linux/kernel/trace/synth_event_gen_test.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Test module for in-kernel synthetic event creation and generation.
 *
 * Copyright (C) 2019 Tom Zanussi <[email protected]>
 */

#include <linux/module.h>
#include <linux/trace_events.h>

/*
 * This module is a simple test of basic functionality for in-kernel
 * synthetic event creation and generation, the first and second tests
 * using synth_event_gen_cmd_start() and synth_event_add_field(), the
 * third uses synth_event_create() to do it all at once with a static
 * field array.
 *
 * Following that are a few examples using the created events to test
 * various ways of tracing a synthetic event.
 *
 * To test, select CONFIG_SYNTH_EVENT_GEN_TEST and build the module.
 * Then:
 *
 * # insmod kernel/trace/synth_event_gen_test.ko
 * # cat /sys/kernel/tracing/trace
 *
 * You should see several events in the trace buffer -
 * "create_synth_test", "empty_synth_test", and several instances of
 * "gen_synth_test".
 *
 * To remove the events, remove the module:
 *
 * # rmmod synth_event_gen_test
 *
 */

static struct trace_event_file *create_synth_test;
static struct trace_event_file *empty_synth_test;
static struct trace_event_file *gen_synth_test;

/*
 * Test to make sure we can create a synthetic event, then add more
 * fields.
 */
static int __init test_gen_synth_cmd(void)
{ … }

/*
 * Test to make sure we can create an initially empty synthetic event,
 * then add all the fields.
 */
static int __init test_empty_synth_event(void)
{ … }

static struct synth_field_desc create_synth_test_fields[] = …;

/*
 * Test synthetic event creation all at once from array of field
 * descriptors.
 */
static int __init test_create_synth_event(void)
{ … }

/*
 * Test tracing a synthetic event by reserving trace buffer space,
 * then filling in fields one after another.
 */
static int __init test_add_next_synth_val(void)
{ … }

/*
 * Test tracing a synthetic event by reserving trace buffer space,
 * then filling in fields using field names, which can be done in any
 * order.
 */
static int __init test_add_synth_val(void)
{ … }

/*
 * Test tracing a synthetic event all at once from array of values.
 */
static int __init test_trace_synth_event(void)
{ … }

static int __init synth_event_gen_test_init(void)
{ … }

static void __exit synth_event_gen_test_exit(void)
{ … }

module_init(synth_event_gen_test_init)
module_exit(synth_event_gen_test_exit)

MODULE_AUTHOR(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_LICENSE(…) …;