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Date: Wed, 16 Jun 2021 15:33:05 +0800
From: Jason Wang <jasowang@...hat.com>
To: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
"Michael S. Tsirkin" <mst@...hat.com>,
Björn Töpel <bjorn@...nel.org>,
Magnus Karlsson <magnus.karlsson@...el.com>,
Jonathan Lemon <jonathan.lemon@...il.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
KP Singh <kpsingh@...nel.org>,
virtualization@...ts.linux-foundation.org, bpf@...r.kernel.org,
"dust . li" <dust.li@...ux.alibaba.com>
Subject: Re: [PATCH net-next v5 08/15] virtio-net: split the receive_mergeable
function
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@...ux.alibaba.com>
> ---
> 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?
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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