Because we cache the last failed-to-xmit packet, if there are no
packets queued behind that one we may never send it (reproduced here
as TCP stalls, "cured" by an outgoing ping).
Cc: Mark McLoughlin <markmc@xxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
---
drivers/net/virtio_net.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff -r 1d1ff03de434 drivers/net/virtio_net.c
--- a/drivers/net/virtio_net.c Mon May 26 11:03:26 2008 +1000
+++ b/drivers/net/virtio_net.c Mon May 26 16:37:20 2008 +1000
@@ -47,6 +47,9 @@ struct virtnet_info
/* Number of input buffers, and max we've ever had. */
unsigned int num, max;
+ /* For cleaning up after transmission. */
+ struct tasklet_struct tasklet;
+
/* Receive & send queues. */
struct sk_buff_head recv;
struct sk_buff_head send;
@@ -68,8 +71,13 @@ static void skb_xmit_done(struct virtque
/* Suppress further interrupts. */
svq->vq_ops->disable_cb(svq);
+
/* We were waiting for more output buffers. */
netif_wake_queue(vi->dev);
+
+ /* Make sure we re-xmit last_xmit_skb: if there are no more packets
+ * queued, start_xmit won't be called. */
+ tasklet_schedule(&vi->tasklet);
}
static void receive_skb(struct net_device *dev, struct sk_buff *skb,
@@ -278,6 +286,18 @@ static int xmit_skb(struct virtnet_info
return vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);
}
+static void xmit_tasklet(unsigned long data)
+{
+ struct virtnet_info *vi = (void *)data;
+
+ netif_tx_lock_bh(vi->dev);
+ if (vi->last_xmit_skb && xmit_skb(vi, vi->last_xmit_skb) == 0) {
+ vi->svq->vq_ops->kick(vi->svq);
+ vi->last_xmit_skb = NULL;
+ }
+ netif_tx_unlock_bh(vi->dev);
+}
+
static int start_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct virtnet_info *vi = netdev_priv(dev);
@@ -432,6 +452,8 @@ static int virtnet_probe(struct virtio_d
skb_queue_head_init(&vi->recv);
skb_queue_head_init(&vi->send);
+ tasklet_init(&vi->tasklet, xmit_tasklet, (unsigned long)vi);
+
err = register_netdev(dev);
if (err) {
pr_debug("virtio_net: registering device failed\n");
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