On Tue, 12 Aug 2025 at 06:17, Marie Zhussupova marievic@google.com wrote:

Currently, KUnit parameterized tests lack a mechanism to share resources across parameter runs because the same `struct kunit` instance is cleaned up and reused for each run.

This patch introduces parameterized test context, enabling test users to share resources between parameter runs. It also allows setting up resources that need to be available for all parameter runs only once, which is helpful in cases where setup is expensive.

To establish a parameterized test context, this patch adds a parent pointer field to `struct kunit`. This allows resources added to the parent `struct kunit` to be shared and accessible across all parameter runs.

In kunit_run_tests(), the default `struct kunit` created is now designated to act as the parameterized test context whenever a test is parameterized.

Subsequently, a new `struct kunit` is made for each parameter run, and its parent pointer is set to the `struct kunit` that holds the parameterized test context.

Signed-off-by: Marie Zhussupova marievic@google.com

Thanks, this looks good to me.

Reviewed-by: David Gow davidgow@google.com

Cheers, -- David

Changes in v2:

• Descriptions of the parent pointer in `struct kunit` were changed to be more general, as it could be used to share resources not only between parameter runs but also between test cases in the future.
• When printing parameter descriptions using test.param_index was changed to param_test.param_index.
• kunit_cleanup(&test) in kunit_run_tests() was moved inside the parameterized test check.
• The comments and the commit message were changed to reflect the parameterized testing terminology. See the patch series cover letter change log for the definitions.

---

include/kunit/test.h | 8 ++++++-- lib/kunit/test.c | 34 ++++++++++++++++++++-------------- 2 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/include/kunit/test.h b/include/kunit/test.h index 39c768f87dc9..b47b9a3102f3 100644 --- a/include/kunit/test.h +++ b/include/kunit/test.h @@ -268,14 +268,18 @@ struct kunit_suite_set {

• @priv: for user to store arbitrary data. Commonly used to pass data

•   created in the init function (see &struct kunit_suite).
  

• • @parent: reference to the parent context of type struct kunit that can

• •     be used for storing shared resources.
    

  • 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 one exception is @priv which can be
• • used by the test writer to store arbitrary data.

• • indirectly via public functions; the two exceptions are @priv and @parent
• • which can be used by the test writer to store arbitrary data and access the
• • parent context, respectively.
  */

struct kunit { void *priv;

•   struct kunit *parent;
  
    /* private: internal use only. */
    const char *name; /* Read only after initialization! */
  

diff --git a/lib/kunit/test.c b/lib/kunit/test.c index f3c6b11f12b8..14a8bd846939 100644 --- a/lib/kunit/test.c +++ b/lib/kunit/test.c @@ -647,6 +647,7 @@ int kunit_run_tests(struct kunit_suite *suite) struct kunit_case *test_case; struct kunit_result_stats suite_stats = { 0 }; struct kunit_result_stats total_stats = { 0 };

•   const void *curr_param;
  
    /* Taint the kernel so we know we've run tests. */
    add_taint(TAINT_TEST, LOCKDEP_STILL_OK);
  

@@ -679,37 +680,42 @@ int kunit_run_tests(struct kunit_suite *suite) } else { /* Get initial param. */ param_desc[0] = '\0';

•                   test.param_value = test_case->generate_params(NULL, param_desc);
  

•                   /* TODO: Make generate_params try-catch */
  

•                   curr_param = test_case->generate_params(NULL, param_desc);
                    test_case->status = KUNIT_SKIPPED;
                    kunit_log(KERN_INFO, &test, KUNIT_SUBTEST_INDENT KUNIT_SUBTEST_INDENT
                              "KTAP version 1\n");
                    kunit_log(KERN_INFO, &test, KUNIT_SUBTEST_INDENT KUNIT_SUBTEST_INDENT
                              "# Subtest: %s", test_case->name);
  
  

•                   while (test.param_value) {
  

•                           kunit_run_case_catch_errors(suite, test_case, &test);
  

•                   while (curr_param) {
  

•                           struct kunit param_test = {
  

•                                   .param_value = curr_param,
  

•                                   .param_index = ++test.param_index,
  

•                                   .parent = &test,
  

•                           };
  

•                           kunit_init_test(&param_test, test_case->name, test_case->log);
  

