Example #1
0
/*
 * NOTE: Called under dev->queue_lock with locally disabled BH.
 *
 * __LINK_STATE_QDISC_RUNNING guarantees only one CPU can process this
 * device at a time. dev->queue_lock serializes queue accesses for
 * this device AND dev->qdisc pointer itself.
 *
 *  netif_tx_lock serializes accesses to device driver.
 *
 *  dev->queue_lock and netif_tx_lock are mutually exclusive,
 *  if one is grabbed, another must be free.
 *
 * Note, that this procedure can be called by a watchdog timer
 *
 * Returns to the caller:
 *				0  - queue is empty or throttled.
 *				>0 - queue is not empty.
 *
 */
static inline int qdisc_restart(struct net_device *dev)
{
	struct Qdisc *q = dev->qdisc;
	struct sk_buff *skb;
	unsigned lockless;
	int ret;

	/* Dequeue packet */
	if (unlikely((skb = dev_dequeue_skb(dev, q)) == NULL))
		return 0;

	/*
	 * When the driver has LLTX set, it does its own locking in
	 * start_xmit. These checks are worth it because even uncongested
	 * locks can be quite expensive. The driver can do a trylock, as
	 * is being done here; in case of lock contention it should return
	 * NETDEV_TX_LOCKED and the packet will be requeued.
	 */
	lockless = (dev->features & NETIF_F_LLTX);

	if (!lockless && !netif_tx_trylock(dev)) {
		/* Another CPU grabbed the driver tx lock */
		return handle_dev_cpu_collision(skb, dev, q);
	}

	/* And release queue */
	spin_unlock(&dev->queue_lock);

	ret = dev_hard_start_xmit(skb, dev);

	if (!lockless)
		netif_tx_unlock(dev);

	spin_lock(&dev->queue_lock);
	q = dev->qdisc;

	switch (ret) {
	case NETDEV_TX_OK:
		/* Driver sent out skb successfully */
		ret = qdisc_qlen(q);
		break;

	case NETDEV_TX_LOCKED:
		/* Driver try lock failed */
		ret = handle_dev_cpu_collision(skb, dev, q);
		break;

	default:
		/* Driver returned NETDEV_TX_BUSY - requeue skb */
		if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit()))
			printk(KERN_WARNING "BUG %s code %d qlen %d\n",
			       dev->name, ret, q->q.qlen);

		ret = dev_requeue_skb(skb, dev, q);
		break;
	}

	return ret;
}
Example #2
0
static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
{
	int status = NETDEV_TX_BUSY;
	unsigned long tries;
	struct net_device *dev = np->dev;
	struct netpoll_info *npinfo = np->dev->npinfo;

	if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
		__kfree_skb(skb);
		return;
	}

	/* don't get messages out of order, and no recursion */
	if (skb_queue_len(&npinfo->txq) == 0 &&
		    npinfo->poll_owner != smp_processor_id()) {
		unsigned long flags;

		local_irq_save(flags);
		/* try until next clock tick */
		for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
		     tries > 0; --tries) {
			if (netif_tx_trylock(dev)) {
				if (!netif_queue_stopped(dev))
					status = dev->hard_start_xmit(skb, dev);
				netif_tx_unlock(dev);

				if (status == NETDEV_TX_OK)
					break;

			}

			/* tickle device maybe there is some cleanup */
			netpoll_poll(np);

			udelay(USEC_PER_POLL);
		}
		local_irq_restore(flags);
	}

	if (status != NETDEV_TX_OK) {
		skb_queue_tail(&npinfo->txq, skb);
		schedule_delayed_work(&npinfo->tx_work,0);
	}
}
Example #3
0
/* Kick device.

   Returns:  0  - queue is empty or throttled.
	    >0  - queue is not empty.

   NOTE: Called under dev->queue_lock with locally disabled BH.
*/
static inline int qdisc_restart(struct net_device *dev)
{
	struct Qdisc *q = dev->qdisc;
	struct sk_buff *skb;

	/* Dequeue packet */
	if (((skb = dev->gso_skb)) || ((skb = q->dequeue(q)))) {
		unsigned nolock = (dev->features & NETIF_F_LLTX);

		dev->gso_skb = NULL;

		/*
		 * When the driver has LLTX set it does its own locking
		 * in start_xmit. No need to add additional overhead by
		 * locking again. These checks are worth it because
		 * even uncongested locks can be quite expensive.
		 * The driver can do trylock like here too, in case
		 * of lock congestion it should return -1 and the packet
		 * will be requeued.
		 */
		if (!nolock) {
			if (!netif_tx_trylock(dev)) {
			collision:
				/* So, someone grabbed the driver. */

