Re: [dpdk-dev] [PATCH v4 2/2] ethdev: update qfi definition

[Ori Kam <orika@nvidia.com>]

Hi Raslan,

> -----Original Message-----
> From: Raslan Darawsheh <rasland@nvidia.com>
> Subject: RE: [PATCH v4 2/2] ethdev: update qfi definition
> 
> Hi,
> 
> > -----Original Message-----
> > From: Ferruh Yigit <ferruh.yigit@intel.com>
> > Sent: Tuesday, April 6, 2021 7:10 PM
> > To: Raslan Darawsheh <rasland@nvidia.com>; dev@dpdk.org; Ori Kam
> > <orika@nvidia.com>; andrew.rybchenko@oktetlabs.ru
> > Cc: ivan.malov@oktetlabs.ru; ying.a.wang@intel.com;
> > olivier.matz@6wind.com; Slava Ovsiienko <viacheslavo@nvidia.com>; Shiri
> > Kuzin <shirik@nvidia.com>; stable@dpdk.org; David Marchand
> > <david.marchand@redhat.com>; NBU-Contact-Thomas Monjalon
> > <thomas@monjalon.net>
> > Subject: Re: [PATCH v4 2/2] ethdev: update qfi definition
> >
> > On 4/4/2021 8:45 AM, Raslan Darawsheh wrote:
> > > qfi field is 8 bits which represent single bit for
> > > PPP (paging Policy Presence) single bit for RQI
> > > (Reflective QoS Indicator) and 6 bits for qfi
> > > (QoS Flow Identifier) based on RFC 38415-g30
> > >
> > > This update the doxygen format and the mask for qfi
> > > to properly identify the full 8 bits of the field.
> > >
> > > note: changing the default mask would cause different
> > > patterns generated by testpmd.
> > >
> > > Fixes: 346553db5bd1 ("ethdev: add GTP extension header to flow API")
> > > Cc: ying.a.wang@intel.com
> > > Cc: stable@dpdk.org
> > >
> > > Signed-off-by: Raslan Darawsheh <rasland@nvidia.com>
> > > ---
> > >   doc/guides/testpmd_app_ug/testpmd_funcs.rst |  3 ++-
> > >   lib/librte_ethdev/rte_flow.h                | 20 +++++++++++++++++---
> > >   2 files changed, 19 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> > b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> > > index f59eb8a27d..dd39c4c3c2 100644
> > > --- a/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> > > +++ b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> > > @@ -3742,7 +3742,8 @@ This section lists supported pattern items and
> > their attributes, if any.
> > >   - ``gtp_psc``: match GTP PDU extension header with type 0x85.
> > >
> > >     - ``pdu_type {unsigned}``: PDU type.
> > > -  - ``qfi {unsigned}``: QoS flow identifier.
> > > +
> > > +  - ``qfi {unsigned}``: PPP, RQI and QoS flow identifier.
> > >
> > >   - ``pppoes``, ``pppoed``: match PPPoE header.
> > >
> > > diff --git a/lib/librte_ethdev/rte_flow.h b/lib/librte_ethdev/rte_flow.h
> > > index 6cc57136ac..20b4389429 100644
> > > --- a/lib/librte_ethdev/rte_flow.h
> > > +++ b/lib/librte_ethdev/rte_flow.h
> > > @@ -20,6 +20,7 @@
> > >   #include <rte_arp.h>
> > >   #include <rte_common.h>
> > >   #include <rte_ether.h>
> > > +#include <rte_gtp.h>
> > >   #include <rte_icmp.h>
> > >   #include <rte_ip.h>
> > >   #include <rte_sctp.h>
> > > @@ -1421,16 +1422,29 @@ static const struct rte_flow_item_meta
> > rte_flow_item_meta_mask = {
> > >    *
> > >    * Matches a GTP PDU extension header with type 0x85.
> > >    */
> > > +RTE_STD_C11
> > >   struct rte_flow_item_gtp_psc {
> > > -	uint8_t pdu_type; /**< PDU type. */
> > > -	uint8_t qfi; /**< QoS flow identifier. */
> > > +	union {
> > > +		struct {
> > > +			/*
> > > +			 * These fields are retained for compatibility.
> > > +			 * Please switch to the new header field below.
> > > +			 */
> > > +			uint8_t pdu_type; /**< PDU type. */
> > > +			uint8_t qfi; /**< PPP, RQI, QoS flow identifier. */
> > > +
> > > +		};
> > > +		struct rte_gtp_psc_hdr hdr;
> > > +	};
> > >   };
> >
> > This will change the struct size even with union, since old version is missing
> > all fields from protocol header. Struct size will go from 2 --> 5 bytes [1].
> >
> > Since this is public struct, we can't change its size.
> >
> > @Ori, Andrew,
> >
> > Do you have a suggestion for next step?
> >

