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>

1 files changed, 13 insertions, 20 deletions

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 6c094c88424e..7c7f5a94ca4f 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -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);
                         }