•                           kunit_run_case_catch_errors(suite, test_case, &param_test);
  
                            if (param_desc[0] == '\0') {
                                    snprintf(param_desc, sizeof(param_desc),
  

•                                            "param-%d", test.param_index);
  

•                                            "param-%d", param_test.param_index);
                            }
  
  

•                           kunit_print_ok_not_ok(&test, KUNIT_LEVEL_CASE_PARAM,
  

•                                                 test.status,
  

•                                                 test.param_index + 1,
  

•                           kunit_print_ok_not_ok(&param_test, KUNIT_LEVEL_CASE_PARAM,
  

•                                                 param_test.status,
  

•                                                 param_test.param_index,
                                                  param_desc,
  

•                                                 test.status_comment);
  

•                                                 param_test.status_comment);
  
  

•                           kunit_update_stats(&param_stats, test.status);
  

•                           kunit_update_stats(&param_stats, param_test.status);
  
                            /* Get next param. */
                            param_desc[0] = '\0';
  

•                           test.param_value = test_case->generate_params(test.param_value, param_desc);
  

•                           test.param_index++;
  

•                           test.status = KUNIT_SUCCESS;
  

•                           test.status_comment[0] = '\0';
  

•                           test.priv = NULL;
  

•                           curr_param = test_case->generate_params(curr_param, param_desc);
                    }
  

•                   /* TODO: Put this kunit_cleanup into a try-catch. */
  

•                   kunit_cleanup(&test);
            }
  
            kunit_print_attr((void *)test_case, true, KUNIT_LEVEL_CASE);
  

-- 2.51.0.rc0.205.g4a044479a3-goog

On Mon, Aug 11, 2025 at 6:17 PM Marie Zhussupova marievic@google.com wrote:

Add (*param_init) and (*param_exit) function pointers to `struct kunit_case`. Users will be able to set them via the new KUNIT_CASE_PARAM_WITH_INIT() macro.

param_init/exit will be invoked by kunit_run_tests() once before and once after the parameterized test, respectively. They will receive the `struct kunit` that holds the parameterized test context; facilitating init and exit for shared state.

This patch also sets param_init/exit to None in rust/kernel/kunit.rs.

Signed-off-by: Marie Zhussupova marievic@google.com

Changes in v2:

• param init/exit were set to None in rust/kernel/kunit.rs to fix the Rust breakage.
• The name of __kunit_init_parent_test was changed to kunit_init_parent_param_test and its call was changed to happen only if the test is parameterized.
• The param_exit call was also moved inside the check for if the test is parameterized.
• KUNIT_CASE_PARAM_WITH_INIT() macro logic was changed to not automatically set generate_params() to KUnit's built-in generator function. Instead, the test user will be asked to provide it themselves.
• The comments and the commit message were changed to reflect the parameterized testing terminology. See the patch series cover letter change log for the definitions.

Hello!

This patch looks good to me. Thank you for fixing the Rust breakage! I also appreciate the terminology changes here as well.

Reviewed-by: Rae Moar rmoar@google.com

Thanks!

-Rae

---

include/kunit/test.h | 25 +++++++++++++++++++++++++ lib/kunit/test.c | 20 ++++++++++++++++++++ rust/kernel/kunit.rs | 4 ++++ 3 files changed, 49 insertions(+)

diff --git a/include/kunit/test.h b/include/kunit/test.h index b47b9a3102f3..d2e1b986b161 100644 --- a/include/kunit/test.h +++ b/include/kunit/test.h @@ -92,6 +92,8 @@ struct kunit_attributes {

• @name: the name of the test case.
• @generate_params: the generator function for parameterized tests.
• @attr: the attributes associated with the test

• • @param_init: The init function to run before a parameterized test.
• • @param_exit: The exit function to run after a parameterized test.
  • A test case is a function with the signature,
  • ``void (*)(struct kunit *)``

@@ -128,6 +130,8 @@ struct kunit_case { const char *name; const void* (*generate_params)(const void *prev, char *desc); struct kunit_attributes attr;

•   int (*param_init)(struct kunit *test);
  

•   void (*param_exit)(struct kunit *test);
  
    /* private: internal use only. */
    enum kunit_status status;
  

