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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: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Rusty Russell 2012-10-16 23:56:14 +10:30
parent 7bedc7dc7c
commit 9ed4cb0734
1 changed files with 13 additions and 20 deletions
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33
drivers/net/virtio_net.c
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@ -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 {
dev->stats.tx_fifo_errors++;
if (net_ratelimit())
dev_warn(&dev->dev,
"Unexpected TX queue failure: %d\n",
capacity);
}
/* 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", 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);
}