kunit: Add APIs for managing devices

Tests for drivers often require a struct device to pass to other
functions. While it's possible to create these with
root_device_register(), or to use something like a platform device, this
is both a misuse of those APIs, and can be difficult to clean up after,
for example, a failed assertion.

Add some KUnit-specific functions for registering and unregistering a
struct device:
- kunit_device_register()
- kunit_device_register_with_driver()
- kunit_device_unregister()

These helpers allocate a on a 'kunit' bus which will either probe the
driver passed in (kunit_device_register_with_driver), or will create a
stub driver (kunit_device_register) which is cleaned up on test shutdown.

Devices are automatically unregistered on test shutdown, but can be
manually unregistered earlier with kunit_device_unregister() in order
to, for example, test device release code.

Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
This commit is contained in:
davidgow@google.com 2023-12-15 15:39:08 +08:00 committed by Shuah Khan
parent e9f0e21ceb
commit d03c720e03
8 changed files with 475 additions and 2 deletions

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@ -11,3 +11,12 @@ state on a per-test basis, register custom cleanup actions, and more.
.. kernel-doc:: include/kunit/resource.h
:internal:
Managed Devices
---------------
Functions for using KUnit-managed struct device and struct device_driver.
Include ``kunit/device.h`` to use these.
.. kernel-doc:: include/kunit/device.h
:internal:

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@ -797,3 +797,53 @@ structures as shown below:
KUnit is not enabled, or if no test is running in the current task, it will do
nothing. This compiles down to either a no-op or a static key check, so will
have a negligible performance impact when no test is running.
Managing Fake Devices and Drivers
---------------------------------
When testing drivers or code which interacts with drivers, many functions will
require a ``struct device`` or ``struct device_driver``. In many cases, setting
up a real device is not required to test any given function, so a fake device
can be used instead.
KUnit provides helper functions to create and manage these fake devices, which
are internally of type ``struct kunit_device``, and are attached to a special
``kunit_bus``. These devices support managed device resources (devres), as
described in Documentation/driver-api/driver-model/devres.rst
To create a KUnit-managed ``struct device_driver``, use ``kunit_driver_create()``,
which will create a driver with the given name, on the ``kunit_bus``. This driver
will automatically be destroyed when the corresponding test finishes, but can also
be manually destroyed with ``driver_unregister()``.
To create a fake device, use the ``kunit_device_register()``, which will create
and register a device, using a new KUnit-managed driver created with ``kunit_driver_create()``.
To provide a specific, non-KUnit-managed driver, use ``kunit_device_register_with_driver()``
instead. Like with managed drivers, KUnit-managed fake devices are automatically
cleaned up when the test finishes, but can be manually cleaned up early with
``kunit_device_unregister()``.
The KUnit devices should be used in preference to ``root_device_register()``, and
instead of ``platform_device_register()`` in cases where the device is not otherwise
a platform device.
For example:
.. code-block:: c
#include <kunit/device.h>
static void test_my_device(struct kunit *test)
{
struct device *fake_device;
const char *dev_managed_string;
// Create a fake device.
fake_device = kunit_device_register(test, "my_device");
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, fake_device)
// Pass it to functions which need a device.
dev_managed_string = devm_kstrdup(fake_device, "Hello, World!");
// Everything is cleaned up automatically when the test ends.
}