@@ -218,6 +222,27 @@ static inline char *kunit_status_to_ok_not_ok(enum kunit_status status) .generate_params = gen_params, \ .attr = attributes, .module_name = KBUILD_MODNAME}

+/**

• • KUNIT_CASE_PARAM_WITH_INIT - Define a parameterized KUnit test case with custom
• • param_init() and param_exit() functions.
• • @test_name: The function implementing the test case.
• • @gen_params: The function to generate parameters for the test case.
• • @init: A reference to the param_init() function to run before a parameterized test.
• • @exit: A reference to the param_exit() function to run after a parameterized test.
• • Provides the option to register param_init() and param_exit() functions.
• • param_init/exit will be passed the parameterized test context and run once
• • before and once after the parameterized test. The init function can be used
• • to add resources to share between parameter runs, and any other setup logic.
• • The exit function can be used to clean up resources that were not managed by
• • the parameterized test, and any other teardown logic.
• */

+#define KUNIT_CASE_PARAM_WITH_INIT(test_name, gen_params, init, exit) \

•           { .run_case = test_name, .name = #test_name,                    \
  

•             .generate_params = gen_params,                                \
  

•             .param_init = init, .param_exit = exit,                       \
  

•             .module_name = KBUILD_MODNAME}
  

/**

• struct kunit_suite - describes a related collection of &struct kunit_case

diff --git a/lib/kunit/test.c b/lib/kunit/test.c index 14a8bd846939..49a5e6c30c86 100644 --- a/lib/kunit/test.c +++ b/lib/kunit/test.c @@ -641,6 +641,19 @@ static void kunit_accumulate_stats(struct kunit_result_stats *total, total->total += add.total; }

+static void kunit_init_parent_param_test(struct kunit_case *test_case, struct kunit *test) +{

•   if (test_case->param_init) {
  

•           int err = test_case->param_init(test);
  

•           if (err) {
  

•                   kunit_err(test_case, KUNIT_SUBTEST_INDENT KUNIT_SUBTEST_INDENT
  

•                           "# failed to initialize parent parameter test.");
  

•                   test_case->status = KUNIT_FAILURE;
  

•           }
  

•   }
  

+}

int kunit_run_tests(struct kunit_suite *suite) { char param_desc[KUNIT_PARAM_DESC_SIZE]; @@ -678,6 +691,7 @@ int kunit_run_tests(struct kunit_suite *suite) kunit_run_case_catch_errors(suite, test_case, &test); kunit_update_stats(&param_stats, test.status); } else {

•                   kunit_init_parent_param_test(test_case, &test);
                    /* Get initial param. */
                    param_desc[0] = '\0';
                    /* TODO: Make generate_params try-catch */
  

@@ -714,6 +728,12 @@ int kunit_run_tests(struct kunit_suite *suite) param_desc[0] = '\0'; curr_param = test_case->generate_params(curr_param, param_desc); }

•                   /*
  

•                    * TODO: Put into a try catch. Since we don't need suite->exit
  

•                    * for it we can't reuse kunit_try_run_cleanup for this yet.
  

•                    */
  

•                   if (test_case->param_exit)
  

•                           test_case->param_exit(&test);
                    /* TODO: Put this kunit_cleanup into a try-catch. */
                    kunit_cleanup(&test);
            }
  

diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index 4b8cdcb21e77..cda64574b44d 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -207,6 +207,8 @@ pub const fn kunit_case( status: kernel::bindings::kunit_status_KUNIT_SUCCESS, module_name: core::ptr::null_mut(), log: core::ptr::null_mut(),

•    param_init: None,
  

•    param_exit: None,
  

  }

}

@@ -226,6 +228,8 @@ pub const fn kunit_case_null() -> kernel::bindings::kunit_case { status: kernel::bindings::kunit_status_KUNIT_SUCCESS, module_name: core::ptr::null_mut(), log: core::ptr::null_mut(),

•    param_init: None,
  

•    param_exit: None,
  

  }

}

-- 2.51.0.rc0.205.g4a044479a3-goog

On Mon, Aug 11, 2025 at 6:17 PM Marie Zhussupova marievic@google.com wrote:

To enable more complex parameterized testing scenarios, the generate_params() function needs additional context beyond just the previously generated parameter. This patch modifies the generate_params() function signature to include an extra `struct kunit *test` argument, giving test users access to the parameterized test context when generating parameters.

