Commit 65c7973f authored by Jesse Brandeburg's avatar Jesse Brandeburg Committed by Auke Kok
Browse files

e1000: Maybe stop TX if not enough free descriptors 



Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarJesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: default avatarAuke Kok <auke-jan.h.kok@intel.com>
parent 249d71d6

drivers/net/e1000/e1000_main.c

+42 −10
Original line number Diff line number Diff line
@@ -2899,6 +2899,35 @@ e1000_transfer_dhcp_info(struct e1000_adapter *adapter, struct sk_buff *skb) 
	return 0;

}



static int __e1000_maybe_stop_tx(struct net_device *netdev, int size)

{

	struct e1000_adapter *adapter = netdev_priv(netdev);

	struct e1000_tx_ring *tx_ring = adapter->tx_ring;



	netif_stop_queue(netdev);

	/* Herbert's original patch had:

	 *  smp_mb__after_netif_stop_queue();

	 * but since that doesn't exist yet, just open code it. */

	smp_mb();



	/* We need to check again in a case another CPU has just

	 * made room available. */

	if (likely(E1000_DESC_UNUSED(tx_ring) < size))

		return -EBUSY;



	/* A reprieve! */

	netif_start_queue(netdev);

	return 0;

}



static int e1000_maybe_stop_tx(struct net_device *netdev,

                               struct e1000_tx_ring *tx_ring, int size)

{

	if (likely(E1000_DESC_UNUSED(tx_ring) >= size))

		return 0;

	return __e1000_maybe_stop_tx(netdev, size);

}



#define TXD_USE_COUNT(S, X) (((S) >> (X)) + 1 )

static int

e1000_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
@@ -2917,6 +2946,10 @@ e1000_xmit_frame(struct sk_buff *skb, struct net_device *netdev) 
	unsigned int f;

	len -= skb->data_len;



	/* This goes back to the question of how to logically map a tx queue

	 * to a flow.  Right now, performance is impacted slightly negatively

	 * if using multiple tx queues.  If the stack breaks away from a

	 * single qdisc implementation, we can look at this again. */

	tx_ring = adapter->tx_ring;



	if (unlikely(skb->len <= 0)) {
@@ -3012,8 +3045,7 @@ e1000_xmit_frame(struct sk_buff *skb, struct net_device *netdev) 


	/* need: count + 2 desc gap to keep tail from touching

	 * head, otherwise try next time */

	if (unlikely(E1000_DESC_UNUSED(tx_ring) < count + 2)) {

		netif_stop_queue(netdev);

	if (unlikely(e1000_maybe_stop_tx(netdev, tx_ring, count + 2))) {

		spin_unlock_irqrestore(&tx_ring->tx_lock, flags);

		return NETDEV_TX_BUSY;

	}
@@ -3060,8 +3092,7 @@ e1000_xmit_frame(struct sk_buff *skb, struct net_device *netdev) 
	netdev->trans_start = jiffies;



	/* Make sure there is space in the ring for the next send. */

	if (unlikely(E1000_DESC_UNUSED(tx_ring) < MAX_SKB_FRAGS + 2))

		netif_stop_queue(netdev);

	e1000_maybe_stop_tx(netdev, tx_ring, MAX_SKB_FRAGS + 2);



	spin_unlock_irqrestore(&tx_ring->tx_lock, flags);

	return NETDEV_TX_OK;
@@ -3556,13 +3587,14 @@ e1000_clean_tx_irq(struct e1000_adapter *adapter, 
	tx_ring->next_to_clean = i;



#define TX_WAKE_THRESHOLD 32

	if (unlikely(cleaned && netif_queue_stopped(netdev) &&

	             netif_carrier_ok(netdev))) {

		spin_lock(&tx_ring->tx_lock);

		if (netif_queue_stopped(netdev) &&

		    (E1000_DESC_UNUSED(tx_ring) >= TX_WAKE_THRESHOLD))

	if (unlikely(cleaned && netif_carrier_ok(netdev) &&

		     E1000_DESC_UNUSED(tx_ring) >= TX_WAKE_THRESHOLD)) {

		/* Make sure that anybody stopping the queue after this

		 * sees the new next_to_clean.

		 */

		smp_mb();

		if (netif_queue_stopped(netdev))

			netif_wake_queue(netdev);

		spin_unlock(&tx_ring->tx_lock);

	}



	if (adapter->detect_tx_hung) {