Re: [net-next PATCH 11/11] net: ravb: Add VLAN checksum support

Sergey Shtylyov
2024-09-30T20:36:51Z

On 9/30/24 19:08, Paul Barker wrote:

> From: Paul Barker <paul.barker.ct@bp.renesas.com>
>
> The GbEth IP supports offloading checksum calculation for VLAN-tagged
> packets, provided that the EtherType is 0x8100 and only one VLAN tag is
> present.
>
> Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>
[...]

> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index 832132d44fb4..eb7499d42a9b 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -2063,11 +2063,30 @@ static void ravb_tx_timeout_work(struct work_struct *work)
>
> static bool ravb_can_tx_csum_gbeth(struct sk_buff *skb)
> {
> - /* TODO: Need to add support for VLAN tag 802.1Q */
> - if (skb_vlan_tag_present(skb))
> + u16 net_protocol = ntohs(skb->protocol);
> +
> + /* GbEth IP can calculate the checksum if:
> + * - there are zero or one VLAN headers with TPID=0x8100
> + * - the network protocol is IPv4 or IPv6
> + * - the transport protocol is TCP, UDP or ICMP
> + * - the packet is not fragmented
> + */
> +
> + if (skb_vlan_tag_present(skb) &&
> + (skb->vlan_proto != ETH_P_8021Q || net_protocol == ETH_P_8021Q))

Not sure I understand this check... Maybe s/==/!=/?

> return false;
>
> - switch (ntohs(skb->protocol)) {
> + if (net_protocol == ETH_P_8021Q) {
> + struct vlan_hdr vhdr, *vh;
> +
> + vh = skb_header_pointer(skb, ETH_HLEN, sizeof(vhdr), &vhdr);

Hm, I thought the VLAN header starts at ETH_HLEN - 2, not at ETH_HLEN...

[...]

MBR, Sergey