[Xen-devel] [PATCH v2 net-next 4/7] xen-netback: immediately wake tx queue when guest rx queue has space

[Paul Durrant <paul.durrant@xxxxxxxxxx>]

From: David Vrabel <david.vrabel@xxxxxxxxxx>

When an skb is removed from the guest rx queue, immediately wake the
tx queue, instead of after processing them.

Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
[re-based]
Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 drivers/net/xen-netback/rx.c | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/drivers/net/xen-netback/rx.c b/drivers/net/xen-netback/rx.c
index b0ce4c6..9548709 100644
--- a/drivers/net/xen-netback/rx.c
+++ b/drivers/net/xen-netback/rx.c
@@ -92,27 +92,21 @@ static struct sk_buff *xenvif_rx_dequeue(struct 
xenvif_queue *queue)
        spin_lock_irq(&queue->rx_queue.lock);
 
        skb = __skb_dequeue(&queue->rx_queue);
-       if (skb)
+       if (skb) {
                queue->rx_queue_len -= skb->len;
+               if (queue->rx_queue_len < queue->rx_queue_max) {
+                       struct netdev_queue *txq;
+
+                       txq = netdev_get_tx_queue(queue->vif->dev, queue->id);
+                       netif_tx_wake_queue(txq);
+               }
+       }
 
        spin_unlock_irq(&queue->rx_queue.lock);
 
        return skb;
 }
 
-static void xenvif_rx_queue_maybe_wake(struct xenvif_queue *queue)
-{
-       spin_lock_irq(&queue->rx_queue.lock);
-
-       if (queue->rx_queue_len < queue->rx_queue_max) {
-               struct net_device *dev = queue->vif->dev;
-
-               netif_tx_wake_queue(netdev_get_tx_queue(dev, queue->id));
-       }
-
-       spin_unlock_irq(&queue->rx_queue.lock);
-}
-
 static void xenvif_rx_queue_purge(struct xenvif_queue *queue)
 {
        struct sk_buff *skb;
@@ -585,8 +579,6 @@ int xenvif_kthread_guest_rx(void *data)
                 */
                xenvif_rx_queue_drop_expired(queue);
 
-               xenvif_rx_queue_maybe_wake(queue);
-
                cond_resched();
        }
 
-- 
2.1.4


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