[dpdk-dev] [PATCH v4 1/2] ethdev: add new ext hdr for gtp psc

Raslan Darawsheh rasland at nvidia.com
Tue Apr 13 09:45:46 CEST 2021


Hi and sorry for late response, 


> -----Original Message-----
> From: Olivier Matz <olivier.matz at 6wind.com>
> Sent: Thursday, April 8, 2021 5:11 PM
> To: Raslan Darawsheh <rasland at nvidia.com>
> Cc: dev at dpdk.org; ferruh.yigit at intel.com; Ori Kam <orika at nvidia.com>;
> andrew.rybchenko at oktetlabs.ru; ivan.malov at oktetlabs.ru;
> ying.a.wang at intel.com; Slava Ovsiienko <viacheslavo at nvidia.com>; Shiri
> Kuzin <shirik at nvidia.com>
> Subject: Re: [PATCH v4 1/2] ethdev: add new ext hdr for gtp psc
> 
> On Thu, Apr 08, 2021 at 12:37:27PM +0000, Raslan Darawsheh wrote:
> > Hi Olivier,
> >
> > > -----Original Message-----
> > > From: Olivier Matz <olivier.matz at 6wind.com>
> > > Sent: Thursday, April 8, 2021 3:30 PM
> > > To: Raslan Darawsheh <rasland at nvidia.com>
> > > Cc: dev at dpdk.org; ferruh.yigit at intel.com; Ori Kam <orika at nvidia.com>;
> > > andrew.rybchenko at oktetlabs.ru; ivan.malov at oktetlabs.ru;
> > > ying.a.wang at intel.com; Slava Ovsiienko <viacheslavo at nvidia.com>; Shiri
> > > Kuzin <shirik at nvidia.com>
> > > Subject: Re: [PATCH v4 1/2] ethdev: add new ext hdr for gtp psc
> > >
> > > Hi Raslan,
> > >
> > > On Sun, Apr 04, 2021 at 10:45:51AM +0300, Raslan Darawsheh wrote:
> > > > Define new rte header for gtp PDU session container
> > > > based on RFC 38415-g30
> > >
> > > Do you have a link to this RFC?
> > Yes sure,
> >
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fww
> w.3gpp.org%2Fftp%2FSpecs%2Farchive%2F38_series%2F38.415%2F38415-
> g30.zip&data=04%7C01%7Crasland%40nvidia.com%7C5279dde172024bc
> d1f6b08d8fa981668%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C6
> 37534878435191995%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMD
> AiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=
> LuD7%2FvJgqJbZ78ncaM7UrpiLNPUt7zbPPfSMemyb2Y8%3D&reserved
> =0
> >
> > >
> > > > Signed-off-by: Raslan Darawsheh <rasland at nvidia.com>
> > > > ---
> > > >  lib/librte_net/rte_gtp.h | 34
> ++++++++++++++++++++++++++++++++++
> > > >  1 file changed, 34 insertions(+)
> > > >
> > > > diff --git a/lib/librte_net/rte_gtp.h b/lib/librte_net/rte_gtp.h
> > > > index 6a6f9b238d..088b0b5a53 100644
> > > > --- a/lib/librte_net/rte_gtp.h
> > > > +++ b/lib/librte_net/rte_gtp.h
> > > > @@ -61,6 +61,40 @@ struct rte_gtp_hdr_ext_word {
> > > >  	uint8_t next_ext;     /**< Next Extension Header Type. */
> > > >  }  __rte_packed;
> > > >
> > > > +/**
> > > > + * Optional extension for GTP with next_ext set to 0x85
> > > > + * defined based on RFC 38415-g30.
> > > > + */
> > > > +__extension__
> > > > +struct rte_gtp_psc_hdr {
> > > > +	uint8_t ext_hdr_len; /**< PDU ext hdr len in multiples of 4 bytes */
> > > > +	uint8_t type:4; /**< PDU type */
> > > > +	uint8_t qmp:1; /**< Qos Monitoring Packet */
> > > > +	union {
> > > > +		struct {
> > > > +			uint8_t snp:1; /**< Sequence number presence */
> > > > +			uint8_t spare_dl1:2; /**< spare down link bits */
> > > > +		};
> > > > +		struct {
> > > > +			uint8_t dl_delay_ind:1; /**< dl delay result presence
