Re: [PATCH v2 1/9] virtio_net: disable the hole mechanism for xdp

Jason Wang
2022-12-27T06:31:10Z

在 2022/12/20 22:14, Heng Qi 写道:
> XDP core assumes that the frame_size of xdp_buff and the length of
> the frag are PAGE_SIZE. The hole may cause the processing of xdp to
> fail, so we disable the hole mechanism when xdp is set.
>
> Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
> Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> ---
> drivers/net/virtio_net.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 9cce7dec7366..443aa7b8f0ad 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1419,8 +1419,11 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi,
> /* To avoid internal fragmentation, if there is very likely not
> * enough space for another buffer, add the remaining space to
> * the current buffer.
> + * XDP core assumes that frame_size of xdp_buff and the length
> + * of the frag are PAGE_SIZE, so we disable the hole mechanism.
> */
> - len += hole;
> + if (!headroom)
> + len += hole;

Is this only a requirement of multi-buffer XDP? If not, it need to be
backported to stable.

Thanks

> alloc_frag->offset += hole;
> }
>