The `struct kunit *test` argument was added as the first parameter to the function signature as it aligns with the convention of other KUnit functions that accept `struct kunit *test` first. This also mirrors the "this" or "self" reference found in object-oriented programming languages.

This patch also modifies xe_pci_live_device_gen_param() in xe_pci.c and nthreads_gen_params() in kcsan_test.c to reflect this signature change.

Signed-off-by: Marie Zhussupova marievic@google.com

Changes in v2:

• generate_params signature changes in xe_pci.c and kcsan_test.c were squashed into a single patch to avoid in-between breakages in the series.
• The comments and the commit message were changed to reflect the parameterized testing terminology. See the patch series cover letter change log for the definitions.

Hi!

Happy to see this patch go through to give generate_params() access to resources and context!

As before, this patch is: Reviewed-by: Rae Moar rmoar@google.com

Thanks!

-Rae

---

drivers/gpu/drm/xe/tests/xe_pci.c | 2 +- include/kunit/test.h | 9 ++++++--- kernel/kcsan/kcsan_test.c | 2 +- lib/kunit/test.c | 5 +++-- 4 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/xe/tests/xe_pci.c b/drivers/gpu/drm/xe/tests/xe_pci.c index 1d3e2e50c355..62c016e84227 100644 --- a/drivers/gpu/drm/xe/tests/xe_pci.c +++ b/drivers/gpu/drm/xe/tests/xe_pci.c @@ -129,7 +129,7 @@ EXPORT_SYMBOL_IF_KUNIT(xe_pci_fake_device_init);

• Return: pointer to the next &struct xe_device ready to be used as a parameter

•     or NULL if there are no more Xe devices on the system.
  

*/ -const void *xe_pci_live_device_gen_param(const void *prev, char *desc) +const void *xe_pci_live_device_gen_param(struct kunit *test, const void *prev, char *desc) { const struct xe_device *xe = prev; struct device *dev = xe ? xe->drm.dev : NULL; diff --git a/include/kunit/test.h b/include/kunit/test.h index d2e1b986b161..b527189d2d1c 100644 --- a/include/kunit/test.h +++ b/include/kunit/test.h @@ -128,7 +128,8 @@ struct kunit_attributes { struct kunit_case { void (*run_case)(struct kunit *test); const char *name;

•   const void* (*generate_params)(const void *prev, char *desc);
  

•   const void* (*generate_params)(struct kunit *test,
  

•                                  const void *prev, char *desc);
    struct kunit_attributes attr;
    int (*param_init)(struct kunit *test);
    void (*param_exit)(struct kunit *test);
  

@@ -1691,7 +1692,8 @@ do { \

• Define function @name_gen_params which uses @array to generate parameters.

*/ #define KUNIT_ARRAY_PARAM(name, array, get_desc) \

•   static const void *name##_gen_params(const void *prev, char *desc)                      \
  

•   static const void *name##_gen_params(struct kunit *test,                                \
  

•                                        const void *prev, char *desc)                      \
    {                                                                                       \
            typeof((array)[0]) *__next = prev ? ((typeof(__next)) prev) + 1 : (array);      \
            if (__next - (array) < ARRAY_SIZE((array))) {                                   \
  

@@ -1712,7 +1714,8 @@ do { \

• Define function @name_gen_params which uses @array to generate parameters.

*/ #define KUNIT_ARRAY_PARAM_DESC(name, array, desc_member) \

•   static const void *name##_gen_params(const void *prev, char *desc)                      \
  

•   static const void *name##_gen_params(struct kunit *test,                                \
  

•                                        const void *prev, char *desc)                      \
    {                                                                                       \
            typeof((array)[0]) *__next = prev ? ((typeof(__next)) prev) + 1 : (array);      \
            if (__next - (array) < ARRAY_SIZE((array))) {                                   \
  

diff --git a/kernel/kcsan/kcsan_test.c b/kernel/kcsan/kcsan_test.c index c2871180edcc..fc76648525ac 100644 --- a/kernel/kcsan/kcsan_test.c +++ b/kernel/kcsan/kcsan_test.c @@ -1383,7 +1383,7 @@ static void test_atomic_builtins_missing_barrier(struct kunit *test)

• The thread counts are chosen to cover potentially interesting boundaries and
• corner cases (2 to 5), and then stress the system with larger counts.

