Re: [dpdk-dev] [PATCH 1/2] ethdev: add capability control API

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

On Fri, Feb 10, 2017 at 02:05:49PM +0000, Cristian Dumitrescu wrote:
> The rte_flow feature breaks the current monolithic approach for ethdev and
> introduces the new generic flow API to ethdev using a plugin-like approach.
> 
> Basically, the rte_flow API is still logically part of ethdev:
> - It extends the ethdev functionality: rte_flow is a new feature/capability
>   of ethdev;
> - all its functions work on an Ethernet device: the first parameter of the
>   rte_flow functions is Ethernet device port ID.
> 
> At the same time, the rte_flow API is a sort of capability plugin for ethdev:
> - the rte_flow API functions have their own name space: they are called
>   rte_flow_operationXYZ() as opposed to rte_eth_dev_flow_operationXYZ());
> - the rte_flow API functions are placed in separate files in the same
>   librte_ether folder as opposed to rte_ethdev.[hc].
> 
> The way it works is by using the existing ethdev API function
> rte_eth_dev_filter_ctrl() to query the current Ethernet device port ID for the
> support of the rte_flow capability and return the pointer to the
> rte_flow operations when supported and NULL otherwise:
> 
> struct rte_flow_ops *eth_flow_ops;
> int rte = rte_eth_dev_filter_ctrl(eth_port_id,
> 	RTE_ETH_FILTER_GENERIC, RTE_ETH_FILTER_GET, &eth_flow_ops);
> 
> Unfortunately, the rte_flow opportunistically uses the rte_eth_dev_filter_ctrl()
> API function, which is applicable just to RX-side filters as opposed to
> introducing a mechanism that could be used by any capability in a generic way.
> 
> This is the gap that addressed by the current patch. This mechanism is intended
> to be used to introduce new capabilities into ethdev in a modular plugin-like
> approach, such as hierarchical scheduler. Over time, if agreed, it can also be
> used for exposing the existing Ethernet device capabilities in a modular way,
> such as: xstats, filters, multicast, mirroring, tunnels, time stamping, eeprom,
> bypass, etc.
> 
> Signed-off-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
> ---
>  lib/librte_ether/rte_ethdev.c          | 13 +++++++++++++
>  lib/librte_ether/rte_ethdev.h          | 29 +++++++++++++++++++++++++++++
>  lib/librte_ether/rte_ether_version.map |  7 +++++++
>  3 files changed, 49 insertions(+)
> 
> diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
> index eb0a94a..ae187c4 100644
> --- a/lib/librte_ether/rte_ethdev.c
> +++ b/lib/librte_ether/rte_ethdev.c
> @@ -2802,6 +2802,19 @@ rte_eth_dev_filter_ctrl(uint8_t port_id, enum rte_filter_type filter_type,
>  	return (*dev->dev_ops->filter_ctrl)(dev, filter_type, filter_op, arg);
>  }
>  
> +int
> +rte_eth_dev_capability_control(uint8_t port_id, enum rte_eth_capability cap,
> +	void *arg)
> +{
> +	struct rte_eth_dev *dev;
> +
> +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> +
> +	dev = &rte_eth_devices[port_id];
> +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->cap_ctrl, -ENOTSUP);
> +	return (*dev->dev_ops->cap_ctrl)(dev, cap, arg);
> +}
> +
>  void *
>  rte_eth_add_rx_callback(uint8_t port_id, uint16_t queue_id,
>  		rte_rx_callback_fn fn, void *user_param)
> diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
> index c17bbda..43ffb9e 100644
> --- a/lib/librte_ether/rte_ethdev.h
> +++ b/lib/librte_ether/rte_ethdev.h
> @@ -1073,6 +1073,12 @@ TAILQ_HEAD(rte_eth_dev_cb_list, rte_eth_dev_callback);
>   * structure associated with an Ethernet device.
>   */
>  
> +enum rte_eth_capability {
> +	RTE_ETH_CAPABILITY_FLOW = 0, /**< Flow */
> +	RTE_ETH_CAPABILITY_SCHED, /**< Hierarchical Scheduler */
> +	RTE_ETH_CAPABILITY_MAX
> +};
> +
>  typedef int  (*eth_dev_configure_t)(struct rte_eth_dev *dev);
>  /**< @internal Ethernet device configuration. */
>  
> @@ -1427,6 +1433,10 @@ typedef int (*eth_filter_ctrl_t)(struct rte_eth_dev *dev,
>  				 void *arg);
>  /**< @internal Take operations to assigned filter type on an Ethernet device */
>  
> +typedef int (*eth_capability_control_t)(struct rte_eth_dev *dev,
> +	enum rte_eth_capability cap, void *arg);
> +/**< @internal Take capability operations on an Ethernet device */
> +
>  typedef int (*eth_get_dcb_info)(struct rte_eth_dev *dev,
>  				 struct rte_eth_dcb_info *dcb_info);
>  /**< @internal Get dcb information on an Ethernet device */
> @@ -1548,6 +1558,8 @@ struct eth_dev_ops {
>  	eth_timesync_adjust_time   timesync_adjust_time; /** Adjust the device clock. */
>  	eth_timesync_read_time     timesync_read_time; /** Get the device clock time. */
>  	eth_timesync_write_time    timesync_write_time; /** Set the device clock time. */
> +
> +	eth_capability_control_t   cap_ctrl; /**< capability control. */
>  };
>  
>  /**
> @@ -3890,6 +3902,23 @@ int rte_eth_dev_filter_ctrl(uint8_t port_id, enum rte_filter_type filter_type,
>  			enum rte_filter_op filter_op, void *arg);
>  
>  /**
> + * Take capability operations on an Ethernet device.
> + *
> + * @param port_id
> + *   The port identifier of the Ethernet device.
> + * @param cap
> + *   The capability of the Ethernet device
> + * @param arg
> + *   A pointer to arguments defined specifically for the operation.

Better to add _out_ for output  parameter.
@param[out] arg.

> + * @return
> + *   - (0) if successful.
> + *   - (-ENOTSUP) if hardware doesn't support.
> + *   - (-ENODEV) if *port_id* invalid.
> + */
> +int rte_eth_dev_capability_control(uint8_t port_id,
> +	enum rte_eth_capability cap, void *arg);


I like the idea of "plugin" interface to ethdev to accommodate
hierarchical scheduler ops with different name space like rte_flow.
Though I don't have strong opinion on the API
name, I think its better to have something end with _ops_get instead of
capability_control

With that suggestion,

Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>

> +
> +/**
>   * Get DCB information on an Ethernet device.
>   *
>   * @param port_id
> diff --git a/lib/librte_ether/rte_ether_version.map b/lib/librte_ether/rte_ether_version.map
> index c6c9d0d..d00cb5c 100644
> --- a/lib/librte_ether/rte_ether_version.map
> +++ b/lib/librte_ether/rte_ether_version.map
> @@ -154,3 +154,10 @@ DPDK_17.02 {
>  	rte_flow_validate;
>  
>  } DPDK_16.11;
> +
> +DPDK_17.05 {
> +	global:
> +
> +	rte_eth_dev_capability_control;
> +
> +} DPDK_17.02;
> -- 
> 2.5.0
>