[PATCH 6/9] kunit: Enable direct registration of parameter arrays to a KUnit test

[Rae Moar]

On Tue, Jul 29, 2025 at 4:14 PM Rae Moar <rmoar at google.com> wrote:
>
> On Tue, Jul 29, 2025 at 3:37 PM Marie Zhussupova <marievic at google.com> wrote:
> >
> > KUnit parameterized tests currently support two
> > primary methods for getting parameters:
> > 1.  Defining custom logic within a `generate_params`
> >     function.
> > 2.  Using the KUNIT_ARRAY_PARAM and KUNIT_ARRAY_PARAM_DESC
> >     macros with pre-defined static arrays.
> >
> > These methods present limitations when dealing with
> > dynamically generated parameter arrays, or in scenarios
> > where populating parameters sequentially via
> > `generate_params` is inefficient or overly complex.
> >
> > This patch addresses these limitations by adding a new
> > `params_data` field to `struct kunit`, of the type
> > `kunit_params`. The struct `kunit_params` is designed to
> > store the parameter array itself, along with essential metadata
> > including the parameter count, parameter size, and a
> > `get_description` function for providing custom descriptions
> > for individual parameters.
> >
> > The `params_data` field can be populated by calling the new
> > `kunit_register_params_array` macro from within a
> > `param_init` function. By attaching the parameter array
> > directly to the parent kunit test instance, these parameters
> > can be iterated over in kunit_run_tests() behind the scenes.
> >
> > This modification provides greater flexibility to the
> > KUnit framework, allowing testers to easily register and
> > utilize both dynamic and static parameter arrays.
> >
> > Signed-off-by: Marie Zhussupova <marievic at google.com>
> > ---
> >  include/kunit/test.h | 54 ++++++++++++++++++++++++++++++++++++++++----
> >  lib/kunit/test.c     | 26 ++++++++++++++++++++-
> >  2 files changed, 75 insertions(+), 5 deletions(-)
> >
> > diff --git a/include/kunit/test.h b/include/kunit/test.h
> > index 4ba65dc35710..9143f0e22323 100644
> > --- a/include/kunit/test.h
> > +++ b/include/kunit/test.h
> > @@ -245,7 +245,8 @@ static inline char *kunit_status_to_ok_not_ok(enum kunit_status status)
> >   */
> >  #define KUNIT_CASE_PARAM_WITH_INIT(test_name, gen_params, init, exit)          \
> >                 { .run_case = test_name, .name = #test_name,                    \
> > -                 .generate_params = gen_params,                                \
> > +                 .generate_params = (gen_params)                               \
> > +                  ?: kunit_get_next_param_and_desc,                            \
> >                   .param_init = init, .param_exit = exit,                       \
> >                   .module_name = KBUILD_MODNAME}
> >
> > @@ -294,6 +295,21 @@ struct kunit_suite_set {
> >         struct kunit_suite * const *end;
> >  };
> >
> > +/* Stores the pointer to the parameter array and its metadata. */
> > +struct kunit_params {
> > +       /*
> > +        * Reference to the parameter array for the parameterized tests. This
> > +        * is NULL if a parameter array wasn't directly passed to the
> > +        * parent kunit struct via the kunit_register_params_array macro.
> > +        */
> > +       const void *params;
> > +       /* Reference to a function that gets the description of a parameter. */
> > +       void (*get_description)(const void *param, char *desc);
> > +
> > +       int num_params;
> > +       size_t elem_size;
> > +};
> > +
> >  /**
> >   * struct kunit - represents a running instance of a test.
> >   *
> > @@ -302,12 +318,14 @@ struct kunit_suite_set {
> >   * @parent: for user to store data that they want to shared across
> >   *         parameterized tests. Typically, the data is provided in
> >   *         the param_init function (see &struct kunit_case).
> > + * @params_data: for users to directly store the parameter array.
> >   *
> >   * Used to store information about the current context under which the test
> >   * is running. Most of this data is private and should only be accessed
> > - * indirectly via public functions; the two exceptions are @priv and @parent
> > - * which can be used by the test writer to store arbitrary data or data that is
> > - * available to all parameter test executions, respectively.
> > + * indirectly via public functions. There are three exceptions to this: @priv,
> > + * @parent, and @params_data. These members can be used by the test writer to
> > + * store arbitrary data, data available to all parameter test executions, and
> > + * the parameter array, respectively.
> >   */
> >  struct kunit {
> >         void *priv;
> > @@ -316,6 +334,8 @@ struct kunit {
> >          * during parameterized testing.
> >          */
> >         struct kunit *parent;
> > +       /* Stores the params array and all data related to it. */
> > +       struct kunit_params params_data;
> >
> >         /* private: internal use only. */
> >         const char *name; /* Read only after initialization! */
> > @@ -386,6 +406,8 @@ void kunit_exec_list_tests(struct kunit_suite_set *suite_set, bool include_attr)
> >  struct kunit_suite_set kunit_merge_suite_sets(struct kunit_suite_set init_suite_set,
> >                 struct kunit_suite_set suite_set);
> >
> > +const void *kunit_get_next_param_and_desc(struct kunit *test, const void *prev, char *desc);
>
> Hello!
>
> Thanks for sending out this series! I will do a full review of it. For
> now, I noticed that I get an error when I try to run KUnit tests as
> modules. I get the following error: "ERROR: modpost:
> "kunit_get_next_param_and_desc" [lib/kunit/kunit-example-test.ko]
> undefined!". As a possible fix, I suggest moving the function
> definition into the header file and making it a static inline
> function.
>
> Thanks!
> -Rae
>

Hello! Feel free to also use EXPORT_SYMBOL_GPL(). Either solution
should work here. Thanks!