On Wed, 16 Jun 2021 15:33:05 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote:
>
> 在 2021/6/10 下午4:22, Xuan Zhuo 写道:
> > receive_mergeable() is too complicated, so this function is split here.
> > One is to make the function more readable. On the other hand, the two
> > independent functions will be called separately in subsequent patches.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> > ---
> > drivers/net/virtio_net.c | 181 ++++++++++++++++++++++++---------------
> > 1 file changed, 111 insertions(+), 70 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 3fd87bf2b2ad..989aba600e63 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -733,6 +733,109 @@ static struct page *xdp_linearize_page(struct receive_queue *rq,
> > return NULL;
> > }
> >
> > +static void merge_drop_follow_bufs(struct net_device *dev,
> > + struct receive_queue *rq,
> > + u16 num_buf,
> > + struct virtnet_rq_stats *stats)
>
>
> Patch looks good. Nit here, I guess we need a better name, how about
> "merge_buffers()" for this and "drop_buffers()" for the next function?
The name sounds good.
Thanks.
>
> Thanks
>
>
> > +{
> > + struct page *page;
> > + unsigned int len;
> > + void *buf;
> > +
> > + while (num_buf-- > 1) {
> > + buf = virtqueue_get_buf(rq->vq, &len);
> > + if (unlikely(!buf)) {
> > + pr_debug("%s: rx error: %d buffers missing\n",
> > + dev->name, num_buf);
> > + dev->stats.rx_length_errors++;
> > + break;
> > + }
> > + stats->bytes += len;
> > + page = virt_to_head_page(buf);
> > + put_page(page);
> > + }
> > +}
> > +
> > +static struct sk_buff *merge_receive_follow_bufs(struct net_device *dev,
> > + struct virtnet_info *vi,
> > + struct receive_queue *rq,
> > + struct sk_buff *head_skb,
> > + u16 num_buf,
> > + struct virtnet_rq_stats *stats)
> > +{
> > + struct sk_buff *curr_skb;
> > + unsigned int truesize;
> > + unsigned int len, num;
> > + struct page *page;
> > + void *buf, *ctx;
> > + int offset;
> > +
> > + curr_skb = head_skb;
> > + num = num_buf;
> > +
> > + while (--num_buf) {
> > + int num_skb_frags;
> > +
> > + buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx);
> > + if (unlikely(!buf)) {
> > + pr_debug("%s: rx error: %d buffers out of %d missing\n",
> > + dev->name, num_buf, num);
> > + dev->stats.rx_length_errors++;
> > + goto err_buf;
> > + }
> > +
> > + stats->bytes += len;
> > + page = virt_to_head_page(buf);
> > +
> > + truesize = mergeable_ctx_to_truesize(ctx);
> > + if (unlikely(len > truesize)) {
> > + pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
> > + dev->name, len, (unsigned long)ctx);
> > + dev->stats.rx_length_errors++;
> > + goto err_skb;
> > + }
> > +
> > + num_skb_frags = skb_shinfo(curr_skb)->nr_frags;
> > + if (unlikely(num_skb_frags == MAX_SKB_FRAGS)) {
> > + struct sk_buff *nskb = alloc_skb(0, GFP_ATOMIC);
> > +
> > + if (unlikely(!nskb))
> > + goto err_skb;
> > + if (curr_skb == head_skb)
> > + skb_shinfo(curr_skb)->frag_list = nskb;
> > + else
> > + curr_skb->next = nskb;
> > + curr_skb = nskb;
> > + head_skb->truesize += nskb->truesize;
> > + num_skb_frags = 0;
> > + }
> > + if (curr_skb != head_skb) {
> > + head_skb->data_len += len;
> > + head_skb->len += len;
> > + head_skb->truesize += truesize;
> > + }
> > + offset = buf - page_address(page);
> > + if (skb_can_coalesce(curr_skb, num_skb_frags, page, offset)) {
> > + put_page(page);
> > + skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1,
> > + len, truesize);
> > + } else {
> > + skb_add_rx_frag(curr_skb, num_skb_frags, page,
> > + offset, len, truesize);
> > + }
> > + }
> > +
> > + return head_skb;
> > +
> > +err_skb:
