On Wed, Oct 29, 2025 at 11:09 AM Xuan Zhuo <[email protected]> wrote:
>
> Although `virtio_net_hdr_from_skb` is used in several places outside of
> `virtio-net.c`, the `hdr_len` field is only utilized by the device
> according to the specification. Therefore, we do not need to set
> `hdr_len` unless the header is actually passed to the device.
>
> Signed-off-by: Xuan Zhuo <[email protected]>
I wonder if this will cause any issue consider hdr_len is just a hint.
E.g device needs to survive from hdr_len = 0.
> ---
> include/linux/virtio_net.h | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> index 4d1780848d0e..710ae0d2d336 100644
> --- a/include/linux/virtio_net.h
> +++ b/include/linux/virtio_net.h
> @@ -218,9 +218,14 @@ static inline int virtio_net_hdr_from_skb(const struct
> sk_buff *skb,
> if (skb_is_gso(skb)) {
> struct skb_shared_info *sinfo = skb_shinfo(skb);
>
> - /* This is a hint as to how much should be linear. */
> - hdr->hdr_len = __cpu_to_virtio16(little_endian,
> - skb_headlen(skb));
> + /* In certain code paths (such as the af_packet.c receive
> path),
> + * this function may be called without a transport header.
> + * In this case, we do not need to set the hdr_len.
> + */
> + if (skb_transport_header_was_set(skb))
> + hdr->hdr_len = __cpu_to_virtio16(little_endian,
> + skb_headlen(skb));
> +
> hdr->gso_size = __cpu_to_virtio16(little_endian,
> sinfo->gso_size);
> if (sinfo->gso_type & SKB_GSO_TCPV4)
> --
> 2.32.0.3.g01195cf9f
>
Thanks
