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

On 2/21/2017 6:15 PM, Jerin Jacob wrote:

On Fri, Feb 10, 2017 at 02:05:49PM +0000, Cristian Dumitrescu wrote:

quoted

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 <redacted>
---
 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.

quoted

+ * @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 <redacted>

I echo the suggestion.
otherwise, you can add
Acked-by: Hemant Agrawal <redacted>

quoted

+
+/**
  * 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