Re: [PATCH stable v2 2/3] virtio-net: make all RX paths handle errors consistently

Jason Wang
2013-12-27T03:19:54Z

On 12/26/2013 09:32 PM, Michael S. Tsirkin wrote:
> receive mergeable now handles errors internally.
> Do same for big and small packet paths, otherwise
> the logic is too hard to follow.
>
> Cc: Jason Wang <jasowang@redhat.com>
> Cc: David S. Miller <davem@davemloft.net>
> Acked-by: Michael Dalton <mwdalton@google.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>
> (cherry picked from commit f121159d72091f25afb22007c833e60a6845e912)
> ---
> drivers/net/virtio_net.c | 56 +++++++++++++++++++++++++++++++-----------------
> 1 file changed, 36 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 435076f..c0ed6d5 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -297,6 +297,34 @@ static struct sk_buff *page_to_skb(struct receive_queue *rq,
> return skb;
> }
>
> +static struct sk_buff *receive_small(void *buf, unsigned int len)
> +{
> + struct sk_buff * skb = buf;
> +
> + len -= sizeof(struct virtio_net_hdr);
> + skb_trim(skb, len);
> +
> + return skb;
> +}
> +
> +static struct sk_buff *receive_big(struct net_device *dev,
> + struct receive_queue *rq,
> + void *buf)
> +{
> + struct page *page = buf;
> + struct sk_buff *skb = page_to_skb(rq, page, 0);
> +
> + if (unlikely(!skb))
> + goto err;
> +
> + return skb;
> +
> +err:
> + dev->stats.rx_dropped++;
> + give_pages(rq, page);
> + return NULL;
> +}
> +
> static struct sk_buff *receive_mergeable(struct net_device *dev,
> struct receive_queue *rq,
> void *buf,
> @@ -360,7 +388,6 @@ static void receive_buf(struct receive_queue *rq, void *buf, unsigned int len)
> struct net_device *dev = vi->dev;
> struct virtnet_stats *stats = this_cpu_ptr(vi->stats);
> struct sk_buff *skb;
> - struct page *page;
> struct skb_vnet_hdr *hdr;
>
> if (unlikely(len < sizeof(struct virtio_net_hdr) + ETH_HLEN)) {
> @@ -372,26 +399,15 @@ static void receive_buf(struct receive_queue *rq, void *buf, unsigned int len)
> dev_kfree_skb(buf);
> return;
> }
> + if (vi->mergeable_rx_bufs)
> + skb = receive_mergeable(dev, rq, buf, len);
> + else if (vi->big_packets)
> + skb = receive_big(dev, rq, buf);
> + else
> + skb = receive_small(buf, len);
>
> - if (!vi->mergeable_rx_bufs && !vi->big_packets) {
> - skb = buf;
> - len -= sizeof(struct virtio_net_hdr);
> - skb_trim(skb, len);
> - } else {
> - page = buf;
> - if (vi->mergeable_rx_bufs) {
> - skb = receive_mergeable(dev, rq, page, len);
> - if (unlikely(!skb))
> - return;
> - } else {
> - skb = page_to_skb(rq, page, len);
> - if (unlikely(!skb)) {
> - dev->stats.rx_dropped++;
> - give_pages(rq, page);
> - return;
> - }
> - }
> - }
> + if (unlikely(!skb))
> + return;
>
> hdr = skb_vnet_hdr(skb);
>

Acked-by: Jason Wang <jasowang@redhat.com>