Re: [dpdk-dev] [PATCH v8 1/7] ethdev: add set ptype function

[Andrew Rybchenko <arybchenko@solarflare.com>]

On 10/3/19 12:36 AM, pbhagavatula@marvell.com wrote:
> From: Pavan Nikhilesh <pbhagavatula@marvell.com>
>
> Add `rte_eth_dev_set_supported_ptypes` function that will allow the
> application to inform the PMD the packet types it is interested in.
> Based on the ptypes set PMDs can optimize their Rx path.
>
> -If application doesn’t want any ptype information it can call
> `rte_eth_dev_set_supported_ptypes(ethdev_id, RTE_PTYPE_UNKNOWN, NULL, 0)`
> and PMD may skip packet type processing and set rte_mbuf::packet_type to
> RTE_PTYPE_UNKNOWN.
>
> -If application doesn’t call `rte_eth_dev_set_supported_ptypes` PMD can
> return `rte_mbuf::packet_type` with `rte_eth_dev_get_supported_ptypes`.
>
> -If application is interested only in L2/L3 layer, it can inform the PMD
> to update `rte_mbuf::packet_type` with L2/L3 ptype by calling
> `rte_eth_dev_set_supported_ptypes(ethdev_id,
> 		RTE_PTYPE_L2_MASK | RTE_PTYPE_L3_MASK, NULL, 0)`.
>
> Suggested-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
> Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>

With few fixes below:
Reviewed-by: Andrew Rybchenko <arybchenko@solarflare.com>

[snip]

> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
> index 17d183e1f..57bc12b56 100644
> --- a/lib/librte_ethdev/rte_ethdev.c
> +++ b/lib/librte_ethdev/rte_ethdev.c
> @@ -2602,6 +2602,65 @@ rte_eth_dev_get_supported_ptypes(uint16_t port_id, uint32_t ptype_mask,
>   	return j;
>   }
>
> +int
> +rte_eth_dev_set_supported_ptypes(uint16_t port_id, uint32_t ptype_mask,
> +				 uint32_t *set_ptypes, unsigned int num)
> +{
> +	unsigned int i, j;
> +	struct rte_eth_dev *dev;
> +	const uint32_t *all_ptypes;
> +
> +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> +	dev = &rte_eth_devices[port_id];
> +
> +	if (num > 0 && set_ptypes == NULL)
> +		return -EINVAL;
> +
> +	if (*dev->dev_ops->dev_supported_ptypes_get == NULL ||
> +			*dev->dev_ops->dev_supported_ptypes_set == NULL) {
> +		if (num > 0)
> +			set_ptypes[0] = RTE_PTYPE_UNKNOWN;
> +		return 0;
> +	}
> +
> +	if (ptype_mask == 0) {
> +		if (num > 0)
> +			set_ptypes[0] = RTE_PTYPE_UNKNOWN;
> +
> +		return (*dev->dev_ops->dev_supported_ptypes_set)(dev,
> +				ptype_mask);
> +	}
> +
> +	all_ptypes = (*dev->dev_ops->dev_supported_ptypes_get)(dev);
> +	if (all_ptypes == NULL) {
> +		if (num > 0)
> +			set_ptypes[0] = RTE_PTYPE_UNKNOWN;
> +
> +		return 0;
> +	}
> +
> +	/*
> +	 * Accodommodate as many set_ptypes as possible. If the supplied
> +	 * set_ptypes array is insufficient fill it partially.
> +	 */
> +	for (i = 0, j = 0; set_ptypes != NULL &&
> +				(all_ptypes[i] != RTE_PTYPE_UNKNOWN); ++i) {
> +		if (ptype_mask & all_ptypes[i]) {
> +			if (j < num - 1) {
> +				set_ptypes[j] = all_ptypes[i];
> +				j++;
> +				continue;
> +			}
> +			break;
> +		}
> +	}
> +
> +	if (set_ptypes != NULL)
> +		set_ptypes[j] = RTE_PTYPE_UNKNOWN;

Initially I thought that we are safe here, but now realized that we
can write more than num here, e.g. if set_ptypes is not NULL, but num is 0.
I think the right condition here is (j < num) since it guarantees that
set_ptype is not NULL as well (since num is greater than 0 if unsigned j
is less than num).