*/ -static const void *nthreads_gen_params(const void *prev, char *desc) +static const void *nthreads_gen_params(struct kunit *test, const void *prev, char *desc) { long nthreads = (long)prev;

diff --git a/lib/kunit/test.c b/lib/kunit/test.c index 49a5e6c30c86..01b20702a5a2 100644 --- a/lib/kunit/test.c +++ b/lib/kunit/test.c @@ -695,7 +695,7 @@ int kunit_run_tests(struct kunit_suite *suite) /* Get initial param. */ param_desc[0] = '\0'; /* TODO: Make generate_params try-catch */

•                   curr_param = test_case->generate_params(NULL, param_desc);
  

•                   curr_param = test_case->generate_params(&test, NULL, param_desc);
                    test_case->status = KUNIT_SKIPPED;
                    kunit_log(KERN_INFO, &test, KUNIT_SUBTEST_INDENT KUNIT_SUBTEST_INDENT
                              "KTAP version 1\n");
  

@@ -726,7 +726,8 @@ int kunit_run_tests(struct kunit_suite *suite)

                            /* Get next param. */
                            param_desc[0] = '\0';

•                           curr_param = test_case->generate_params(curr_param, param_desc);
  

•                           curr_param = test_case->generate_params(&test, curr_param,
  

•                                                                   param_desc);
                    }
                    /*
                     * TODO: Put into a try catch. Since we don't need suite->exit
  

-- 2.51.0.rc0.205.g4a044479a3-goog

On Tue, 12 Aug 2025 at 06:17, Marie Zhussupova marievic@google.com wrote:

To enable more complex parameterized testing scenarios, the generate_params() function needs additional context beyond just the previously generated parameter. This patch modifies the generate_params() function signature to include an extra `struct kunit *test` argument, giving test users access to the parameterized test context when generating parameters.

The `struct kunit *test` argument was added as the first parameter to the function signature as it aligns with the convention of other KUnit functions that accept `struct kunit *test` first. This also mirrors the "this" or "self" reference found in object-oriented programming languages.

This patch also modifies xe_pci_live_device_gen_param() in xe_pci.c and nthreads_gen_params() in kcsan_test.c to reflect this signature change.

Signed-off-by: Marie Zhussupova marievic@google.com

Looks great, thanks!

Reviewed-by: David Gow davidgow@google.com

Cheers, -- David

Changes in v2:

• generate_params signature changes in xe_pci.c and kcsan_test.c were squashed into a single patch to avoid in-between breakages in the series.
• The comments and the commit message were changed to reflect the parameterized testing terminology. See the patch series cover letter change log for the definitions.

---

drivers/gpu/drm/xe/tests/xe_pci.c | 2 +- include/kunit/test.h | 9 ++++++--- kernel/kcsan/kcsan_test.c | 2 +- lib/kunit/test.c | 5 +++-- 4 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/xe/tests/xe_pci.c b/drivers/gpu/drm/xe/tests/xe_pci.c index 1d3e2e50c355..62c016e84227 100644 --- a/drivers/gpu/drm/xe/tests/xe_pci.c +++ b/drivers/gpu/drm/xe/tests/xe_pci.c @@ -129,7 +129,7 @@ EXPORT_SYMBOL_IF_KUNIT(xe_pci_fake_device_init);

• Return: pointer to the next &struct xe_device ready to be used as a parameter

•     or NULL if there are no more Xe devices on the system.
  

*/ -const void *xe_pci_live_device_gen_param(const void *prev, char *desc) +const void *xe_pci_live_device_gen_param(struct kunit *test, const void *prev, char *desc) { const struct xe_device *xe = prev; struct device *dev = xe ? xe->drm.dev : NULL; diff --git a/include/kunit/test.h b/include/kunit/test.h index d2e1b986b161..b527189d2d1c 100644 --- a/include/kunit/test.h +++ b/include/kunit/test.h @@ -128,7 +128,8 @@ struct kunit_attributes { struct kunit_case { void (*run_case)(struct kunit *test); const char *name;

•   const void* (*generate_params)(const void *prev, char *desc);
  

•   const void* (*generate_params)(struct kunit *test,
  

•                                  const void *prev, char *desc);
    struct kunit_attributes attr;
    int (*param_init)(struct kunit *test);
    void (*param_exit)(struct kunit *test);
  

@@ -1691,7 +1692,8 @@ do { \

• Define function @name_gen_params which uses @array to generate parameters.