> > + put_page(page);
> > + merge_drop_follow_bufs(dev, rq, num_buf, stats);
> > +err_buf:
> > + stats->drops++;
> > + dev_kfree_skb(head_skb);
> > + return NULL;
> > +}
> > +
> > static struct sk_buff *receive_small(struct net_device *dev,
> > struct virtnet_info *vi,
> > struct receive_queue *rq,
> > @@ -909,7 +1012,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> > u16 num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers);
> > struct page *page = virt_to_head_page(buf);
> > int offset = buf - page_address(page);
> > - struct sk_buff *head_skb, *curr_skb;
> > + struct sk_buff *head_skb;
> > struct bpf_prog *xdp_prog;
> > unsigned int truesize = mergeable_ctx_to_truesize(ctx);
> > unsigned int headroom = mergeable_ctx_to_headroom(ctx);
> > @@ -1054,65 +1157,15 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> >
> > head_skb = page_to_skb(vi, rq, page, offset, len, truesize, !xdp_prog,
> > metasize, !!headroom);
> > - curr_skb = head_skb;
> > -
> > - if (unlikely(!curr_skb))
> > + if (unlikely(!head_skb))
> > goto err_skb;
> > - while (--num_buf) {
> > - int num_skb_frags;
> >
> > - buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx);
> > - if (unlikely(!buf)) {
> > - pr_debug("%s: rx error: %d buffers out of %d missing\n",
> > - dev->name, num_buf,
> > - virtio16_to_cpu(vi->vdev,
> > - hdr->num_buffers));
> > - dev->stats.rx_length_errors++;
> > - goto err_buf;
> > - }
> > -
> > - stats->bytes += len;
> > - page = virt_to_head_page(buf);
> > -
> > - truesize = mergeable_ctx_to_truesize(ctx);
> > - if (unlikely(len > truesize)) {
> > - pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
> > - dev->name, len, (unsigned long)ctx);
> > - dev->stats.rx_length_errors++;
> > - goto err_skb;
> > - }
> > -
> > - num_skb_frags = skb_shinfo(curr_skb)->nr_frags;
> > - if (unlikely(num_skb_frags == MAX_SKB_FRAGS)) {
> > - struct sk_buff *nskb = alloc_skb(0, GFP_ATOMIC);
> > -
> > - if (unlikely(!nskb))
> > - goto err_skb;
> > - if (curr_skb == head_skb)
> > - skb_shinfo(curr_skb)->frag_list = nskb;
> > - else
> > - curr_skb->next = nskb;
> > - curr_skb = nskb;
> > - head_skb->truesize += nskb->truesize;
> > - num_skb_frags = 0;
> > - }
> > - if (curr_skb != head_skb) {
> > - head_skb->data_len += len;
> > - head_skb->len += len;
> > - head_skb->truesize += truesize;
> > - }
> > - offset = buf - page_address(page);
> > - if (skb_can_coalesce(curr_skb, num_skb_frags, page, offset)) {
> > - put_page(page);
> > - skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1,
> > - len, truesize);
> > - } else {
> > - skb_add_rx_frag(curr_skb, num_skb_frags, page,
> > - offset, len, truesize);
> > - }
> > - }
> > + if (num_buf > 1)
> > + head_skb = merge_receive_follow_bufs(dev, vi, rq, head_skb,
> > + num_buf, stats);
> > + if (head_skb)
> > + ewma_pkt_len_add(&rq->mrg_avg_pkt_len, head_skb->len);
> >
> > - ewma_pkt_len_add(&rq->mrg_avg_pkt_len, head_skb->len);
> > return head_skb;
> >
> > err_xdp:
> > @@ -1120,19 +1173,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> > stats->xdp_drops++;
> > err_skb:
> > put_page(page);
> > - while (num_buf-- > 1) {
> > - buf = virtqueue_get_buf(rq->vq, &len);
> > - if (unlikely(!buf)) {
> > - pr_debug("%s: rx error: %d buffers missing\n",
> > - dev->name, num_buf);
> > - dev->stats.rx_length_errors++;
> > - break;
> > - }
> > - stats->bytes += len;
> > - page = virt_to_head_page(buf);
> > - put_page(page);
> > - }
> > -err_buf:
> > + merge_drop_follow_bufs(dev, rq, num_buf, stats);
> > stats->drops++;
> > dev_kfree_skb(head_skb);
> > xdp_xmit:
>
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