Re: [dpdk-dev] [PATCH v3 02/16] mbuf: add Rx timestamp flag and helpers

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

Hi Thomas,

On Tue, Nov 03, 2020 at 01:13:53AM +0100, Thomas Monjalon wrote:
> There is already a dynamic field for timestamp,
> used only for Tx scheduling with the dedicated Tx offload flag.
> The same field can be used for Rx timestamp filled by drivers.
> 
> A new dynamic flag is defined for Rx usage.
> A new function wraps the registration of both field and Rx flag.
> The type rte_mbuf_timestamp_t is defined for the API users.
> 
> After migrating all Rx timestamp usages, it will be possible
> to remove the deprecated timestamp field.
> 
> Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> ---
>  lib/librte_mbuf/rte_mbuf_dyn.c | 43 ++++++++++++++++++++++++++++++++++
>  lib/librte_mbuf/rte_mbuf_dyn.h | 33 ++++++++++++++++++++++----
>  lib/librte_mbuf/version.map    |  1 +
>  3 files changed, 72 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/librte_mbuf/rte_mbuf_dyn.c b/lib/librte_mbuf/rte_mbuf_dyn.c
> index 538a43f695..e279b23aea 100644
> --- a/lib/librte_mbuf/rte_mbuf_dyn.c
> +++ b/lib/librte_mbuf/rte_mbuf_dyn.c
> @@ -13,6 +13,7 @@
>  #include <rte_errno.h>
>  #include <rte_malloc.h>
>  #include <rte_string_fns.h>
> +#include <rte_bitops.h>
>  #include <rte_mbuf.h>
>  #include <rte_mbuf_dyn.h>
>  
> @@ -569,3 +570,45 @@ void rte_mbuf_dyn_dump(FILE *out)
>  
>  	rte_mcfg_tailq_write_unlock();
>  }
> +
> +static int
> +rte_mbuf_dyn_timestamp_register(int *field_offset, uint64_t *flag,
> +		const char *direction, const char *flag_name)
> +{
> +	static const struct rte_mbuf_dynfield field_desc = {
> +		.name = RTE_MBUF_DYNFIELD_TIMESTAMP_NAME,
> +		.size = sizeof(rte_mbuf_timestamp_t),
> +		.align = __alignof__(rte_mbuf_timestamp_t),
> +	};
> +	struct rte_mbuf_dynflag flag_desc;
> +	int offset;
> +
> +	offset = rte_mbuf_dynfield_register(&field_desc);
> +	if (offset < 0) {
> +		RTE_LOG(ERR, MBUF,
> +			"Failed to register mbuf field for timestamp\n");
> +		return -1;
> +	}
> +	if (field_offset != NULL)
> +		*field_offset = offset;
> +
> +	strlcpy(flag_desc.name, flag_name, sizeof flag_desc.name);

The rest of the flag_desc structure is not initialized to 0 (the "flags"
field).

I suggest to do it at declaration:

	struct rte_mbuf_dynflag flag_desc = { 0 };


> +	offset = rte_mbuf_dynflag_register(&flag_desc);
> +	if (offset < 0) {
> +		RTE_LOG(ERR, MBUF,
> +			"Failed to register mbuf flag for %s timestamp\n",
> +			direction);
> +		return -1;
> +	}
> +	if (flag != NULL)
> +		*flag = RTE_BIT64(offset);
> +
> +	return 0;
> +}
> +
> +int
> +rte_mbuf_dyn_rx_timestamp_register(int *field_offset, uint64_t *rx_flag)
> +{
> +	return rte_mbuf_dyn_timestamp_register(field_offset, rx_flag,
> +			"Rx", RTE_MBUF_DYNFLAG_RX_TIMESTAMP_NAME);
> +}
> diff --git a/lib/librte_mbuf/rte_mbuf_dyn.h b/lib/librte_mbuf/rte_mbuf_dyn.h
> index 0ebac88b83..2e729ddaca 100644
> --- a/lib/librte_mbuf/rte_mbuf_dyn.h
> +++ b/lib/librte_mbuf/rte_mbuf_dyn.h
> @@ -258,13 +258,36 @@ void rte_mbuf_dyn_dump(FILE *out);
>   * timestamp. The dynamic Tx timestamp flag tells whether the field contains
>   * actual timestamp value for the packets being sent, this value can be
>   * used by PMD to schedule packet sending.
> - *
> - * After PKT_RX_TIMESTAMP flag and fixed timestamp field deprecation
> - * and obsoleting, the dedicated Rx timestamp flag is supposed to be
> - * introduced and the shared dynamic timestamp field will be used
> - * to handle the timestamps on receiving datapath as well.
>   */
>  #define RTE_MBUF_DYNFIELD_TIMESTAMP_NAME "rte_dynfield_timestamp"
> +typedef uint64_t rte_mbuf_timestamp_t;
> +
> +/**
> + * Indicate that the timestamp field in the mbuf was filled by the driver.
> + */
> +#define RTE_MBUF_DYNFLAG_RX_TIMESTAMP_NAME "rte_dynflag_rx_timestamp"
> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice.
> + *
> + * Register dynamic mbuf field and flag for Rx timestamp.
> + *
> + * @param field_offset
> + *   Pointer to the offset of the registered mbuf field, can be NULL.
> + *   The same field is shared for Rx and Tx timestamp.
> + * @param rx_flag
> + *   Pointer to the mask of the registered offload flag, can be NULL.
> + * @return
> + *   0 on success, -1 otherwise.
> + *   Possible values for rte_errno:
> + *   - EEXIST: already registered with different parameters.
> + *   - EPERM: called from a secondary process.
> + *   - ENOENT: no more field or flag available.
> + *   - ENOMEM: allocation failure.
> + */
> +__rte_experimental
> +int rte_mbuf_dyn_rx_timestamp_register(int *field_offset, uint64_t *rx_flag);
>  
>  /**
>   * When PMD sees the RTE_MBUF_DYNFLAG_TX_TIMESTAMP_NAME flag set on the
> diff --git a/lib/librte_mbuf/version.map b/lib/librte_mbuf/version.map
> index a011aaead3..0b66668bff 100644
> --- a/lib/librte_mbuf/version.map
> +++ b/lib/librte_mbuf/version.map
> @@ -42,6 +42,7 @@ EXPERIMENTAL {
>  	rte_mbuf_dynflag_register;
>  	rte_mbuf_dynflag_register_bitnum;
>  	rte_mbuf_dyn_dump;
> +	rte_mbuf_dyn_rx_timestamp_register;
>  	rte_pktmbuf_copy;
>  	rte_pktmbuf_free_bulk;
>  	rte_pktmbuf_pool_create_extbuf;
> -- 
> 2.28.0
>