Commit 9ed4cb07 authored by Rusty Russell's avatar Rusty Russell
Browse files

virtio_net: don't rely on virtqueue_add_buf() returning capacity. 



Now we can easily use vq->num_free to determine if there are descriptors
left in the queue, we're about to change virtqueue_add_buf() to return 0
on success.  The virtio_net driver is the only one which actually uses
the return value, so change that.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 7bedc7dc

drivers/net/virtio_net.c

+13 −20
Original line number Diff line number Diff line
@@ -471,10 +471,11 @@ static bool try_fill_recv(struct virtnet_info *vi, gfp_t gfp) 
			err = add_recvbuf_small(vi, gfp);



		oom = err == -ENOMEM;

		if (err < 0)

		if (err)

			break;

		++vi->num;

	} while (err > 0);

	} while (vi->rvq->num_free);



	if (unlikely(vi->num > vi->max))

		vi->max = vi->num;

	virtqueue_kick(vi->rvq);
@@ -625,27 +626,20 @@ static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb) 
static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)

{

	struct virtnet_info *vi = netdev_priv(dev);

	int capacity;

	int err;



	/* Free up any pending old buffers before queueing new ones. */

	free_old_xmit_skbs(vi);



	/* Try to transmit */

	capacity = xmit_skb(vi, skb);

	err = xmit_skb(vi, skb);



	/* This can happen with OOM and indirect buffers. */

	if (unlikely(capacity < 0)) {

		if (likely(capacity == -ENOMEM)) {

			if (net_ratelimit())

				dev_warn(&dev->dev,

					 "TX queue failure: out of memory\n");

		} else {

	/* This should not happen! */

	if (unlikely(err < 0)) {

		dev->stats.tx_fifo_errors++;

		if (net_ratelimit())

			dev_warn(&dev->dev,

					 "Unexpected TX queue failure: %d\n",

					 capacity);

		}

				 "Unexpected TX queue failure: %d\n", err);

		dev->stats.tx_dropped++;

		kfree_skb(skb);

		return NETDEV_TX_OK;
@@ -658,13 +652,12 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) 


	/* Apparently nice girls don't return TX_BUSY; stop the queue

	 * before it gets out of hand.  Naturally, this wastes entries. */

	if (capacity < 2+MAX_SKB_FRAGS) {

	if (vi->svq->num_free < 2+MAX_SKB_FRAGS) {

		netif_stop_queue(dev);

		if (unlikely(!virtqueue_enable_cb_delayed(vi->svq))) {

			/* More just got used, free them then recheck. */

			free_old_xmit_skbs(vi);

			capacity = vi->svq->num_free;

			if (capacity >= 2+MAX_SKB_FRAGS) {

			if (vi->svq->num_free >= 2+MAX_SKB_FRAGS) {

				netif_start_queue(dev);

				virtqueue_disable_cb(vi->svq);

			}

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