virtio-net: drop rq->max and rq->num

It looks like there's no need for those two fields:

- Unless there's a failure for the first refill try, rq->max should be always
  equal to the vring size.
- rq->num is only used to determine the condition that we need to do the refill,
  we could check vq->num_free instead.
- rq->num was required to be increased or decreased explicitly after each
  get/put which results a bad API.

So this patch removes them both to make the code simpler.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 7b17240..9bd70aa 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -72,9 +72,6 @@ struct receive_queue {
 
        struct napi_struct napi;
 
-       /* Number of input buffers, and max we've ever had. */
-       unsigned int num, max;
-
        /* Chain pages by the private ptr. */
        struct page *pages;
 
@@ -360,7 +357,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
                }
 
                page = virt_to_head_page(buf);
-               --rq->num;
 
                num_skb_frags = skb_shinfo(curr_skb)->nr_frags;
                if (unlikely(num_skb_frags == MAX_SKB_FRAGS)) {
@@ -406,7 +402,6 @@ err_skb:
                }
                page = virt_to_head_page(buf);
                put_page(page);
-               --rq->num;
        }
 err_buf:
        dev->stats.rx_dropped++;
@@ -628,10 +623,7 @@ static bool try_fill_recv(struct receive_queue *rq, gfp_t gfp)
                oom = err == -ENOMEM;
                if (err)
                        break;
-               ++rq->num;
        } while (rq->vq->num_free);
-       if (unlikely(rq->num > rq->max))
-               rq->max = rq->num;
        if (unlikely(!virtqueue_kick(rq->vq)))
                return false;
        return !oom;
@@ -699,11 +691,10 @@ again:
        while (received < budget &&
               (buf = virtqueue_get_buf(rq->vq, &len)) != NULL) {
                receive_buf(rq, buf, len);
-               --rq->num;
                received++;
        }
 
-       if (rq->num < rq->max / 2) {
+       if (rq->vq->num_free > virtqueue_get_vring_size(rq->vq) / 2) {
                if (!try_fill_recv(rq, GFP_ATOMIC))
                        schedule_delayed_work(&vi->refill, 0);
        }
@@ -1398,9 +1389,7 @@ static void free_unused_bufs(struct virtnet_info *vi)
                                give_pages(&vi->rq[i], buf);
                        else
                                dev_kfree_skb(buf);
-                       --vi->rq[i].num;
                }
-               BUG_ON(vi->rq[i].num != 0);
        }
 }
 
@@ -1671,7 +1660,8 @@ static int virtnet_probe(struct virtio_device *vdev)
                try_fill_recv(&vi->rq[i], GFP_KERNEL);
 
                /* If we didn't even get one input buffer, we're useless. */
-               if (vi->rq[i].num == 0) {
+               if (vi->rq[i].vq->num_free ==
+                   virtqueue_get_vring_size(vi->rq[i].vq)) {
                        free_unused_bufs(vi);
                        err = -ENOMEM;
                        goto free_recv_bufs;