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

[Olivier Matz <olivier.matz@6wind.com>]

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?

> Signed-off-by: Raslan Darawsheh <rasland@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?

It would help to see the specification to have a better idea of how to
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>;
	};
};

Also, you need to take care about endianness.


Regards,
Olivier