*/ #define KUNIT_ARRAY_PARAM(name, array, get_desc) \

•   static const void *name##_gen_params(const void *prev, char *desc)                      \
  

•   static const void *name##_gen_params(struct kunit *test,                                \
  

•                                        const void *prev, char *desc)                      \
    {                                                                                       \
            typeof((array)[0]) *__next = prev ? ((typeof(__next)) prev) + 1 : (array);      \
            if (__next - (array) < ARRAY_SIZE((array))) {                                   \
  

@@ -1712,7 +1714,8 @@ do { \

• Define function @name_gen_params which uses @array to generate parameters.

*/ #define KUNIT_ARRAY_PARAM_DESC(name, array, desc_member) \

•   static const void *name##_gen_params(const void *prev, char *desc)                      \
  

•   static const void *name##_gen_params(struct kunit *test,                                \
  

•                                        const void *prev, char *desc)                      \
    {                                                                                       \
            typeof((array)[0]) *__next = prev ? ((typeof(__next)) prev) + 1 : (array);      \
            if (__next - (array) < ARRAY_SIZE((array))) {                                   \
  

diff --git a/kernel/kcsan/kcsan_test.c b/kernel/kcsan/kcsan_test.c index c2871180edcc..fc76648525ac 100644 --- a/kernel/kcsan/kcsan_test.c +++ b/kernel/kcsan/kcsan_test.c @@ -1383,7 +1383,7 @@ static void test_atomic_builtins_missing_barrier(struct kunit *test)

• The thread counts are chosen to cover potentially interesting boundaries and
• corner cases (2 to 5), and then stress the system with larger counts.

*/ -static const void *nthreads_gen_params(const void *prev, char *desc) +static const void *nthreads_gen_params(struct kunit *test, const void *prev, char *desc) { long nthreads = (long)prev;

diff --git a/lib/kunit/test.c b/lib/kunit/test.c index 49a5e6c30c86..01b20702a5a2 100644 --- a/lib/kunit/test.c +++ b/lib/kunit/test.c @@ -695,7 +695,7 @@ int kunit_run_tests(struct kunit_suite *suite) /* Get initial param. */ param_desc[0] = '\0'; /* TODO: Make generate_params try-catch */

•                   curr_param = test_case->generate_params(NULL, param_desc);
  

•                   curr_param = test_case->generate_params(&test, NULL, param_desc);
                    test_case->status = KUNIT_SKIPPED;
                    kunit_log(KERN_INFO, &test, KUNIT_SUBTEST_INDENT KUNIT_SUBTEST_INDENT
                              "KTAP version 1\n");
  

@@ -726,7 +726,8 @@ int kunit_run_tests(struct kunit_suite *suite)

                            /* Get next param. */
                            param_desc[0] = '\0';

•                           curr_param = test_case->generate_params(curr_param, param_desc);
  

•                           curr_param = test_case->generate_params(&test, curr_param,
  

•                                                                   param_desc);
                    }
                    /*
                     * TODO: Put into a try catch. Since we don't need suite->exit
  

-- 2.51.0.rc0.205.g4a044479a3-goog

On Mon, Aug 11, 2025 at 6:17 PM Marie Zhussupova marievic@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 a pre-defined static array and passing the created *_gen_params() to KUNIT_CASE_PARAM().

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_array` 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_array` field can be populated by calling the new kunit_register_params_array() macro from within a param_init() function. This will register the array as part of the parameterized test context. The user will then need to pass kunit_array_gen_params() to the KUNIT_CASE_PARAM_WITH_INIT() macro as the generator function, if not providing their own. kunit_array_gen_params() is a KUnit helper that will use the registered array to generate parameters.

The arrays passed to KUNIT_ARRAY_PARAM(,DESC) will also be registered to the parameterized test context for consistency as well as for higher availability of the parameter count that will be used for outputting a KTAP test plan for a parameterized test.

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@google.com

Hello!

Thanks for all your effort in updating this patch series. It is looking really good. I think I am happy with this patch as is but I do have a comment below.

