[PATCH v2 0/3] drivers: base: Don't match device with NULL of_node/fwnode/etc + tests

[PATCH v2 0/3] drivers: base: Don't match device with NULL of_node/fwnode/etc + tests

[Brian Norris]

This series:
1. makes the behavior of_find_device_by_node(),
   bus_find_device_by_of_node(), bus_find_device_by_fwnode(), etc., more
   consistent when provided with a NULL node/handle;
2. adds kunit tests to validate the new NULL-argument behavior; and
3. makes some related improvements and refactoring for the drivers/base/
   kunit tests.

This series aims to prevent problems like the ones resolved in commit
5c8418cf4025 ("PCI/pwrctrl: Unregister platform device only if one
actually exists").

Changes in v2:
 * Add Rob's Reviewed-by
 * CC LKML (oops!)
 * Keep "devm" and "match" tests in separate suites

Brian Norris (3):
  drivers: base: Don't match devices with NULL of_node/fwnode/etc
  drivers: base: test: Enable device model tests with KUNIT_ALL_TESTS
  drivers: base: test: Add ...find_device_by...(... NULL) tests

 drivers/base/core.c                      |  8 ++---
 drivers/base/test/Kconfig                |  1 +
 drivers/base/test/platform-device-test.c | 42 +++++++++++++++++++++++-
 3 files changed, 46 insertions(+), 5 deletions(-)

-- 
2.47.0.338.g60cca15819-goog

[PATCH v2 1/3] drivers: base: Don't match devices with NULL of_node/fwnode/etc

[Brian Norris]

of_find_device_by_node(), bus_find_device_by_of_node(),
bus_find_device_by_fwnode(), ..., all produce arbitrary results when
provided with a NULL of_node, fwnode, ACPI handle, etc. This is
counterintuitive, and the source of a few bugs, such as the one fixed by
commit 5c8418cf4025 ("PCI/pwrctrl: Unregister platform device only if
one actually exists").

It's hard to imagine a good reason that these device_match_*() APIs
should return 'true' for a NULL argument. Augment these to return 0
(false).

Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
---

Changes in v2:
 * Add Rob's Reviewed-by

 drivers/base/core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 94865c9d8adc..2b7b13fc36d7 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -5246,13 +5246,13 @@ EXPORT_SYMBOL_GPL(device_match_name);
 
 int device_match_of_node(struct device *dev, const void *np)
 {
-	return dev->of_node == np;
+	return np && dev->of_node == np;
 }
 EXPORT_SYMBOL_GPL(device_match_of_node);
 
 int device_match_fwnode(struct device *dev, const void *fwnode)
 {
-	return dev_fwnode(dev) == fwnode;
+	return fwnode && dev_fwnode(dev) == fwnode;
 }
 EXPORT_SYMBOL_GPL(device_match_fwnode);
 
@@ -5264,13 +5264,13 @@ EXPORT_SYMBOL_GPL(device_match_devt);
 
 int device_match_acpi_dev(struct device *dev, const void *adev)
 {
-	return ACPI_COMPANION(dev) == adev;
+	return adev && ACPI_COMPANION(dev) == adev;
 }
 EXPORT_SYMBOL(device_match_acpi_dev);
 
 int device_match_acpi_handle(struct device *dev, const void *handle)
 {
-	return ACPI_HANDLE(dev) == handle;
+	return handle && ACPI_HANDLE(dev) == handle;
 }
 EXPORT_SYMBOL(device_match_acpi_handle);
 
-- 
2.47.0.338.g60cca15819-goog

Re: [PATCH v2 1/3] drivers: base: Don't match devices with NULL of_node/fwnode/etc

[Rafael J. Wysocki]

On Thu, Dec 12, 2024 at 1:32 AM Brian Norris <briannorris@chromium.org> wrote:
>
> of_find_device_by_node(), bus_find_device_by_of_node(),
> bus_find_device_by_fwnode(), ..., all produce arbitrary results when
> provided with a NULL of_node, fwnode, ACPI handle, etc. This is
> counterintuitive, and the source of a few bugs, such as the one fixed by
> commit 5c8418cf4025 ("PCI/pwrctrl: Unregister platform device only if
> one actually exists").
>
> It's hard to imagine a good reason that these device_match_*() APIs
> should return 'true' for a NULL argument. Augment these to return 0
> (false).
>
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> Reviewed-by: Rob Herring (Arm) <robh@kernel.org>

