[dpdk-dev] [RFC PATCH v2 2/7] hcdev: add event notification

[Thomas Monjalon <thomas@monjalon.net>]

Callback functions may be registered for a device event.
Callback management is per-process and not thread-safe.

The events RTE_HCDEV_EVENT_NEW and RTE_HCDEV_EVENT_DEL
are notified respectively after creation and before removal
of a device, as part of the library functions.
Some future events may be emitted from drivers.

Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
---
 lib/hcdev/hcdev.c        | 137 +++++++++++++++++++++++++++++++++++++++
 lib/hcdev/hcdev_driver.h |   7 ++
 lib/hcdev/rte_hcdev.h    |  71 ++++++++++++++++++++
 lib/hcdev/version.map    |   3 +
 4 files changed, 218 insertions(+)

diff --git a/lib/hcdev/hcdev.c b/lib/hcdev/hcdev.c
index ea587b3713..2a7ce1ccd8 100644
--- a/lib/hcdev/hcdev.c
+++ b/lib/hcdev/hcdev.c
@@ -3,6 +3,7 @@
  */
 
 #include <rte_eal.h>
+#include <rte_tailq.h>
 #include <rte_string_fns.h>
 #include <rte_errno.h>
 #include <rte_log.h>
@@ -27,6 +28,15 @@ static int16_t hcdev_max;
 /* Number of currently valid devices */
 static int16_t hcdev_count;
 
+/* Event callback object */
+struct rte_hcdev_callback {
+	TAILQ_ENTRY(rte_hcdev_callback) next;
+	rte_hcdev_callback_t *function;
+	void *user_data;
+	enum rte_hcdev_event event;
+};
+static void hcdev_free_callbacks(struct rte_hcdev *dev);
+
 int
 rte_hcdev_init(size_t dev_max)
 {
@@ -166,6 +176,7 @@ rte_hcdev_allocate(const char *name)
 	dev->info.name = dev->name;
 	dev->info.dev_id = dev_id;
 	dev->info.numa_node = -1;
+	TAILQ_INIT(&dev->callbacks);
 
 	hcdev_count++;
 	HCDEV_LOG(DEBUG, "new device %s (id %d) of total %d",
@@ -180,6 +191,7 @@ rte_hcdev_complete_new(struct rte_hcdev *dev)
 		return;
 
 	dev->state = RTE_HCDEV_STATE_INITIALIZED;
+	rte_hcdev_notify(dev, RTE_HCDEV_EVENT_NEW);
 }
 
 int
@@ -192,6 +204,9 @@ rte_hcdev_release(struct rte_hcdev *dev)
 
 	HCDEV_LOG(DEBUG, "free device %s (id %d)",
 			dev->info.name, dev->info.dev_id);
+	rte_hcdev_notify(dev, RTE_HCDEV_EVENT_DEL);
+
+	hcdev_free_callbacks(dev);
 	dev->state = RTE_HCDEV_STATE_UNUSED;
 	hcdev_count--;
 
