virtio: free transmit skbs when notified, not on next xmit.
This fixes a potential dangling xmit problem.
We also suppress refill interrupts until we need them.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index bd4d26a..a61c176 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -56,11 +56,13 @@
sg_init_one(sg, skb_vnet_hdr(skb), sizeof(struct virtio_net_hdr));
}
-static void skb_xmit_done(struct virtqueue *rvq)
+static void skb_xmit_done(struct virtqueue *svq)
{
- struct virtnet_info *vi = rvq->vdev->priv;
+ struct virtnet_info *vi = svq->vdev->priv;
- /* In case we were waiting for output buffers. */
+ /* Suppress further interrupts. */
+ svq->vq_ops->disable_cb(svq);
+ /* We were waiting for more output buffers. */
netif_wake_queue(vi->dev);
}
@@ -232,8 +234,6 @@
pr_debug("%s: xmit %p %s\n", dev->name, skb, print_mac(mac, dest));
- free_old_xmit_skbs(vi);
-
/* Encode metadata header at front. */
hdr = skb_vnet_hdr(skb);
if (skb->ip_summed == CHECKSUM_PARTIAL) {
@@ -266,11 +266,24 @@
vnet_hdr_to_sg(sg, skb);
num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
__skb_queue_head(&vi->send, skb);
+
+again:
+ /* Free up any pending old buffers before queueing new ones. */
+ free_old_xmit_skbs(vi);
err = vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);
if (err) {
pr_debug("%s: virtio not prepared to send\n", dev->name);
- skb_unlink(skb, &vi->send);
netif_stop_queue(dev);
+
+ /* Activate callback for using skbs: if this fails it
+ * means some were used in the meantime. */
+ if (unlikely(!vi->svq->vq_ops->enable_cb(vi->svq))) {
+ printk("Unlikely: restart svq failed\n");
+ netif_start_queue(dev);
+ goto again;
+ }
+ __skb_unlink(skb, &vi->send);
+
return NETDEV_TX_BUSY;
}
vi->svq->vq_ops->kick(vi->svq);