80
include/kunit/device.h Normal file
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@ -0,0 +1,80 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* KUnit basic device implementation
*
* Helpers for creating and managing fake devices for KUnit tests.
*
* Copyright (C) 2023, Google LLC.
* Author: David Gow <davidgow@google.com>
*/
#ifndef _KUNIT_DEVICE_H
#define _KUNIT_DEVICE_H
#if IS_ENABLED(CONFIG_KUNIT)
#include <kunit/test.h>
struct device;
struct device_driver;
/**
* kunit_driver_create() - Create a struct device_driver attached to the kunit_bus
* @test: The test context object.
* @name: The name to give the created driver.
*
* Creates a struct device_driver attached to the kunit_bus, with the name @name.
* This driver will automatically be cleaned up on test exit.
*
* Return: a stub struct device_driver, managed by KUnit, with the name @name.
*/
struct device_driver *kunit_driver_create(struct kunit *test, const char *name);
/**
* kunit_device_register() - Create a struct device for use in KUnit tests
* @test: The test context object.
* @name: The name to give the created device.
*
* Creates a struct kunit_device (which is a struct device) with the given name,
* and a corresponding driver. The device and driver will be cleaned up on test
* exit, or when kunit_device_unregister is called. See also
* kunit_device_register_with_driver, if you wish to provide your own
* struct device_driver.
*
* Return: a pointer to a struct device which will be cleaned up when the test
* exits, or an error pointer if the device could not be allocated or registered.
*/
struct device *kunit_device_register(struct kunit *test, const char *name);
/**
* kunit_device_register_with_driver() - Create a struct device for use in KUnit tests
* @test: The test context object.
* @name: The name to give the created device.
* @drv: The struct device_driver to associate with the device.
*
* Creates a struct kunit_device (which is a struct device) with the given
* name, and driver. The device will be cleaned up on test exit, or when
* kunit_device_unregister is called. See also kunit_device_register, if you
* wish KUnit to create and manage a driver for you.
*
* Return: a pointer to a struct device which will be cleaned up when the test
* exits, or an error pointer if the device could not be allocated or registered.
*/
struct device *kunit_device_register_with_driver(struct kunit *test,
const char *name,
const struct device_driver *drv);
/**
* kunit_device_unregister() - Unregister a KUnit-managed device
* @test: The test context object which created the device
* @dev: The device.
*
* Unregisters and destroys a struct device which was created with
* kunit_device_register or kunit_device_register_with_driver. If KUnit created
* a driver, cleans it up as well.
*/
void kunit_device_unregister(struct kunit *test, struct device *dev);
#endif
#endif

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@ -7,7 +7,8 @@ kunit-objs += test.o \
assert.o \
try-catch.o \
executor.o \
attributes.o
attributes.o \
device.o
ifeq ($(CONFIG_KUNIT_DEBUGFS),y)
kunit-objs += debugfs.o

17
lib/kunit/device-impl.h Normal file
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@ -0,0 +1,17 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* KUnit internal header for device helpers
*
* Header for KUnit-internal driver / bus management.
*
* Copyright (C) 2023, Google LLC.
* Author: David Gow <davidgow@google.com>
*/
#ifndef _KUNIT_DEVICE_IMPL_H
#define _KUNIT_DEVICE_IMPL_H
// For internal use only -- registers the kunit_bus.
int kunit_bus_init(void);
#endif //_KUNIT_DEVICE_IMPL_H

