Jason Wang <jasowang@xxxxxxxxxx> writes:
> 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.
Nice. These fields date from when the vq struct was opaque.
Applied,
Rusty.
> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> drivers/net/virtio_net.c | 16 +++-------------
> 1 file changed, 3 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index c51a988..4e1bce3 100644
> --- 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;
> --
> 1.8.3.2
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