Re: [PATCH] of: Skip kunit tests when arm64+ACPI doesn't populate root node

[Mark Rutland <mark.rutland@arm.com>]

On Wed, Oct 09, 2024 at 01:41:31PM -0700, Stephen Boyd wrote:
> A root node is required to apply DT overlays. A root node is usually
> present after commit 7b937cc243e5 ("of: Create of_root if no dtb
> provided by firmware"), except for on arm64 systems booted with ACPI
> tables. In that case, the root node is intentionally not populated
> because it would "allow DT devices to be instantiated atop an ACPI base
> system"[1].
> 
> Introduce an OF function that skips the kunit test if the root node
> isn't populated. Limit the test to when both CONFIG_ARM64 and
> CONFIG_ACPI are set, because otherwise the lack of a root node is a bug.
> Make the function private and take a kunit test parameter so that it
> can't be abused to test for the presence of the root node in non-test
> code.
> 
> Use this function to skip tests that require the root node. Currently
> that's the DT tests and any tests that apply overlays.
> 
> Reported-by: Guenter Roeck <linux@roeck-us.net>
> Closes: https://lore.kernel.org/r/6cd337fb-38f0-41cb-b942-5844b84433db@roeck-us.net
> Link: https://lore.kernel.org/r/Zd4dQpHO7em1ji67@FVFF77S0Q05N.cambridge.arm.com [1]
> Fixes: 893ecc6d2d61 ("of: Add KUnit test to confirm DTB is loaded")
> Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Acked-by: Mark Rutland <mark.rutland@arm.com>

Mark.

> ---
>  drivers/of/of_kunit_helpers.c | 15 +++++++++++++++
>  drivers/of/of_private.h       |  3 +++
>  drivers/of/of_test.c          |  3 +++
>  drivers/of/overlay_test.c     |  3 +++
>  4 files changed, 24 insertions(+)
> 
> diff --git a/drivers/of/of_kunit_helpers.c b/drivers/of/of_kunit_helpers.c
> index 287d6c91bb37..7b3ed5a382aa 100644
> --- a/drivers/of/of_kunit_helpers.c
> +++ b/drivers/of/of_kunit_helpers.c
> @@ -10,6 +10,19 @@
>  #include <kunit/test.h>
>  #include <kunit/resource.h>
>  
> +#include "of_private.h"
> +
> +/**
> + * of_root_kunit_skip() - Skip test if the root node isn't populated
> + * @test: test to skip if the root node isn't populated
> + */
> +void of_root_kunit_skip(struct kunit *test)
> +{
> +	if (IS_ENABLED(CONFIG_ARM64) && IS_ENABLED(CONFIG_ACPI) && !of_root)
> +		kunit_skip(test, "arm64+acpi doesn't populate a root node");
> +}
> +EXPORT_SYMBOL_GPL(of_root_kunit_skip);
> +
>  #if defined(CONFIG_OF_OVERLAY) && defined(CONFIG_OF_EARLY_FLATTREE)
>  
>  static void of_overlay_fdt_apply_kunit_exit(void *ovcs_id)
> @@ -36,6 +49,8 @@ int of_overlay_fdt_apply_kunit(struct kunit *test, void *overlay_fdt,
>  	int ret;
>  	int *copy_id;
>  
> +	of_root_kunit_skip(test);
> +
>  	copy_id = kunit_kmalloc(test, sizeof(*copy_id), GFP_KERNEL);
>  	if (!copy_id)
>  		return -ENOMEM;
> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
> index 04aa2a91f851..c235d6c909a1 100644
> --- a/drivers/of/of_private.h
> +++ b/drivers/of/of_private.h
> @@ -42,6 +42,9 @@ extern raw_spinlock_t devtree_lock;
>  extern struct list_head aliases_lookup;
>  extern struct kset *of_kset;
>  
> +struct kunit;
> +extern void of_root_kunit_skip(struct kunit *test);
> +
>  #if defined(CONFIG_OF_DYNAMIC)
>  extern int of_property_notify(int action, struct device_node *np,
>  			      struct property *prop, struct property *old_prop);
> diff --git a/drivers/of/of_test.c b/drivers/of/of_test.c
> index c85a258bc6ae..b0557ded838f 100644
> --- a/drivers/of/of_test.c
> +++ b/drivers/of/of_test.c
> @@ -7,6 +7,8 @@
>  
>  #include <kunit/test.h>
>  
> +#include "of_private.h"
> +
>  /*
>   * Test that the root node "/" can be found by path.
>   */
> @@ -36,6 +38,7 @@ static struct kunit_case of_dtb_test_cases[] = {
>  
>  static int of_dtb_test_init(struct kunit *test)
>  {
> +	of_root_kunit_skip(test);
>  	if (!IS_ENABLED(CONFIG_OF_EARLY_FLATTREE))
>  		kunit_skip(test, "requires CONFIG_OF_EARLY_FLATTREE");
>  
> diff --git a/drivers/of/overlay_test.c b/drivers/of/overlay_test.c
> index 19a292cdeee3..7cbf9a472111 100644
> --- a/drivers/of/overlay_test.c
> +++ b/drivers/of/overlay_test.c
> @@ -11,6 +11,8 @@
>  #include <kunit/of.h>
>  #include <kunit/test.h>
>  
> +#include "of_private.h"
> +
>  static const char * const kunit_node_name = "kunit-test";
>  static const char * const kunit_compatible = "test,empty";
>  
> @@ -62,6 +64,7 @@ static void of_overlay_apply_kunit_cleanup(struct kunit *test)
>  	struct device *dev;
>  	struct device_node *np;
>  
> +	of_root_kunit_skip(test);
>  	if (!IS_ENABLED(CONFIG_OF_EARLY_FLATTREE))
>  		kunit_skip(test, "requires CONFIG_OF_EARLY_FLATTREE for root node");
>  
> 
> base-commit: 9852d85ec9d492ebef56dc5f229416c925758edc
> -- 
> https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/
> https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git
>