181
lib/kunit/device.c Normal file
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@ -0,0 +1,181 @@
// SPDX-License-Identifier: GPL-2.0
/*
* KUnit-managed device implementation
*
* Implementation of struct kunit_device helpers for fake devices whose
* lifecycle is managed by KUnit.
*
* Copyright (C) 2023, Google LLC.
* Author: David Gow <davidgow@google.com>
*/
#include <linux/device.h>
#include <kunit/test.h>
#include <kunit/device.h>
#include <kunit/resource.h>
#include "device-impl.h"
/* Wrappers for use with kunit_add_action() */
KUNIT_DEFINE_ACTION_WRAPPER(device_unregister_wrapper, device_unregister, struct device *);
KUNIT_DEFINE_ACTION_WRAPPER(driver_unregister_wrapper, driver_unregister, struct device_driver *);
/* The root device for the KUnit bus, parent of all kunit_devices. */
static struct device *kunit_bus_device;
/* A device owned by a KUnit test. */
struct kunit_device {
struct device dev;
/* The KUnit test which owns this device. */
struct kunit *owner;
/* If the driver is managed by KUnit and unique to this device. */
const struct device_driver *driver;
};
#define to_kunit_device(d) container_of_const(d, struct kunit_device, dev)
static struct bus_type kunit_bus_type = {
.name = "kunit",
};
/* Register the 'kunit_bus' used for fake devices. */
int kunit_bus_init(void)
{
int error;
kunit_bus_device = root_device_register("kunit");
if (!kunit_bus_device)
return -ENOMEM;
error = bus_register(&kunit_bus_type);
if (error)
bus_unregister(&kunit_bus_type);
return error;
}
/* Release a 'fake' KUnit device. */
static void kunit_device_release(struct device *d)
{
kfree(to_kunit_device(d));
}
/**
* Create and register a KUnit-managed struct device_driver on the kunit_bus.
* Returns an error pointer on failure.
*/
struct device_driver *kunit_driver_create(struct kunit *test, const char *name)
{
struct device_driver *driver;
int err = -ENOMEM;
driver = kunit_kzalloc(test, sizeof(*driver), GFP_KERNEL);
if (!driver)
return ERR_PTR(err);
driver->name = name;
driver->bus = &kunit_bus_type;
driver->owner = THIS_MODULE;
err = driver_register(driver);
if (err) {
kunit_kfree(test, driver);
return ERR_PTR(err);
}
kunit_add_action(test, driver_unregister_wrapper, driver);
return driver;
}
EXPORT_SYMBOL_GPL(kunit_driver_create);
/* Helper which creates a kunit_device, attaches it to the kunit_bus*/
static struct kunit_device *kunit_device_register_internal(struct kunit *test,
const char *name,
const struct device_driver *drv)
{
struct kunit_device *kunit_dev;
int err = -ENOMEM;
kunit_dev = kzalloc(sizeof(*kunit_dev), GFP_KERNEL);
if (!kunit_dev)
return ERR_PTR(err);
kunit_dev->owner = test;
err = dev_set_name(&kunit_dev->dev, "%s.%s", test->name, name);
if (err) {
kfree(kunit_dev);
return ERR_PTR(err);
}
kunit_dev->dev.release = kunit_device_release;
kunit_dev->dev.bus = &kunit_bus_type;
kunit_dev->dev.parent = kunit_bus_device;
err = device_register(&kunit_dev->dev);
if (err) {
put_device(&kunit_dev->dev);
return ERR_PTR(err);
}
kunit_add_action(test, device_unregister_wrapper, &kunit_dev->dev);
return kunit_dev;
}
/**
* Create and register a new KUnit-managed device, using the user-supplied device_driver.
* On failure, returns an error pointer.
*/
struct device *kunit_device_register_with_driver(struct kunit *test,
const char *name,
const struct device_driver *drv)
{
struct kunit_device *kunit_dev = kunit_device_register_internal(test, name, drv);
if (IS_ERR_OR_NULL(kunit_dev))
return ERR_CAST(kunit_dev);
return &kunit_dev->dev;
}
EXPORT_SYMBOL_GPL(kunit_device_register_with_driver);
/**
* Create and register a new KUnit-managed device, including a matching device_driver.
* On failure, returns an error pointer.
*/
struct device *kunit_device_register(struct kunit *test, const char *name)
{
struct device_driver *drv;
struct kunit_device *dev;
drv = kunit_driver_create(test, name);
if (IS_ERR(drv))
return ERR_CAST(drv);
dev = kunit_device_register_internal(test, name, drv);
if (IS_ERR(dev)) {
kunit_release_action(test, driver_unregister_wrapper, (void *)drv);
return ERR_CAST(dev);
}
/* Request the driver be freed. */
dev->driver = drv;
return &dev->dev;
}
EXPORT_SYMBOL_GPL(kunit_device_register);
/* Unregisters a KUnit-managed device early (including the driver, if automatically created). */
void kunit_device_unregister(struct kunit *test, struct device *dev)
{
const struct device_driver *driver = to_kunit_device(dev)->driver;
kunit_release_action(test, device_unregister_wrapper, dev);
if (driver)
kunit_release_action(test, driver_unregister_wrapper, (void *)driver);
}
EXPORT_SYMBOL_GPL(kunit_device_unregister);