> +
> +	return (*dev->dev_ops->dev_supported_ptypes_set)(dev, ptype_mask);
> +}
> +
>   void
>   rte_eth_macaddr_get(uint16_t port_id, struct rte_ether_addr *mac_addr)
>   {
> diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
> index d9871782e..c577a9172 100644
> --- a/lib/librte_ethdev/rte_ethdev.h
> +++ b/lib/librte_ethdev/rte_ethdev.h
> @@ -2431,6 +2431,42 @@ int rte_eth_dev_fw_version_get(uint16_t port_id,
>    */
>   int rte_eth_dev_get_supported_ptypes(uint16_t port_id, uint32_t ptype_mask,
>   				     uint32_t *ptypes, int num);
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice.
> + *
> + * Inform Ethernet device of the packet types classification in which
> + * the recipient is interested.
> + *
> + * Application can use this function to set only specific ptypes that it's
> + * interested. This information can be used by the PMD to optimize Rx path.
> + *
> + * The function accepts an array `set_ptypes` allocated by the caller to
> + * store the packet types set by the driver, the last element of the array
> + * is set to RTE_PTYPE_UNKNOWN. The size of the `set_ptype` array should be
> + * `rte_eth_dev_get_supported_ptypes() + 1` else it might only be filled
> + * partially.
> + *
> + * @param port_id
> + *   The port identifier of the Ethernet device.
> + * @param ptype_mask
> + *   The ptype family that application is interested in.

I think it is better to highlight here that it should be bitwise OR of
RTE_PTYPE_*_MASK or 0.

BTW, I think it would be useful to check it to avoid misuse of the API
when, for example, RTE_PTYPE_L4_TCP is specified as ptype_mask.

> + * @param set_ptypes
> + *   An array pointer to store set packet types, allocated by caller. The
> + *   function marks the end of array with RTE_PTYPE_UNKNOWN.
> + * @param num
> + *   Size of the array pointed by param ptypes.
> + *   Should be rte_eth_dev_get_supported_ptypes() + 1 to accommodate the
> + *   set ptypes.
> + * @return
> + *   - (0) if Success.
> + *   - (-ENODEV) if *port_id* invalid.
> + *   - (-EINVAL) if *ptype_mask* is invalid (or) set_ptypes is NULL and
> + *     num > 0.
> + */
> +__rte_experimental
> +int rte_eth_dev_set_supported_ptypes(uint16_t port_id, uint32_t ptype_mask,
> +				     uint32_t *set_ptypes, unsigned int num);
>
>   /**
>    * Retrieve the MTU of an Ethernet device.
> diff --git a/lib/librte_ethdev/rte_ethdev_core.h b/lib/librte_ethdev/rte_ethdev_core.h
> index 2922d5b7c..06afd6a3d 100644
> --- a/lib/librte_ethdev/rte_ethdev_core.h
> +++ b/lib/librte_ethdev/rte_ethdev_core.h
> @@ -110,6 +110,16 @@ typedef void (*eth_dev_infos_get_t)(struct rte_eth_dev *dev,
>   typedef const uint32_t *(*eth_dev_supported_ptypes_get_t)(struct rte_eth_dev *dev);
>   /**< @internal Get supported ptypes of an Ethernet device. */
>
> +typedef int (*eth_dev_supported_ptypes_set_t)(struct rte_eth_dev *dev,
> +					      uint32_t ptype_mask);
> +/**< @internal Inform an Ethernet device about packet types in which the
> + *   recipient is interested.
> + *   Ptype_mask can have any of the following values RTE_PTYPE_UNKNOWN |
> + *   RTE_PTYPE_L2_MASK | RTE_PTYPE_L3_MASK | RTE_PTYPE_L4_MASK |
> + *   RTE_PTYPE_TUNNEL_MASK | RTE_PTYPE_INNER_L2_MASK | RTE_PTYPE_INNER_L3_MASK |
> + *   RTE_PTYPE_INNER_L4_MASK | RTE_PTYPE_ALL_MASK.
> + */
> +

I'm sorry for misunderstanding. It should be a comment before the typedef
which start from /** . So long post comments looks a bit strange.
Please, describe parameters using @param and return values using @return
and @retval.
Also there is no point to mention all RTE_PTYPE masks here to avoid
duplication and possible unsync if we have more masks.

Will you update a driver to implement it in 19.11 release cycle?
As I understand it is a requirement to add a new API.

>   typedef int (*eth_queue_start_t)(struct rte_eth_dev *dev,
>   				    uint16_t queue_id);
>   /**< @internal Start rx and tx of a queue of an Ethernet device. */

[snip]