> > > */
> > > > +			uint8_t ul_delay_ind:1; /**< ul delay result presence
> > > */
> > > > +			uint8_t snp_ul1:1; /**< Sequence number presence
> > > ul */
> > > > +		};
> > > > +	};
> > > > +	union {
> > > > +		struct {
> > > > +			uint8_t ppp:1; /**< Paging policy presence */
> > > > +			uint8_t rqi:1; /**< Reflective Qos Indicator */
> > > > +		};
> > > > +		struct {
> > > > +			uint8_t n_delay_ind:1; /**< N3/N9 delay result
> > > presence */
> > > > +			uint8_t spare_ul2:1; /**< spare up link bits */
> > > > +		};
> > > > +	};
> > > > +	uint8_t qfi:6; /**< Qos Flow Identifier */
> > > > +	uint8_t data[0]; /**< data feilds */
> > > > +} __rte_packed;
> > >
> > > With this header, sizeof(rte_gtp_psc_hdr) = 5, is it really expected?
> > The data[0] is variable length data, I guess I should send another version to
> mention that in the comment maybe.
> > The header size according to the spec should be 4 octets aligned in general.
> 
> What I wanted to highlight is that using union of structs containing
> bitfields does not work as you expect: each union is at least 1 byte.
> This results in a structure that does not match the expected header.
I see thanks for explaining.
> 
> > >
> > > It would help to see the specification to have a better idea of how to
> > Sure, I've just posted the link above, please let me know of any suggestion
> that you have, and I'll be glad to do accordingly.
> >
> > > split, but a possible solution is to do something like this:
> > >
> > > struct rte_gtp_psc_generic_hdr {
> > > 	uint8_t ext_hdr_len;
> > > 	uint8_t type:4
> > > 	uint8_t qmp:1;
> > > 	uint8_t pad:3;
> > > };
> > >
> > > struct rte_gtp_psc_<name1>_hdr {
> > > 	uint8_t ext_hdr_len;
> > > 	uint8_t type:4
> > > 	uint8_t qmp:1;
> > > 	uint8_t uint8_t snp:1;
> > > 	uint8_t spare_dl1:2;
> > > 	...
> > > };
> > >
> > > ...
> > >
> > > struct rte_gtp_psc_hdr {
> > > 	union {
> > > 		struct rte_gtp_psc_generic_hdr generic;
> > > 		struct rte_gtp_psc_<name1>_hdr <name1>;
> > > 		struct rte_gtp_psc_<name2>_hdr <name2>;
> > > 	};
> > > };
> 
> From what I see in the documation, I think this approach should
> work. From afar, I suggest:
> 
> struct rte_gtp_psc_generic_hdr {
> #if big endian
> 	uint8_t type:4
> 	uint8_t qmp:1;
> 	uint8_t pad:3;
> #else
> 	uint8_t pad:3;
> 	uint8_t qmp:1;
> 	uint8_t type:4
> #endif
> };
> 
> struct rte_gtp_psc_type0_hdr {
> #if big endian
> 	uint8_t type:4
> 	uint8_t qmp:1;
> 	uint8_t snp:1;
> 	uint8_t spare:2;
> 
> 	uint8_t ppp:1;
> 	...
> #else
> 	uint8_t pad:3;
> 	uint8_t qmp:1;
> 	uint8_t type:4
> 	uint8_t spare:2;
> 	uint8_t snp:1;
> 
> 	...
> #endif
> 	uint8_t data[0]; /* for variable fields */
> };
> 
> struct rte_gtp_psc_type1_hdr {
> 	... same for fixed fields of type1
> 
> 
> 	uint8_t data[0]; /* for variable fields */
> };
> 
Sure, will consider and do it this way in the next version.

> I don't see in the spec where is the reference to ext_hdr_len.
> 
The ext_hdr_len is part of the definition for all ext_hdrs see this link for more details:
https://en.wikipedia.org/wiki/GPRS_Tunnelling_Protocol
So, it's not mentioned in the doc.

> Regards,
> Olivier


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