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@ -5,9 +5,13 @@
* Copyright (C) 2019, Google LLC.
* Author: Brendan Higgins <brendanhiggins@google.com>
*/
#include "linux/gfp_types.h"
#include <kunit/test.h>
#include <kunit/test-bug.h>
#include <linux/device.h>
#include <kunit/device.h>
#include "string-stream.h"
#include "try-catch-impl.h"
@ -687,6 +691,134 @@ static struct kunit_case kunit_current_test_cases[] = {
{}
};
static void test_dev_action(void *priv)
{
*(void **)priv = (void *)1;
}
static void kunit_device_test(struct kunit *test)
{
struct device *test_device;
long action_was_run = 0;
test_device = kunit_device_register(test, "my_device");
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, test_device);
// Add an action to verify cleanup.
devm_add_action(test_device, test_dev_action, &action_was_run);
KUNIT_EXPECT_EQ(test, action_was_run, 0);
kunit_device_unregister(test, test_device);
KUNIT_EXPECT_EQ(test, action_was_run, 1);
}
static void kunit_device_cleanup_test(struct kunit *test)
{
struct device *test_device;
long action_was_run = 0;
test_device = kunit_device_register(test, "my_device");
KUNIT_ASSERT_NOT_NULL(test, test_device);
/* Add an action to verify cleanup. */
devm_add_action(test_device, test_dev_action, &action_was_run);
KUNIT_EXPECT_EQ(test, action_was_run, 0);
/* Force KUnit to run cleanup early. */
kunit_cleanup(test);
KUNIT_EXPECT_EQ(test, action_was_run, 1);
}
struct driver_test_state {
bool driver_device_probed;
bool driver_device_removed;
long action_was_run;
};
static int driver_probe_hook(struct device *dev)
{
struct kunit *test = kunit_get_current_test();
struct driver_test_state *state = (struct driver_test_state *)test->priv;
state->driver_device_probed = true;
return 0;
}
static int driver_remove_hook(struct device *dev)
{
struct kunit *test = kunit_get_current_test();
struct driver_test_state *state = (struct driver_test_state *)test->priv;
state->driver_device_removed = true;
return 0;
}
static void kunit_device_driver_test(struct kunit *test)
{
struct device_driver *test_driver;
struct device *test_device;
struct driver_test_state *test_state = kunit_kzalloc(test, sizeof(*test_state), GFP_KERNEL);
test->priv = test_state;
test_driver = kunit_driver_create(test, "my_driver");
// This can fail with an error pointer.
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, test_driver);
test_driver->probe = driver_probe_hook;
test_driver->remove = driver_remove_hook;
test_device = kunit_device_register_with_driver(test, "my_device", test_driver);
// This can fail with an error pointer.
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, test_device);
// Make sure the probe function was called.
KUNIT_ASSERT_TRUE(test, test_state->driver_device_probed);
// Add an action to verify cleanup.
devm_add_action(test_device, test_dev_action, &test_state->action_was_run);
KUNIT_EXPECT_EQ(test, test_state->action_was_run, 0);
kunit_device_unregister(test, test_device);
test_device = NULL;
// Make sure the remove hook was called.
KUNIT_ASSERT_TRUE(test, test_state->driver_device_removed);
// We're going to test this again.
test_state->driver_device_probed = false;
// The driver should not automatically be destroyed by
// kunit_device_unregister, so we can re-use it.
test_device = kunit_device_register_with_driver(test, "my_device", test_driver);
// This can fail with an error pointer.
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, test_device);
// Probe was called again.
KUNIT_ASSERT_TRUE(test, test_state->driver_device_probed);
// Everything is automatically freed here.
}
static struct kunit_case kunit_device_test_cases[] = {
KUNIT_CASE(kunit_device_test),
KUNIT_CASE(kunit_device_cleanup_test),
KUNIT_CASE(kunit_device_driver_test),
{}
};
static struct kunit_suite kunit_device_test_suite = {
.name = "kunit_device",
.test_cases = kunit_device_test_cases,
};
static struct kunit_suite kunit_current_test_suite = {
.name = "kunit_current",
.test_cases = kunit_current_test_cases,
@ -694,6 +826,6 @@ static struct kunit_suite kunit_current_test_suite = {
kunit_test_suites(&kunit_try_catch_test_suite, &kunit_resource_test_suite,
&kunit_log_test_suite, &kunit_status_test_suite,
&kunit_current_test_suite);
&kunit_current_test_suite, &kunit_device_test_suite);
MODULE_LICENSE("GPL v2");

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@ -19,6 +19,7 @@
#include <linux/sched.h>
#include "debugfs.h"
#include "device-impl.h"
#include "hooks-impl.h"
#include "string-stream.h"
#include "try-catch-impl.h"
@ -900,6 +901,8 @@ static int __init kunit_init(void)
kunit_install_hooks();
kunit_debugfs_init();
kunit_bus_init();
#ifdef CONFIG_MODULES
return register_module_notifier(&kunit_mod_nb);
#else