@@ -224,6 +239,128 @@ rte_hcdev_close(int16_t dev_id)
 	return firsterr;
 }
 
+int
+rte_hcdev_callback_register(int16_t dev_id, enum rte_hcdev_event event,
+		rte_hcdev_callback_t *function, void *user_data)
+{
+	int16_t next_dev, last_dev;
+	struct rte_hcdev_callback_list *callbacks;
+	struct rte_hcdev_callback *callback;
+
+	if (!rte_hcdev_is_valid(dev_id) && dev_id != RTE_HCDEV_ID_ANY) {
+		HCDEV_LOG(ERR, "register callback of invalid ID %d", dev_id);
+		rte_errno = ENODEV;
+		return -rte_errno;
+	}
+	if (function == NULL) {
+		HCDEV_LOG(ERR, "cannot register callback without function");
+		rte_errno = EINVAL;
+		return -rte_errno;
+	}
+
+	if (dev_id == RTE_HCDEV_ID_ANY) {
+		next_dev = 0;
+		last_dev = hcdev_max - 1;
+	} else {
+		next_dev = last_dev = dev_id;
+	}
+	do {
+		callbacks = &hcdevs[next_dev].callbacks;
+
+		/* check if not already registered */
+		TAILQ_FOREACH(callback, callbacks, next) {
+			if (callback->event == event &&
+					callback->function == function &&
+					callback->user_data == user_data) {
+				HCDEV_LOG(INFO, "callback already registered");
+				return 0;
+			}
+		}
+
+		callback = malloc(sizeof(*callback));
+		if (callback == NULL) {
+			HCDEV_LOG(ERR, "cannot allocate callback");
+			return -ENOMEM;
+		}
+		callback->function = function;
+		callback->user_data = user_data;
+		callback->event = event;
+		TAILQ_INSERT_TAIL(callbacks, callback, next);
+
+	} while (++next_dev <= last_dev);
+
+	return 0;
+}
+
+int
+rte_hcdev_callback_unregister(int16_t dev_id, enum rte_hcdev_event event,
+		rte_hcdev_callback_t *function, void *user_data)
+{
+	int16_t next_dev, last_dev;
+	struct rte_hcdev_callback_list *callbacks;
+	struct rte_hcdev_callback *callback, *next_callback;
+
+	if (!rte_hcdev_is_valid(dev_id) && dev_id != RTE_HCDEV_ID_ANY) {
+		HCDEV_LOG(ERR, "unregister callback of invalid ID %d", dev_id);
+		rte_errno = ENODEV;
+		return -rte_errno;
+	}
+	if (function == NULL) {
+		HCDEV_LOG(ERR, "cannot unregister callback without function");
+		rte_errno = EINVAL;
+		return -rte_errno;
+	}
+
+	if (dev_id == RTE_HCDEV_ID_ANY) {
+		next_dev = 0;
+		last_dev = hcdev_max - 1;
+	} else {
+		next_dev = last_dev = dev_id;
+	}
+
+	do {
+		callbacks = &hcdevs[next_dev].callbacks;
+		TAILQ_FOREACH_SAFE(callback, callbacks, next, next_callback) {
+			if (callback->event != event ||
+					callback->function != function ||
+					(callback->user_data != user_data &&
+					user_data != (void *)-1))
+				continue;
+			TAILQ_REMOVE(callbacks, callback, next);
+			free(callback);
+		}
+	} while (++next_dev <= last_dev);
+
+	return 0;
+}
+
+static void
+hcdev_free_callbacks(struct rte_hcdev *dev)
+{
+	struct rte_hcdev_callback_list *callbacks;
+	struct rte_hcdev_callback *callback, *next_callback;
+
+	callbacks = &dev->callbacks;
+	TAILQ_FOREACH_SAFE(callback, callbacks, next, next_callback) {
+		TAILQ_REMOVE(callbacks, callback, next);
+		free(callback);
+	}
+}
+
+void
+rte_hcdev_notify(struct rte_hcdev *dev, enum rte_hcdev_event event)
+{
+	int16_t dev_id;
+	struct rte_hcdev_callback *callback;
+
+	dev_id = dev->info.dev_id;
+	TAILQ_FOREACH(callback, &dev->callbacks, next) {
+		if (callback->event != event || callback->function == NULL)
+			continue;
+		callback->function(dev_id, event, callback->user_data);
+	}
+}
+
 int
 rte_hcdev_info_get(int16_t dev_id, struct rte_hcdev_info *info)
 {
diff --git a/lib/hcdev/hcdev_driver.h b/lib/hcdev/hcdev_driver.h
index ca23cb9b9f..80d11bd612 100644
--- a/lib/hcdev/hcdev_driver.h
+++ b/lib/hcdev/hcdev_driver.h
@@ -12,6 +12,7 @@
 #define RTE_HCDEV_DRIVER_H
 
 #include <stdint.h>
+#include <sys/queue.h>
 
 #include <rte_dev.h>
 
@@ -43,6 +44,8 @@ struct rte_hcdev {
 	struct rte_hcdev_info info;
 	/* Driver functions. */
 	struct rte_hcdev_ops ops;
+	/* Event callback list. */
+	TAILQ_HEAD(rte_hcdev_callback_list, rte_hcdev_callback) callbacks;
 	/* Current state (used or not) in the running process. */
 	enum rte_hcdev_state state; /* Updated by this library. */
 	/* Driver-specific private data for the running process. */
@@ -64,4 +67,8 @@ void rte_hcdev_complete_new(struct rte_hcdev *dev);
 __rte_internal
 int rte_hcdev_release(struct rte_hcdev *dev);
 
