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Commit 11a3a154 authored by Rusty Russell's avatar Rusty Russell Committed by Jeff Garzik
Browse files

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: default avatarRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
parent 7eb2e251

drivers/net/virtio_net.c

+22 −0
Original line number Diff line number Diff line
@@ -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");