For the ACPI part

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
>
> Changes in v2:
>  * Add Rob's Reviewed-by
>
>  drivers/base/core.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 94865c9d8adc..2b7b13fc36d7 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -5246,13 +5246,13 @@ EXPORT_SYMBOL_GPL(device_match_name);
>
>  int device_match_of_node(struct device *dev, const void *np)
>  {
> -       return dev->of_node == np;
> +       return np && dev->of_node == np;
>  }
>  EXPORT_SYMBOL_GPL(device_match_of_node);
>
>  int device_match_fwnode(struct device *dev, const void *fwnode)
>  {
> -       return dev_fwnode(dev) == fwnode;
> +       return fwnode && dev_fwnode(dev) == fwnode;
>  }
>  EXPORT_SYMBOL_GPL(device_match_fwnode);
>
> @@ -5264,13 +5264,13 @@ EXPORT_SYMBOL_GPL(device_match_devt);
>
>  int device_match_acpi_dev(struct device *dev, const void *adev)
>  {
> -       return ACPI_COMPANION(dev) == adev;
> +       return adev && ACPI_COMPANION(dev) == adev;
>  }
>  EXPORT_SYMBOL(device_match_acpi_dev);
>
>  int device_match_acpi_handle(struct device *dev, const void *handle)
>  {
> -       return ACPI_HANDLE(dev) == handle;
> +       return handle && ACPI_HANDLE(dev) == handle;
>  }
>  EXPORT_SYMBOL(device_match_acpi_handle);
>
> --
> 2.47.0.338.g60cca15819-goog
>

[PATCH v2 2/3] drivers: base: test: Enable device model tests with KUNIT_ALL_TESTS

[Brian Norris]

Per commit bebe94b53eb7 ("drivers: base: default KUNIT_* fragments to
KUNIT_ALL_TESTS"), it seems like we should default to KUNIT_ALL_TESTS.

This enables these platform_device tests for common configurations, such
as with:
  ./tools/testing/kunit/kunit.py run

Signed-off-by: Brian Norris <briannorris@chromium.org>
---

(no changes since v1)

 drivers/base/test/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/base/test/Kconfig b/drivers/base/test/Kconfig
index 5c7fac80611c..2756870615cc 100644
--- a/drivers/base/test/Kconfig
+++ b/drivers/base/test/Kconfig
@@ -12,6 +12,7 @@ config TEST_ASYNC_DRIVER_PROBE
 config DM_KUNIT_TEST
 	tristate "KUnit Tests for the device model" if !KUNIT_ALL_TESTS
 	depends on KUNIT
+	default KUNIT_ALL_TESTS
 
 config DRIVER_PE_KUNIT_TEST
 	tristate "KUnit Tests for property entry API" if !KUNIT_ALL_TESTS
-- 
2.47.0.338.g60cca15819-goog

[PATCH v2 3/3] drivers: base: test: Add ...find_device_by...(... NULL) tests

[Brian Norris]

We recently updated these device_match*() (and therefore, various
*find_device_by*()) functions to return a consistent 'false' value when
trying to match a NULL handle. Add tests for this.

This provides regression-testing coverage for the sorts of bugs that
underly commit 5c8418cf4025 ("PCI/pwrctrl: Unregister platform device
only if one actually exists").

Signed-off-by: Brian Norris <briannorris@chromium.org>
---

Changes in v2:
 * Keep "devm" and "match" tests in separate suites

 drivers/base/test/platform-device-test.c | 42 +++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/drivers/base/test/platform-device-test.c b/drivers/base/test/platform-device-test.c
index ea05b8785743..c8d4b0a385f2 100644
--- a/drivers/base/test/platform-device-test.c
+++ b/drivers/base/test/platform-device-test.c
@@ -3,6 +3,8 @@
 #include <kunit/resource.h>
 
 #include <linux/device.h>
+#include <linux/device/bus.h>
+#include <linux/of_platform.h>
 #include <linux/platform_device.h>
 
 #define DEVICE_NAME "test"
@@ -217,7 +219,45 @@ static struct kunit_suite platform_device_devm_test_suite = {
 	.test_cases = platform_device_devm_tests,
 };
 
-kunit_test_suite(platform_device_devm_test_suite);
+static void platform_device_find_by_null_test(struct kunit *test)
+{
+	struct platform_device *pdev;
+	int ret;
+
+	pdev = platform_device_alloc(DEVICE_NAME, PLATFORM_DEVID_NONE);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
+
+	ret = platform_device_add(pdev);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	KUNIT_EXPECT_PTR_EQ(test, of_find_device_by_node(NULL), NULL);
+
+	KUNIT_EXPECT_PTR_EQ(test, bus_find_device_by_of_node(&platform_bus_type, NULL), NULL);
+	KUNIT_EXPECT_PTR_EQ(test, bus_find_device_by_fwnode(&platform_bus_type, NULL), NULL);
+	KUNIT_EXPECT_PTR_EQ(test, bus_find_device_by_acpi_dev(&platform_bus_type, NULL), NULL);
+
+	KUNIT_EXPECT_FALSE(test, device_match_of_node(&pdev->dev, NULL));
+	KUNIT_EXPECT_FALSE(test, device_match_fwnode(&pdev->dev, NULL));
+	KUNIT_EXPECT_FALSE(test, device_match_acpi_dev(&pdev->dev, NULL));
+	KUNIT_EXPECT_FALSE(test, device_match_acpi_handle(&pdev->dev, NULL));
+
+	platform_device_unregister(pdev);
+}
+
+static struct kunit_case platform_device_match_tests[] = {
+	KUNIT_CASE(platform_device_find_by_null_test),
+	{}
+};
+
+static struct kunit_suite platform_device_match_test_suite = {
+	.name = "platform-device-match",
+	.test_cases = platform_device_match_tests,
+};
+
+kunit_test_suites(
+	&platform_device_devm_test_suite,
+	&platform_device_match_test_suite,
+);
 
