1 files changed, 77 insertions, 14 deletions

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index f926b5ab3d09..4452306d5328 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 = {