S. Miller <davem@davemloft.net>2008-09-22 22:16:23 -0700
commitebf059821ed8a36acd706484b719d14d212ada32 (patch)
tree44b2ee2887113ea5d90b35f4c4ae1a376f38e94f /net/sched
parentf0876520b0b721bedafd9cec3b1b0624ae566eee (diff)
downloadlinux-2.6.38-lt-ux500-ebf059821ed8a36acd706484b719d14d212ada32.tar.gz
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>
Diffstat (limited to 'net/sched')
-rw-r--r--net/sched/sch_generic.c18
1 files changed, 14 insertions, 4 deletions
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 1b508bd1c06..5e7e0bd38fe 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -52,11 +52,21 @@ static inline int dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
static inline struct sk_buff *dequeue_skb(struct Qdisc *q)
{
- struct sk_buff *skb;
-
- skb = __skb_dequeue(&q->requeue);
- if (!skb)
+ struct sk_buff *skb = skb_peek(&q->requeue);
+
+ 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;
}