[PATCH v5 5/7] docs/qapi-code-gen: update to cover trace events code generation

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

Previous commits enabled trace events generation for most of QAPI
generated code (except for tests/ and qga/). Let's update documentation
to illustrate it.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 docs/devel/qapi-code-gen.rst | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/docs/devel/qapi-code-gen.rst b/docs/devel/qapi-code-gen.rst
index feafed79b5..a3430740bd 100644
--- a/docs/devel/qapi-code-gen.rst
+++ b/docs/devel/qapi-code-gen.rst
@@ -1619,7 +1619,10 @@ Code generated for commands
 
 These are the marshaling/dispatch functions for the commands defined
 in the schema.  The generated code provides qmp_marshal_COMMAND(), and
-declares qmp_COMMAND() that the user must implement.
+declares qmp_COMMAND() that the user must implement.  The generated code
+contains trace events code.  Corresponding .trace-events file with list
+of trace events is generated too, and should be parsed by trace generator
+later to generate trace event code, see `tracing <tracing.html>`.
 
 The following files are generated:
 
@@ -1630,6 +1633,9 @@ The following files are generated:
  ``$(prefix)qapi-commands.h``
      Function prototypes for the QMP commands specified in the schema
 
+ ``$(prefix)qapi-commands.trace-events``
+     Trace events file for trace generator, see `tracing <tracing.html>`.
+
  ``$(prefix)qapi-init-commands.h``
      Command initialization prototype
 
@@ -1689,14 +1695,27 @@ Example::
             goto out;
         }
 
+        if (trace_event_get_state_backends(TRACE_QMP_ENTER_MY_COMMAND)) {
+            g_autoptr(GString) req_json = qobject_to_json(QOBJECT(args));
+
+            trace_qmp_enter_my_command(req_json->str);
+        }
+
         retval = qmp_my_command(arg.arg1, &err);
         if (err) {
+            trace_qmp_exit_my_command(error_get_pretty(err), false);
             error_propagate(errp, err);
             goto out;
         }
 
         qmp_marshal_output_UserDefOne(retval, ret, errp);
 
+        if (trace_event_get_state_backends(TRACE_QMP_EXIT_MY_COMMAND)) {
+            g_autoptr(GString) ret_json = qobject_to_json(*ret);
+
+            trace_qmp_exit_my_command(ret_json->str, true);
+        }
+
     out:
         visit_free(v);
         v = qapi_dealloc_visitor_new();
-- 
2.31.1