Re: [Intel-wired-lan] [PATCH iwl-net] idpf: account for VLAN header when parsing RSC packet header

> -----Original Message-----
> From: Intel-wired-lan <[email protected]> On Behalf
> Of Joshua Hay
> Sent: Tuesday, July 28, 2026 1:09 AM
> To: [email protected]
> Cc: [email protected]
> Subject: [Intel-wired-lan] [PATCH iwl-net] idpf: account for VLAN
> header when parsing RSC packet header
>=20
> While parsing the header of a Receive Side Coalesced (RSC) packet,
> check if a VLAN tag is present and adjust the header parsing
> accordingly.
> Otherwise, Rx TCP traffic is completely broken for any VLAN interface
> whose underlying interface has RSC (rx-gro-hw) enabled.
>=20
> We only need to worry about one VLAN header since Rx packets with
> multiple VLAN headers are not candidates for RSC.
>=20
> Fixes: 3a8845af66edb ("idpf: add RX splitq napi poll support")
> Signed-off-by: Joshua Hay <[email protected]>
> Reviewed-by: Emil Tantilov <[email protected]>
> ---
>  drivers/net/ethernet/intel/idpf/idpf_txrx.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>=20
> diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> index c724d429a7aa..70553f64f770 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> +++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> @@ -3299,6 +3299,7 @@ static int idpf_rx_rsc(struct idpf_rx_queue
> *rxq, struct sk_buff *skb,
>  		       struct libeth_rx_pt decoded)
>  {
>  	u16 rsc_segments, rsc_seg_len;
> +	u16 l3_start =3D 0;
>  	bool ipv4, ipv6;
>  	int len;
>=20
> @@ -3321,7 +3322,10 @@ static int idpf_rx_rsc(struct idpf_rx_queue
> *rxq, struct sk_buff *skb,
>  	NAPI_GRO_CB(skb)->count =3D rsc_segments;
>  	skb_shinfo(skb)->gso_size =3D rsc_seg_len;
>=20
> -	skb_reset_network_header(skb);
> +	if (unlikely(eth_type_vlan(skb->protocol)))
> +		l3_start =3D VLAN_HLEN;
> +
> +	skb_set_network_header(skb, l3_start);
>=20
>  	if (ipv4) {
>  		struct iphdr *ipv4h =3D ip_hdr(skb);
> @@ -3329,7 +3333,7 @@ static int idpf_rx_rsc(struct idpf_rx_queue
> *rxq, struct sk_buff *skb,
>  		skb_shinfo(skb)->gso_type =3D SKB_GSO_TCPV4;
>=20
>  		/* Reset and set transport header offset in skb */
> -		skb_set_transport_header(skb, sizeof(struct iphdr));
> +		skb_set_transport_header(skb, l3_start + sizeof(struct
> iphdr));
>  		len =3D skb->len - skb_transport_offset(skb);
>=20
>  		/* Compute the TCP pseudo header checksum*/ @@ -3339,7
> +3343,7 @@ static int idpf_rx_rsc(struct idpf_rx_queue *rxq, struct
> sk_buff *skb,
>  		struct ipv6hdr *ipv6h =3D ipv6_hdr(skb);
>=20
>  		skb_shinfo(skb)->gso_type =3D SKB_GSO_TCPV6;
> -		skb_set_transport_header(skb, sizeof(struct ipv6hdr));
> +		skb_set_transport_header(skb, l3_start + sizeof(struct
> ipv6hdr));
>  		len =3D skb->len - skb_transport_offset(skb);
>  		tcp_hdr(skb)->check =3D
>  			~tcp_v6_check(len, &ipv6h->saddr, &ipv6h->daddr,
> 0);
> --
> 2.39.2

Reviewed-by: Aleksandr Loktionov <[email protected]>