I think Ferruh is right, and I think that we should at this point just update the documentation.
Sorry for the detour 
Just small comment about the original  patch.
I don’t think you should change the default mask since it may break existing apps.

> > - We can still add the "struct rte_gtp_psc_hdr", and add a deprecation notice
> > for "struct rte_flow_item_gtp_psc" to say it will use  "struct
> > rte_gtp_psc_hdr"
> > on 21.11.
> >
> > - And for this release use the Raslan's first version:
> >    -	uint8_t qfi; /**< QoS flow identifier. */
> >    +	uint8_t qfi; /**< PPP, RQI, QoS flow identifier. */
> >
> >
> > Does it make sense? Any comments?
> >
> @Ori Kam, @andrew.rybchenko@oktetlabs.ru,
> This is a kind remainder of this patch,
> 
> >
> >
> > [1]
> > struct rte_gtp_psc_hdr {
> >          uint8_t                    ext_hdr_len;          /*     0     1 */
> >          uint8_t                    type:4;               /*     1: 0  1 */
> >          uint8_t                    qmp:1;                /*     1: 4  1 */
> >
> >          /* XXX 3 bits hole, try to pack */
> >
> >          union {
> >                  struct {
> >                          uint8_t    snp:1;                /*     2: 0  1 */
> >                          uint8_t    spare_dl1:2;          /*     2: 1  1 */
> >                  };                                       /*     2     1 */
> >                  struct {
> >                          uint8_t    dl_delay_ind:1;       /*     2: 0  1 */
> >                          uint8_t    ul_delay_ind:1;       /*     2: 1  1 */
> >                          uint8_t    snp_ul1:1;            /*     2: 2  1 */
> >                  };                                       /*     2     1 */
> >          };                                               /*     2     1 */
> >          union {
> >                  struct {
> >                          uint8_t    ppp:1;                /*     3: 0  1 */
> >                          uint8_t    rqi:1;                /*     3: 1  1 */
> >                  };                                       /*     3     1 */
> >                  struct {
> >                          uint8_t    n_delay_ind:1;        /*     3: 0  1 */
> >                          uint8_t    spare_ul2:1;          /*     3: 1  1 */
> >                  };                                       /*     3     1 */
> >          };                                               /*     3     1 */
> >          uint8_t                    qfi:6;                /*     4: 0  1 */
> >
> >          /* XXX 2 bits hole, try to pack */
> >
> >          uint8_t                    data[];               /*     5     0 */
> >
> >          /* size: 5, cachelines: 1, members: 7 */
> >          /* sum members: 3 */
> >          /* sum bitfield members: 11 bits, bit holes: 2, sum bit holes: 5 bits */
> >          /* last cacheline: 5 bytes */
> > };
> >
> > >
> > >   /** Default mask for RTE_FLOW_ITEM_TYPE_GTP_PSC. */
> > >   #ifndef __cplusplus
> > >   static const struct rte_flow_item_gtp_psc
> > >   rte_flow_item_gtp_psc_mask = {
> > > -	.qfi = 0x3f,
> > > +	.hdr.ppp = 1,
> > > +	.hdr.rqi = 1,
> > > +	.hdr.qfi = 0x3f,
> > >   };
> > >   #endif
> > >
> > >