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[NET]: qdisc_restart - couple of optimizations.

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Changes :

- netif_queue_stopped need not be called inside qdisc_restart as
  it has been called already in qdisc_run() before the first skb
  is sent, and in __qdisc_run() after each intermediate skb is
  sent (note : we are the only sender, so the queue cannot get
  stopped while the tx lock was got in the ~LLTX case).

- BUG_ON((int) q->q.qlen < 0) was a relic from old times when -1
  meant more packets are available, and __qdisc_run used to loop
  when qdisc_restart() returned -1. During those days, it was
  necessary to make sure that qlen is never less than zero, since
  __qdisc_run would get into an infinite loop if no packets are on
  the queue and this bug in qdisc was there (and worse - no more
  skbs could ever get queue'd as we hold the queue lock too). With
  Herbert's recent change to return values, this check is not
  required.  Hopefully Herbert can validate this change. If at all
  this is required, it should be added to skb_dequeue (in failure
  case), and not to qdisc_qlen.

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Krishna Kumar 2007-06-24 19:57:27 -07:00 committed by David S. Miller
parent 6c1361a6f2
commit e50c41b53d
1 changed files with 1 additions and 4 deletions
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5
net/sched/sch_generic.c
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@ -61,7 +61,6 @@ void qdisc_unlock_tree(struct net_device *dev)
static inline int qdisc_qlen(struct Qdisc *q)
{
BUG_ON((int) q->q.qlen < 0);
return q->q.qlen;
}
@ -167,9 +166,7 @@ static inline int qdisc_restart(struct net_device *dev)
/* And release queue */
spin_unlock(&dev->queue_lock);
ret = NETDEV_TX_BUSY;
if (!netif_queue_stopped(dev))
ret = dev_hard_start_xmit(skb, dev);
ret = dev_hard_start_xmit(skb, dev);
if (!lockless)
netif_tx_unlock(dev);