event: add function for reading unlink in progress

This commit introduces a new function in the eventdev API,
which allows applications to read the number of unlink requests
in progress on a particular port of an eventdev instance.

This information allows applications to verify when no more packets
from a particular queue (or any queue) will arrive at a port.
The application could decide to stop polling, or put the core into
a sleep state if it wishes, as it is ensured that no new packets
will arrive at a particular port anymore if all queues are unlinked.

Suggested-by: Matias Elo <matias.elo@nokia.com>
Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>

lib/librte_eventdev/rte_eventdev.c

@@ -980,6 +980,28 @@ rte_event_port_unlink(uint8_t dev_id, uint8_t port_id,
 	return diag;
 }
 
+int __rte_experimental
+rte_event_port_unlinks_in_progress(uint8_t dev_id, uint8_t port_id)
+{
+	struct rte_eventdev *dev;
+
+	RTE_EVENTDEV_VALID_DEVID_OR_ERR_RET(dev_id, -EINVAL);
+	dev = &rte_eventdevs[dev_id];
+	if (!is_valid_port(dev, port_id)) {
+		RTE_EDEV_LOG_ERR("Invalid port_id=%" PRIu8, port_id);
+		return -EINVAL;
+	}
+
+	/* Return 0 if the PMD does not implement unlinks in progress.
+	 * This allows PMDs which handle unlink synchronously to not implement
+	 * this function at all.
+	 */
+	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->port_unlinks_in_progress, 0);
+
+	return (*dev->dev_ops->port_unlinks_in_progress)(dev,
+			dev->data->ports[port_id]);
+}
+
 int
 rte_event_port_links_get(uint8_t dev_id, uint8_t port_id,
 			 uint8_t queues[], uint8_t priorities[])

lib/librte_eventdev/rte_eventdev.h

@@ -1656,12 +1656,13 @@ rte_event_port_link(uint8_t dev_id, uint8_t port_id,
  * event port designated by its *port_id* on the event device designated
  * by its *dev_id*.
  *
- * The unlink establishment shall disable the event port *port_id* from
- * receiving events from the specified event queue *queue_id*
- *
+ * The unlink call issues an async request to disable the event port *port_id*
+ * from receiving events from the specified event queue *queue_id*.
  * Event queue(s) to event port unlink establishment can be changed at runtime
  * without re-configuring the device.
  *
+ * @see rte_event_port_unlinks_in_progress() to poll for completed unlinks.
+ *
  * @param dev_id
  *   The identifier of the device.
  *
@@ -1679,21 +1680,47 @@ rte_event_port_link(uint8_t dev_id, uint8_t port_id,
  *   NULL.
  *
  * @return
- * The number of unlinks actually established. The return value can be less
+ * The number of unlinks successfully requested. The return value can be less
  * than the value of the *nb_unlinks* parameter when the implementation has the
  * limitation on specific queue to port unlink establishment or
  * if invalid parameters are specified.
  * If the return value is less than *nb_unlinks*, the remaining queues at the
- * end of queues[] are not established, and the caller has to take care of them.
+ * end of queues[] are not unlinked, and the caller has to take care of them.
  * If return value is less than *nb_unlinks* then implementation shall update
  * the rte_errno accordingly, Possible rte_errno values are
  * (-EINVAL) Invalid parameter
- *
  */
 int
 rte_event_port_unlink(uint8_t dev_id, uint8_t port_id,
 		      uint8_t queues[], uint16_t nb_unlinks);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Returns the number of unlinks in progress.
+ *
+ * This function provides the application with a method to detect when an
+ * unlink has been completed by the implementation.
+ *
+ * @see rte_event_port_unlink() to issue unlink requests.
+ *
+ * @param dev_id
+ *   The indentifier of the device.
+ *
+ * @param port_id
+ *   Event port identifier to select port to check for unlinks in progress.
+ *
+ * @return
+ * The number of unlinks that are in progress. A return of zero indicates that
+ * there are no outstanding unlink requests. A positive return value indicates
+ * the number of unlinks that are in progress, but are not yet complete.
+ * A negative return value indicates an error, -EINVAL indicates an invalid
+ * parameter passed for *dev_id* or *port_id*.
+ */
+int __rte_experimental
+rte_event_port_unlinks_in_progress(uint8_t dev_id, uint8_t port_id);
+
 /**
  * Retrieve the list of source event queues and its associated service priority
  * linked to the destination event port designated by its *port_id*

lib/librte_eventdev/rte_eventdev_pmd.h

@@ -332,6 +332,23 @@ typedef int (*eventdev_port_link_t)(struct rte_eventdev *dev, void *port,
 typedef int (*eventdev_port_unlink_t)(struct rte_eventdev *dev, void *port,
 		uint8_t queues[], uint16_t nb_unlinks);
 
+/**
+ * Unlinks in progress. Returns number of unlinks that the PMD is currently
+ * performing, but have not yet been completed.
+ *
+ * @param dev
+ *   Event device pointer
+ *
+ * @param port
+ *   Event port pointer
+ *
+ * @return
+ *   Returns the number of in-progress unlinks. Zero is returned if none are
+ *   in progress.
+ */
+typedef int (*eventdev_port_unlinks_in_progress_t)(struct rte_eventdev *dev,
+		void *port);
+
 /**
  * Converts nanoseconds to *timeout_ticks* value for rte_event_dequeue()
  *
@@ -815,6 +832,8 @@ struct rte_eventdev_ops {
 	/**< Link event queues to an event port. */
 	eventdev_port_unlink_t port_unlink;
 	/**< Unlink event queues from an event port. */
+	eventdev_port_unlinks_in_progress_t port_unlinks_in_progress;
+	/**< Unlinks in progress on an event port. */
 	eventdev_dequeue_timeout_ticks_t timeout_ticks;
 	/**< Converts ns to *timeout_ticks* value for rte_event_dequeue() */
 	eventdev_dump_t dump;

lib/librte_eventdev/rte_eventdev_version.map

@@ -96,6 +96,7 @@ EXPERIMENTAL {
 	rte_event_crypto_adapter_stats_reset;
 	rte_event_crypto_adapter_stop;
 	rte_event_eth_rx_adapter_cb_register;
+	rte_event_port_unlinks_in_progress;
 	rte_event_timer_adapter_caps_get;
 	rte_event_timer_adapter_create;
 	rte_event_timer_adapter_create_ext;