				/* It may be transient configuration error,
				   when hard_start_xmit() recurses. We detect
				   it by checking xmit owner and drop the
				   packet when deadloop is detected.
				*/
				if (dev->xmit_lock_owner == smp_processor_id()) {
					kfree_skb(skb);
					if (net_ratelimit())
						printk(KERN_DEBUG "Dead loop on netdevice %s, fix it urgently!\n", dev->name);
					goto out;
				}
				__get_cpu_var(netdev_rx_stat).cpu_collision++;
				goto requeue;
			}
		}

		{
			/* And release queue */
			spin_unlock(&dev->queue_lock);

			if (!netif_queue_stopped(dev)) {
				int ret;

				ret = dev_hard_start_xmit(skb, dev);
				if (ret == NETDEV_TX_OK) {
					if (!nolock) {
						netif_tx_unlock(dev);
					}
					spin_lock(&dev->queue_lock);
					q = dev->qdisc;
					goto out;
				}
				if (ret == NETDEV_TX_LOCKED && nolock) {
					spin_lock(&dev->queue_lock);
					q = dev->qdisc;
					goto collision;
				}
			}

			/* NETDEV_TX_BUSY - we need to requeue */
			/* Release the driver */
			if (!nolock) {
				netif_tx_unlock(dev);
			}
			spin_lock(&dev->queue_lock);
			q = dev->qdisc;
		}

		/* Device kicked us out :(
		   This is possible in three cases:

		   0. driver is locked
		   1. fastroute is enabled
		   2. device cannot determine busy state
		      before start of transmission (f.e. dialout)
		   3. device is buggy (ppp)
		 */

requeue:
		if (unlikely(q == &noop_qdisc))
			kfree_skb(skb);
		else if (skb->next)
			dev->gso_skb = skb;
		else
			q->ops->requeue(skb, q);
		netif_schedule(dev);
	}
	return 0;

out:
	BUG_ON((int) q->q.qlen < 0);
	return q->q.qlen;
}
Example #4
0
File: ifb.c Project: cilynx/dd-wrt
static void ri_tasklet(unsigned long dev)
{

	struct net_device *_dev = (struct net_device *)dev;
	struct ifb_private *dp = netdev_priv(_dev);
	struct net_device_stats *stats = &dp->stats;
	struct sk_buff *skb;

	dp->st_task_enter++;
	if ((skb = skb_peek(&dp->tq)) == NULL) {
		dp->st_txq_refl_try++;
		if (netif_tx_trylock(_dev)) {
			dp->st_rxq_enter++;
			while ((skb = skb_dequeue(&dp->rq)) != NULL) {
				skb_queue_tail(&dp->tq, skb);
				dp->st_rx2tx_tran++;
			}
			netif_tx_unlock(_dev);
		} else {
			/* reschedule */
			dp->st_rxq_notenter++;
			goto resched;
		}
	}

	while ((skb = skb_dequeue(&dp->tq)) != NULL) {
		u32 from = G_TC_FROM(skb->tc_verd);

		skb->tc_verd = 0;
		skb->tc_verd = SET_TC_NCLS(skb->tc_verd);
		stats->tx_packets++;
		stats->tx_bytes +=skb->len;

		skb->dev = __dev_get_by_index(skb->iif);
		if (!skb->dev) {
			dev_kfree_skb(skb);
			stats->tx_dropped++;
			break;
		}
		skb->iif = _dev->ifindex;

		if (from & AT_EGRESS) {
			dp->st_rx_frm_egr++;
			dev_queue_xmit(skb);
		} else if (from & AT_INGRESS) {
			dp->st_rx_frm_ing++;
			skb_pull(skb, skb->dev->hard_header_len);
			netif_rx(skb);
		} else
			BUG();
	}

	if (netif_tx_trylock(_dev)) {
		dp->st_rxq_check++;
		if ((skb = skb_peek(&dp->rq)) == NULL) {
			dp->tasklet_pending = 0;
			if (netif_queue_stopped(_dev))
				netif_wake_queue(_dev);
		} else {
			dp->st_rxq_rsch++;
			netif_tx_unlock(_dev);
			goto resched;
		}
		netif_tx_unlock(_dev);
	} else {
resched:
		dp->tasklet_pending = 1;
		tasklet_schedule(&dp->ifb_tasklet);
	}

}