On Thu, Mar 19, 2026 at 4:15 PM Paolo Abeni <[email protected]> wrote: > > Hi, > > On 3/18/26 5:11 AM, Jason Wang wrote: > > On Wed, Mar 18, 2026 at 12:07 PM Jason Wang <[email protected]> wrote: > >> On Fri, Mar 13, 2026 at 3:59 PM Xuan Zhuo <[email protected]> > >> wrote: > >>> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h > >>> index 75dabb763c65..48de4a16a96a 100644 > >>> --- a/include/linux/virtio_net.h > >>> +++ b/include/linux/virtio_net.h > >>> @@ -207,6 +207,22 @@ static inline int virtio_net_hdr_to_skb(struct > >>> sk_buff *skb, > >>> return __virtio_net_hdr_to_skb(skb, hdr, little_endian, > >>> hdr->gso_type); > >>> } > >>> > >>> +static inline void virtio_net_set_hdrlen(const struct sk_buff *skb, > >>> + struct virtio_net_hdr *hdr, > >>> + bool little_endian) > >>> +{ > >>> + u16 hdr_len; > >>> + > >>> + hdr_len = skb_transport_offset(skb); > >>> + > >>> + if (hdr->gso_type == VIRTIO_NET_HDR_GSO_UDP_L4) > >>> + hdr_len += sizeof(struct udphdr); > >>> + else > >>> + hdr_len += tcp_hdrlen(skb); > >> > >> Ok, I think this depends on the logic inside virtio_net_hdr_from_skb() > >> > >> if (sinfo->gso_type & SKB_GSO_TCPV4) > >> hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4; > >> else if (sinfo->gso_type & SKB_GSO_TCPV6) > >> hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6; > >> else if (sinfo->gso_type & SKB_GSO_UDP_L4) > >> hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP_L4; > >> else > >> return -EINVAL; > >> > >> To be more robust, I'd suggest moving it there. > >> > >> But I have another question, the logic above depends on the headlen is > >> correctly set: > >> > >> /* This is a hint as to how much should be linear. */ > >> hdr->hdr_len = __cpu_to_virtio16(little_endian, > >> skb_headlen(skb)); > >> > >> Is the headlen guaranteed to be correct in all cases (e.g for nested > >> setups or dodgy packets?) > > > > Speak too fast, I miss > > > > hdr_len = skb_transport_offset(skb); > > > > This is probably another call to > > > > 1) Move virtio_net_set_hdrlen() inside virtio_net_hdr_from_skb() or > > 2) call virtio_net_set_hdrlen() inside virtio_net_hdr_from_skb(). > > It looks like that the above leads to more complex code with a bunch of > additional conditionals, which possibly the compiler can't optimize out, > and IMHO not nice layering violation, see the already mentioned previous > iteration: > > https://lore.kernel.org/all/[email protected]/ > > What about instead simply rename virtio_net_set_hdrlen() to > __virtio_net_set_hdrlen(), virtio_net_set_tnl_hdrlen() to > __virtio_net_set_tnl_hdrlen(), and add explicitly mention in a comment > that such functions must be invoked only after virtio_net_hdr_from_skb() > validation?
Works for me. Thanks > > /P >
