virtio_net: Check for room in the vq before adding buffer
Saves us one cycle of alloc-add-free if the queue was full.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (modified)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index effe8c6..d445845 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -280,7 +280,7 @@
bool oom = false;
sg_init_table(sg, 2+MAX_SKB_FRAGS);
- for (;;) {
+ do {
struct skb_vnet_hdr *hdr;
skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN + NET_IP_ALIGN);
@@ -323,7 +323,7 @@
break;
}
vi->num++;
- }
+ } while (err >= num);
if (unlikely(vi->num > vi->max))
vi->max = vi->num;
vi->rvq->vq_ops->kick(vi->rvq);
@@ -341,7 +341,7 @@
if (!vi->mergeable_rx_bufs)
return try_fill_recv_maxbufs(vi, gfp);
- for (;;) {
+ do {
skb_frag_t *f;
skb = netdev_alloc_skb(vi->dev, GOOD_COPY_LEN + NET_IP_ALIGN);
@@ -375,7 +375,7 @@
break;
}
vi->num++;
- }
+ } while (err > 0);
if (unlikely(vi->num > vi->max))
vi->max = vi->num;
vi->rvq->vq_ops->kick(vi->rvq);