 MODULE_DESCRIPTION("Test module for platform devices");
 MODULE_AUTHOR("Maxime Ripard <mripard@kernel.org>");
-- 
2.47.0.338.g60cca15819-goog

Re: [PATCH v2 3/3] drivers: base: test: Add ...find_device_by...(... NULL) tests

[Maxime Ripard]

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Hi,

On Wed, Dec 11, 2024 at 04:31:41PM -0800, Brian Norris wrote:
> We recently updated these device_match*() (and therefore, various
> *find_device_by*()) functions to return a consistent 'false' value when
> trying to match a NULL handle. Add tests for this.
> 
> This provides regression-testing coverage for the sorts of bugs that
> underly commit 5c8418cf4025 ("PCI/pwrctrl: Unregister platform device
> only if one actually exists").
> 
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
> 
> Changes in v2:
>  * Keep "devm" and "match" tests in separate suites
> 
>  drivers/base/test/platform-device-test.c | 42 +++++++++++++++++++++++-
>  1 file changed, 41 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/test/platform-device-test.c b/drivers/base/test/platform-device-test.c
> index ea05b8785743..c8d4b0a385f2 100644
> --- a/drivers/base/test/platform-device-test.c
> +++ b/drivers/base/test/platform-device-test.c
> @@ -3,6 +3,8 @@
>  #include <kunit/resource.h>
>  
>  #include <linux/device.h>
> +#include <linux/device/bus.h>
> +#include <linux/of_platform.h>
>  #include <linux/platform_device.h>
>  
>  #define DEVICE_NAME "test"
> @@ -217,7 +219,45 @@ static struct kunit_suite platform_device_devm_test_suite = {
>  	.test_cases = platform_device_devm_tests,
>  };
>  
> -kunit_test_suite(platform_device_devm_test_suite);
> +static void platform_device_find_by_null_test(struct kunit *test)
> +{
> +	struct platform_device *pdev;
> +	int ret;
> +
> +	pdev = platform_device_alloc(DEVICE_NAME, PLATFORM_DEVID_NONE);
> +	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
> +
> +	ret = platform_device_add(pdev);
> +	KUNIT_ASSERT_EQ(test, ret, 0);

I *think* you have a bug there: if platform_device_add fails,
KUNIT_ASSERT will stop the test execution and thus you will leak the
platform_device you just allocated.

You need to call platform_device_put in such a case, but if
platform_device_add succeeds then you need to call
platform_device_unregister instead.

It would be better to use kunit_platform_device_alloc and
kunit_platform_device_add that already deal with this.

The rest looks good to me, once fixed:
Reviewed-by: Maxime Ripard <mripard@kernel.org>

Maxime

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Re: [PATCH v2 3/3] drivers: base: test: Add ...find_device_by...(... NULL) tests

[Brian Norris]

Hi Maxime,

On Fri, Dec 13, 2024 at 12:59:57PM +0100, Maxime Ripard wrote:
> On Wed, Dec 11, 2024 at 04:31:41PM -0800, Brian Norris wrote:
> > --- a/drivers/base/test/platform-device-test.c
> > +++ b/drivers/base/test/platform-device-test.c

> > @@ -217,7 +219,45 @@ static struct kunit_suite platform_device_devm_test_suite = {
> >  	.test_cases = platform_device_devm_tests,
> >  };
> >  
> > -kunit_test_suite(platform_device_devm_test_suite);
> > +static void platform_device_find_by_null_test(struct kunit *test)
> > +{
> > +	struct platform_device *pdev;
> > +	int ret;
> > +
> > +	pdev = platform_device_alloc(DEVICE_NAME, PLATFORM_DEVID_NONE);
> > +	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
> > +
> > +	ret = platform_device_add(pdev);
> > +	KUNIT_ASSERT_EQ(test, ret, 0);
> 
> I *think* you have a bug there: if platform_device_add fails,
> KUNIT_ASSERT will stop the test execution and thus you will leak the
> platform_device you just allocated.
> 
> You need to call platform_device_put in such a case, but if
> platform_device_add succeeds then you need to call
> platform_device_unregister instead.

Hehe, well I'm imitating the existing leaks in the other tests in this
file, then ;) But admittedly, those are a little more complex, because
the unregistration is actually part of the test flow.

> It would be better to use kunit_platform_device_alloc and
> kunit_platform_device_add that already deal with this.

Cool, thanks, I'll use those in v3 for my new test.

> The rest looks good to me, once fixed:
> Reviewed-by: Maxime Ripard <mripard@kernel.org>

Thanks for the tips and review.

Brian