+/* Call registered callbacks. No multi-process event. */
+__rte_internal
+void rte_hcdev_notify(struct rte_hcdev *dev, enum rte_hcdev_event);
+
 #endif /* RTE_HCDEV_DRIVER_H */
diff --git a/lib/hcdev/rte_hcdev.h b/lib/hcdev/rte_hcdev.h
index 83f58193c1..8131e4045a 100644
--- a/lib/hcdev/rte_hcdev.h
+++ b/lib/hcdev/rte_hcdev.h
@@ -17,6 +17,7 @@
  *
  * The API is not thread-safe.
  * Device management must be done by a single thread.
+ * TODO device rwlock for callback list
  *
  * @warning
  * @b EXPERIMENTAL: this API may change without prior notice.
@@ -31,6 +32,11 @@ extern "C" {
 
 /** Empty device ID. */
 #define RTE_HCDEV_ID_NONE -1
+/** Catch-all device ID. */
+#define RTE_HCDEV_ID_ANY INT16_MIN
+
+/** Catch-all callback data. */
+#define RTE_HCDEV_CALLBACK_ANY_DATA ((void *)-1)
 
 /** Store device info. */
 struct rte_hcdev_info {
@@ -46,6 +52,18 @@ struct rte_hcdev_info {
 	int16_t numa_node;
 };
 
+/** Flags passed in notification callback. */
+enum rte_hcdev_event {
+	/** Device is just initialized. */
+	RTE_HCDEV_EVENT_NEW,
+	/** Device is going to be released. */
+	RTE_HCDEV_EVENT_DEL,
+};
+
+/** Prototype of event callback function. */
+typedef void (rte_hcdev_callback_t)(int16_t dev_id,
+		enum rte_hcdev_event event, void *user_data);
+
 /**
  * @warning
  * @b EXPERIMENTAL: this API may change without prior notice.
@@ -142,6 +160,59 @@ int16_t rte_hcdev_find_next(int16_t dev_id);
 __rte_experimental
 int rte_hcdev_close(int16_t dev_id);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Register a function as event callback.
+ * A function may be registered multiple times for different events.
+ *
+ * @param dev_id
+ *   Device ID to get notified about.
+ *   RTE_HCDEV_ID_ANY means all devices.
+ * @param event
+ *   Device event to be registered for.
+ * @param function
+ *   Callback function to be called on event.
+ * @param user_data
+ *   Optional parameter passed in the callback.
+ *
+ * @return
+ *   0 on success, -rte_errno otherwise:
+ *   - ENODEV if invalid dev_id
+ *   - EINVAL if NULL function
+ *   - ENOMEM if out of memory
+ */
+__rte_experimental
+int rte_hcdev_callback_register(int16_t dev_id, enum rte_hcdev_event event,
+		rte_hcdev_callback_t *function, void *user_data);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Unregister for an event.
+ *
+ * @param dev_id
+ *   Device ID to be silenced.
+ *   RTE_HCDEV_ID_ANY means all devices.
+ * @param event
+ *   Registered event.
+ * @param function
+ *   Registered function.
+ * @param user_data
+ *   Optional parameter as registered.
+ *   RTE_HCDEV_CALLBACK_ANY_DATA is a catch-all.
+ *
+ * @return
+ *   0 on success, -rte_errno otherwise:
+ *   - ENODEV if invalid dev_id
+ *   - EINVAL if NULL function
+ */
+__rte_experimental
+int rte_hcdev_callback_unregister(int16_t dev_id, enum rte_hcdev_event event,
+		rte_hcdev_callback_t *function, void *user_data);
+
 /**
  * @warning
  * @b EXPERIMENTAL: this API may change without prior notice.
diff --git a/lib/hcdev/version.map b/lib/hcdev/version.map
index bc6dae6de7..24a5a5a7c4 100644
--- a/lib/hcdev/version.map
+++ b/lib/hcdev/version.map
@@ -2,6 +2,8 @@ EXPERIMENTAL {
 	global:
 
 	# added in 21.11
+	rte_hcdev_callback_register;
+	rte_hcdev_callback_unregister;
 	rte_hcdev_close;
 	rte_hcdev_count_avail;
 	rte_hcdev_find_next;
@@ -16,5 +18,6 @@ INTERNAL {
 	rte_hcdev_allocate;
 	rte_hcdev_complete_new;
 	rte_hcdev_get_by_name;
+	rte_hcdev_notify;
 	rte_hcdev_release;
 };
-- 
2.31.1