1 files changed, 77 insertions, 14 deletions

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index f926b5a..4452306 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -44,9 +44,16 @@ struct virtnet_info
 	/* The skb we couldn't send because buffers were full. */
 	struct sk_buff *last_xmit_skb;
 
+	/* If we need to free in a timer, this is it. */
+	struct timer_list xmit_free_timer;
+
 	/* Number of input buffers, and max we've ever had. */
 	unsigned int num, max;
 
+	/* For cleaning up after transmission. */
+	struct tasklet_struct tasklet;
+	bool free_in_tasklet;
+
 	/* Receive & send queues. */
 	struct sk_buff_head recv;
 	struct sk_buff_head send;
@@ -68,8 +75,13 @@ static void skb_xmit_done(struct virtqueue *svq)
 
 	/* Suppress further interrupts. */
 	svq->vq_ops->disable_cb(svq);
-	/* We were waiting for more output buffers. */
+
+	/* We were probably 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,
@@ -86,9 +98,7 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb,
 	BUG_ON(len > MAX_PACKET_LEN);
 
 	skb_trim(skb, len);
-	skb->protocol = eth_type_trans(skb, dev);
-	pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
-		 ntohs(skb->protocol), skb->len, skb->pkt_type);
+
 	dev->stats.rx_bytes += skb->len;
 	dev->stats.rx_packets++;
 
@@ -98,6 +108,10 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb,
 			goto frame_err;
 	}
 
+	skb->protocol = eth_type_trans(skb, dev);
+	pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
+		 ntohs(skb->protocol), skb->len, skb->pkt_type);
+
 	if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
 		pr_debug("GSO!\n");
 		switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
@@ -230,9 +244,25 @@ static void free_old_xmit_skbs(struct virtnet_info *vi)
 	}
 }
 
+/* If the virtio transport doesn't always notify us when all in-flight packets
+ * are consumed, we fall back to using this function on a timer to free them. */
+static void xmit_free(unsigned long data)
+{
+	struct virtnet_info *vi = (void *)data;
+
+	netif_tx_lock(vi->dev);
+
+	free_old_xmit_skbs(vi);
+
+	if (!skb_queue_empty(&vi->send))
+		mod_timer(&vi->xmit_free_timer, jiffies + (HZ/10));
+
+	netif_tx_unlock(vi->dev);
+}
+
 static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb)
 {
-	int num;
+	int num, err;
 	struct scatterlist sg[2+MAX_SKB_FRAGS];
 	struct virtio_net_hdr *hdr;
 	const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
@@ -275,7 +305,25 @@ static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb)
 	vnet_hdr_to_sg(sg, skb);
 	num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
 
-	return vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);
+	err = vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);
+	if (!err && !vi->free_in_tasklet)
+		mod_timer(&vi->xmit_free_timer, jiffies + (HZ/10));
+
+	return err;
+}
+
+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;
+	}
+	if (vi->free_in_tasklet)
+		free_old_xmit_skbs(vi);
+	netif_tx_unlock_bh(vi->dev);
 }
 
 static int start_xmit(struct sk_buff *skb, struct net_device *dev)
@@ -287,21 +335,25 @@ again:
 	free_old_xmit_skbs(vi);
 
 	/* If we has a buffer left over from last time, send it now. */
-	if (vi->last_xmit_skb) {
+	if (unlikely(vi->last_xmit_skb)) {
 		if (xmit_skb(vi, vi->last_xmit_skb) != 0) {
 			/* Drop this skb: we only queue one. */
 			vi->dev->stats.tx_dropped++;
 			kfree_skb(skb);
+			skb = NULL;
 			goto stop_queue;
 		}
 		vi->last_xmit_skb = NULL;
 	}
 
 	/* Put new one in send queue and do transmit */
-	__skb_queue_head(&vi->send, skb);
-	if (xmit_skb(vi, skb) != 0) {
-		vi->last_xmit_skb = skb;
-		goto stop_queue;
+	if (likely(skb)) {
+		__skb_queue_head(&vi->send, skb);
+		if (xmit_skb(vi, skb) != 0) {
+			vi->last_xmit_skb = skb;
+			skb = NULL;
+			goto stop_queue;
+		}
 	}
 done:
 	vi->svq->vq_ops->kick(vi->svq);
@@ -411,6 +463,10 @@ static int virtnet_probe(struct virtio_device *vdev)
 	vi->vdev = vdev;
 	vdev->priv = vi;
 
+	/* If they give us a callback when all buffers are done, we don't need
+	 * the timer. */
+	vi->free_in_tasklet = virtio_has_feature(vdev,VIRTIO_F_NOTIFY_ON_EMPTY);
+
 	/* We expect two virtqueues, receive then send. */
 	vi->rvq = vdev->config->find_vq(vdev, 0, skb_recv_done);
 	if (IS_ERR(vi->rvq)) {
@@ -428,6 +484,11 @@ 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);
+
+	if (!vi->free_in_tasklet)
+		setup_timer(&vi->xmit_free_timer, xmit_free, (unsigned long)vi);
+
 	err = register_netdev(dev);
 	if (err) {
 		pr_debug("virtio_net: registering device failed\n");
@@ -465,13 +526,15 @@ static void virtnet_remove(struct virtio_device *vdev)
 	/* Stop all the virtqueues. */
 	vdev->config->reset(vdev);
 
+	if (!vi->free_in_tasklet)
+		del_timer_sync(&vi->xmit_free_timer);
+
 	/* Free our skbs in send and recv queues, if any. */
 	while ((skb = __skb_dequeue(&vi->recv)) != NULL) {
 		kfree_skb(skb);
 		vi->num--;
 	}
-	while ((skb = __skb_dequeue(&vi->send)) != NULL)
-		kfree_skb(skb);
+	__skb_queue_purge(&vi->send);
 
 	BUG_ON(vi->num != 0);
 
@@ -489,7 +552,7 @@ static struct virtio_device_id id_table[] = {
 static unsigned int features[] = {
 	VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GSO, VIRTIO_NET_F_MAC,
 	VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6,
-	VIRTIO_NET_F_HOST_ECN,
+	VIRTIO_NET_F_HOST_ECN, VIRTIO_F_NOTIFY_ON_EMPTY,
 };
 
 static struct virtio_driver virtio_net = {