Re: [dpdk-dev] [RFC PATCH] mbuf: fix to update documentation of PKT_RX_QINQ_STRIPPED

[Andrew Rybchenko <arybchenko@solarflare.com>]

On 12/16/19 6:16 AM, Somnath Kotur wrote:
> Certain hardware may be able to strip and/or save only the outermost
> VLAN instead of both the VLANs in the mbuf in a QinQ scenario.
> To handle such cases, we could re-interpret setting of just PKT_RX_QINQ_STRIPPED
> to indicate that only the outermost VLAN has been stripped by the hardware and
> saved in mbuf->vlan_tci_outer.
> Only When both PKT_RX_QINQ_STRIPPED and PKT_RX_VLAN_STRIPPED are set, the 2 vlans
> have been stripped by the hardware and their tci are saved in mbuf->vlan_tci (inner)
> and mbuf->vlan_tci_outer (outer).
> 
> Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
> Signed-off-by: JP Lee <jongpil.lee@broadcom.com>
> ---
>  lib/librte_mbuf/rte_mbuf_core.h | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/librte_mbuf/rte_mbuf_core.h b/lib/librte_mbuf/rte_mbuf_core.h
> index 9a8557d..db1070b 100644
> --- a/lib/librte_mbuf/rte_mbuf_core.h
> +++ b/lib/librte_mbuf/rte_mbuf_core.h
> @@ -124,12 +124,19 @@
>  #define PKT_RX_FDIR_FLX      (1ULL << 14)
>  
>  /**
> - * The 2 vlans have been stripped by the hardware and their tci are
> - * saved in mbuf->vlan_tci (inner) and mbuf->vlan_tci_outer (outer).
> + * The outer vlan has been stripped by the hardware and their tci are
> + * saved in mbuf->vlan_tci_outer (outer).
>   * This can only happen if vlan stripping is enabled in the RX
>   * configuration of the PMD.
> - * When PKT_RX_QINQ_STRIPPED is set, the flags (PKT_RX_VLAN |
> - * PKT_RX_VLAN_STRIPPED | PKT_RX_QINQ) must also be set.
> + * When PKT_RX_QINQ_STRIPPED is set, the flags (PKT_RX_VLAN |  PKT_RX_QINQ)
> + * must also be set.
> + * When both PKT_RX_QINQ_STRIPPED and PKT_RX_VLAN_STRIPPED are set, the 2 vlans
> + * have been stripped by the hardware and their tci are saved in
> + * mbuf->vlan_tci (inner) and mbuf->vlan_tci_outer (outer).
> + * This can only happen if vlan stripping is enabled in the RX configuration
> + * of the PMD.
> + * When PKT_RX_QINQ_STRIPPED and PKT_RX_VLAN_STRIPPED are set,
> + * (PKT_RX_VLAN | PKT_RX_QINQ) must also be set.
>   */
>  #define PKT_RX_QINQ_STRIPPED (1ULL << 15)
>  

I always thought that PKT_RX_VLAN_STRIPPED means *one* VLAN
stripped regardless if it is outer (if the packet is double
tagged) or inner (if only one VLAN tag was present).

That's why PKT_RX_QINQ_STRIPPED description says that *two*
VLANs have been stripped.

What is the problem with such approach?