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virtio: fix delayed xmit of packet and freeing of old packets. 

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@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
This commit is contained in:
Rusty Russell 2008-05-26 17:48:13 +10:00 committed by Jeff Garzik
parent 7eb2e25112
commit 11a3a1546d
1 changed files with 22 additions and 0 deletions
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22
drivers/net/virtio_net.c
View File

@ -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 virtqueue *svq)
/* 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 *vi, struct sk_buff *skb)
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_device *vdev)
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");