Subject: Re: [PATCH v5 07/12] kunit: test: create a single centralized executor for all tests

From: Kees Cook <[email-masked]>
Date: Fri, 26 Jun 2020 14:29:22 -0700

On Fri, Jun 26, 2020 at 02:09:12PM -0700, Brendan Higgins wrote:
> From: Alan Maguire <[email-masked]>
> 
> Add a centralized executor to dispatch tests rather than relying on
> late_initcall to schedule each test suite separately. Centralized
> execution is for built-in tests only; modules will execute tests when
> loaded.
> 
> Signed-off-by: Alan Maguire <[email-masked]>
> Co-developed-by: Iurii Zaikin <[email-masked]>
> Signed-off-by: Iurii Zaikin <[email-masked]>
> Co-developed-by: Brendan Higgins <[email-masked]>
> Signed-off-by: Brendan Higgins <[email-masked]>
> Reviewed-by: Stephen Boyd <[email-masked]>
> ---
>  include/kunit/test.h | 67 +++++++++++++++++++++++++++++---------------
>  lib/kunit/Makefile   |  3 +-
>  lib/kunit/executor.c | 28 ++++++++++++++++++
>  lib/kunit/test.c     |  2 +-
>  4 files changed, 76 insertions(+), 24 deletions(-)
>  create mode 100644 lib/kunit/executor.c
> 
> diff --git a/include/kunit/test.h b/include/kunit/test.h
> index 47e61e1d53370..f3e86c3953a2b 100644
> --- a/include/kunit/test.h
> +++ b/include/kunit/test.h
> @@ -224,7 +224,7 @@ size_t kunit_suite_num_test_cases(struct kunit_suite *suite);
>  unsigned int kunit_test_case_num(struct kunit_suite *suite,
>  				 struct kunit_case *test_case);
>  
> -int __kunit_test_suites_init(struct kunit_suite **suites);
> +int __kunit_test_suites_init(struct kunit_suite * const * const suites);
>  
>  void __kunit_test_suites_exit(struct kunit_suite **suites);
>  
> @@ -237,34 +237,57 @@ void __kunit_test_suites_exit(struct kunit_suite **suites);
>   * Registers @suites_list with the test framework. See &struct kunit_suite for
>   * more information.
>   *
> - * When builtin, KUnit tests are all run as late_initcalls; this means
> - * that they cannot test anything where tests must run at a different init
> - * phase. One significant restriction resulting from this is that KUnit
> - * cannot reliably test anything that is initialize in the late_init phase;
> - * another is that KUnit is useless to test things that need to be run in
> - * an earlier init phase.
> - *
> - * An alternative is to build the tests as a module.  Because modules
> - * do not support multiple late_initcall()s, we need to initialize an
> - * array of suites for a module.
> - *
> - * TODO([email-masked]): Don't run all KUnit tests as
> - * late_initcalls.  I have some future work planned to dispatch all KUnit
> - * tests from the same place, and at the very least to do so after
> - * everything else is definitely initialized.
> + * If a test suite is built-in, module_init() gets translated into
> + * an initcall which we don't want as the idea is that for builtins
> + * the executor will manage execution.  So ensure we do not define
> + * module_{init|exit} functions for the builtin case when registering
> + * suites via kunit_test_suites() below.
>   */
> -#define kunit_test_suites(suites_list...)				\
> -	static struct kunit_suite *suites[] = {suites_list, NULL};	\
> -	static int kunit_test_suites_init(void)				\
> +#ifdef MODULE
> +#define kunit_test_suites_for_module(__suites)				\
> +	static int __init kunit_test_suites_init(void)			\
>  	{								\
> -		return __kunit_test_suites_init(suites);		\
> +		return __kunit_test_suites_init(__suites);		\
>  	}								\
> -	late_initcall(kunit_test_suites_init);				\
> +	module_init(kunit_test_suites_init);				\
> +									\
>  	static void __exit kunit_test_suites_exit(void)			\
>  	{								\
> -		return __kunit_test_suites_exit(suites);		\
> +		return __kunit_test_suites_exit(__suites);		\
>  	}								\
>  	module_exit(kunit_test_suites_exit)
> +#else
> +#define kunit_test_suites_for_module(__suites)
> +#endif /* MODULE */
> +
> +#define __kunit_test_suites(unique_array, unique_suites, ...)		       \
> +	static struct kunit_suite *unique_array[] = { __VA_ARGS__, NULL };     \
> +	kunit_test_suites_for_module(unique_array);			       \
> +	static struct kunit_suite **unique_suites			       \
> +	__used __section(.kunit_test_suites) = unique_array
> +
> +/**
> + * kunit_test_suites() - used to register one or more &struct kunit_suite
> + *			 with KUnit.
> + *
> + * @suites: a statically allocated list of &struct kunit_suite.
> + *
> + * Registers @suites with the test framework. See &struct kunit_suite for
> + * more information.
> + *
> + * When builtin,  KUnit tests are all run via executor; this is done
> + * by placing the array of struct kunit_suite * in the .kunit_test_suites
> + * ELF section.
> + *
> + * An alternative is to build the tests as a module.  Because modules do not
> + * support multiple initcall()s, we need to initialize an array of suites for a
> + * module.
> + *
> + */
> +#define kunit_test_suites(...)						\
> +	__kunit_test_suites(__UNIQUE_ID(array),				\
> +			    __UNIQUE_ID(suites),			\
> +			    __VA_ARGS__)
>  
>  #define kunit_test_suite(suite)	kunit_test_suites(&suite)
>  
> diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile
> index 724b94311ca36..c49f4ffb6273a 100644
> --- a/lib/kunit/Makefile
> +++ b/lib/kunit/Makefile
> @@ -3,7 +3,8 @@ obj-$(CONFIG_KUNIT) +=			kunit.o
>  kunit-objs +=				test.o \
>  					string-stream.o \
>  					assert.o \
> -					try-catch.o
> +					try-catch.o \
> +					executor.o
>  
>  ifeq ($(CONFIG_KUNIT_DEBUGFS),y)
>  kunit-objs +=				debugfs.o
> diff --git a/lib/kunit/executor.c b/lib/kunit/executor.c
> new file mode 100644
> index 0000000000000..7015e7328dce7
> --- /dev/null
> +++ b/lib/kunit/executor.c
> @@ -0,0 +1,28 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <kunit/test.h>
> +
> +/*
> + * These symbols point to the .kunit_test_suites section and are defined in
> + * include/asm-generic/vmlinux.lds.h, and consequently must be extern.
> + */
> +extern struct kunit_suite * const * const __kunit_suites_start[];
> +extern struct kunit_suite * const * const __kunit_suites_end[];

I would expect these to be in include/asm-generic/sections.h but I guess
it's not required.

Reviewed-by: Kees Cook <[email-masked]>

-- 
Kees Cook