greybus: tracing: define connection traces

Define a new gb_connection trace point event class, used to trace
events associated with the connection abstraction.  Define four basic
trace events for this--creation, drop of last reference, and when
adding or dropping any other reference.  There are certainly
more events that we might want to add, but aim is to just get the
basic framework in place.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/connection.c

@@ -10,6 +10,7 @@
 #include <linux/workqueue.h>
 
 #include "greybus.h"
+#include "greybus_trace.h"
 
 
 static void gb_connection_kref_release(struct kref *kref);
@@ -38,10 +39,14 @@ gb_connection_intf_find(struct gb_interface *intf, u16 cport_id)
 static void gb_connection_get(struct gb_connection *connection)
 {
 	kref_get(&connection->kref);
+
+	trace_gb_connection_get(connection);
 }
 
 static void gb_connection_put(struct gb_connection *connection)
 {
+	trace_gb_connection_put(connection);
+
 	kref_put(&connection->kref, gb_connection_kref_release);
 }
 
@@ -93,6 +98,8 @@ static void gb_connection_kref_release(struct kref *kref)
 
 	connection = container_of(kref, struct gb_connection, kref);
 
+	trace_gb_connection_release(connection);
+
 	kfree(connection);
 }
 
@@ -204,6 +211,8 @@ _gb_connection_create(struct gb_host_device *hd, int hd_cport_id,
 
 	mutex_unlock(&gb_connection_mutex);
 
+	trace_gb_connection_create(connection);
+
 	return connection;
 
 err_free_connection:
@@ -709,6 +718,9 @@ int gb_connection_enable(struct gb_connection *connection)
 		goto out_unlock;
 
 	ret = _gb_connection_enable(connection, true);
+	if (!ret)
+		trace_gb_connection_enable(connection);
+
 out_unlock:
 	mutex_unlock(&connection->mutex);
 
@@ -731,6 +743,9 @@ int gb_connection_enable_tx(struct gb_connection *connection)
 		goto out_unlock;
 
 	ret = _gb_connection_enable(connection, false);
+	if (!ret)
+		trace_gb_connection_enable(connection);
+
 out_unlock:
 	mutex_unlock(&connection->mutex);
 
@@ -751,6 +766,8 @@ void gb_connection_disable_rx(struct gb_connection *connection)
 	gb_connection_flush_incoming_operations(connection, -ESHUTDOWN);
 	spin_unlock_irq(&connection->lock);
 
+	trace_gb_connection_disable(connection);
+
 out_unlock:
 	mutex_unlock(&connection->mutex);
 }
@@ -793,6 +810,8 @@ void gb_connection_disable(struct gb_connection *connection)
 
 	connection->state = GB_CONNECTION_STATE_DISABLED;
 
+	trace_gb_connection_disable(connection);
+
 	/* control-connection tear down is deferred when mode switching */
 	if (!connection->mode_switch) {
 		gb_connection_svc_connection_destroy(connection);
@@ -822,6 +841,8 @@ void gb_connection_disable_forced(struct gb_connection *connection)
 	gb_connection_svc_connection_destroy(connection);
 	gb_connection_hd_cport_disable(connection);
 
+	trace_gb_connection_disable(connection);
+
 out_unlock:
 	mutex_unlock(&connection->mutex);
 }

drivers/staging/greybus/greybus_trace.h

@@ -16,6 +16,7 @@
 
 struct gb_message;
 struct gb_operation;
+struct gb_connection;
 struct gb_bundle;
 struct gb_host_device;
 
@@ -162,6 +163,80 @@ DEFINE_OPERATION_EVENT(gb_operation_put_active);
 
 #undef DEFINE_OPERATION_EVENT
 
+DECLARE_EVENT_CLASS(gb_connection,
+
+	TP_PROTO(struct gb_connection *connection),
+
+	TP_ARGS(connection),
+
+	TP_STRUCT__entry(
+		__field(int, hd_bus_id)
+		__field(u8, bundle_id)
+		/* name contains "hd_cport_id/intf_id:cport_id" */
+		__dynamic_array(char, name, sizeof(connection->name))
+		__field(enum gb_connection_state, state)
+		__field(unsigned long, flags)
+	),
+
+	TP_fast_assign(
+		__entry->hd_bus_id = connection->hd->bus_id;
+		__entry->bundle_id = connection->bundle ?
+				connection->bundle->id : BUNDLE_ID_NONE;
+		memcpy(__get_str(name), connection->name,
+					sizeof(connection->name));
+		__entry->state = connection->state;
+		__entry->flags = connection->flags;
+	),
+
+	TP_printk("hd_bus_id=%d bundle_id=0x%02x name=\"%s\" state=%u flags=0x%lx",
+		  __entry->hd_bus_id, __entry->bundle_id, __get_str(name),
+		  (unsigned int)__entry->state, __entry->flags)
+);
+
+#define DEFINE_CONNECTION_EVENT(name)					\
+		DEFINE_EVENT(gb_connection, name,			\
+				TP_PROTO(struct gb_connection *connection), \
+				TP_ARGS(connection))
+
+/*
+ * Occurs after a new connection is successfully created.
+ */
+DEFINE_CONNECTION_EVENT(gb_connection_create);
+
+/*
+ * Occurs when the last reference to a connection has been dropped,
+ * before its resources are freed.
+ */
+DEFINE_CONNECTION_EVENT(gb_connection_release);
+
+/*
+ * Occurs when a new reference to connection is added, currently
+ * only when a message over the connection is received.
+ */
+DEFINE_CONNECTION_EVENT(gb_connection_get);
+
+/*
+ * Occurs when a new reference to connection is dropped, after a
+ * a received message is handled, or when the connection is
+ * destroyed.
+ */
+DEFINE_CONNECTION_EVENT(gb_connection_put);
+
+/*
+ * Occurs when a request to enable a connection is made, either for
+ * transmit only, or for both transmit and receive.
+ */
+DEFINE_CONNECTION_EVENT(gb_connection_enable);
+
+/*
+ * Occurs when a request to disable a connection is made, either for
+ * receive only, or for both transmit and receive.  Also occurs when
+ * a request to forcefully disable a connection is made.
+ */
+DEFINE_CONNECTION_EVENT(gb_connection_disable);
+
+#undef DEFINE_CONNECTION_EVENT
+
 DECLARE_EVENT_CLASS(gb_bundle,
 
 	TP_PROTO(struct gb_bundle *bundle),