Thanks! -Rae

---

Changes in v2:

• If the parameter count is available for a parameterized test, the kunit_run_tests() function will now output the KTAP test plan for it.
• The name of the struct kunit_params field in struct kunit was changed from params_data to params_array. This name change better reflects its purpose, which is to encapsulate both the parameter array and its associated metadata.
• The name of `kunit_get_next_param_and_desc` was changed to `kunit_array_gen_params` to make it simpler and to better fit its purpose of being KUnit's built-in generator function that uses arrays to generate parameters.
• The signature of get_description() in `struct params_array` was changed to accept the parameterized test context, as well. This way test users can potentially use information available in the parameterized test context, such as the parameterized test name for setting the parameter descriptions.
• The type of `num_params` in `struct params_array` was changed from int to size_t for better handling of the array size.
• The name of __kunit_init_params() was changed to be kunit_init_params(). Logic that sets the get_description() function pointer to NULL was also added in there.
• `kunit_array_gen_params` is now exported to make it available to use with modules.
• Instead of allowing NULL to be passed in as the parameter generator function in the KUNIT_CASE_PARAM_WITH_INIT macro, users will now be asked to provide `kunit_array_gen_params` as the generator function. This will ensure that a parameterized test remains defined by the existence of a parameter generation function.
• KUNIT_ARRAY_PARAM(,DESC) will now additionally register the passed in array in struct kunit_params. This will make things more consistent i.e. if a parameter array is available then the struct kunit_params field in parent struct kunit is populated. Additionally, this will increase the availability of the KTAP test plan.
• The comments and the commit message were changed to reflect the parameterized testing terminology. See the patch series cover letter change log for the definitions.

---

include/kunit/test.h | 65 ++++++++++++++++++++++++++++++++++++++++---- lib/kunit/test.c | 30 ++++++++++++++++++++ 2 files changed, 89 insertions(+), 6 deletions(-)

diff --git a/include/kunit/test.h b/include/kunit/test.h index b527189d2d1c..8cc9614a88d5 100644 --- a/include/kunit/test.h +++ b/include/kunit/test.h @@ -234,9 +234,13 @@ static inline char *kunit_status_to_ok_not_ok(enum kunit_status status)

• Provides the option to register param_init() and param_exit() functions.
• param_init/exit will be passed the parameterized test context and run once
• before and once after the parameterized test. The init function can be used

• • to add resources to share between parameter runs, and any other setup logic.
• • The exit function can be used to clean up resources that were not managed by
• • the parameterized test, and any other teardown logic.

• • to add resources to share between parameter runs, pass parameter arrays,
• • and any other setup logic. The exit function can be used to clean up resources
• • that were not managed by the parameterized test, and any other teardown logic.
• • Note: If you are registering a parameter array in param_init() with
• • kunit_register_param_array() then you need to pass kunit_array_gen_params()
• • to this as the generator function.
  */

#define KUNIT_CASE_PARAM_WITH_INIT(test_name, gen_params, init, exit) \ { .run_case = test_name, .name = #test_name, \ @@ -289,6 +293,20 @@ 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 a parameterized test. This
  

•    * is NULL if a parameter array wasn't directly passed to the
  

•    * parameterized test context struct kunit via kunit_register_params_array().
  

•    */
  

•   const void *params;
  

•   /* Reference to a function that gets the description of a parameter. */
  

•   void (*get_description)(struct kunit *test, const void *param, char *desc);
  

I'm a little bit uncertain whether I like this change to get_description. I don't like that the function signature for a get_description function is different now between kunit_register_params_array and the KUNIT_ARRAY_PARAM_DESC. I think I would prefer it as it was before.

However, I do still like the idea of users being able to set struct kunit test->name for each param run as the test name but that would require some reworking because the struct kunit test that is passed into generate_params and get_description is the parent test I believe rather than each individual param run. So I think I might prefer it as it was.

•   size_t num_params;
  

•   size_t elem_size;
  

+};

/**

• struct kunit - represents a running instance of a test.

@@ -296,16 +314,18 @@ struct kunit_suite_set {

•   created in the init function (see &struct kunit_suite).
  

• @parent: reference to the parent context of type struct kunit that can

•     be used for storing shared resources.
  

• • @params_array: for storing 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 and access the
• • parent context, respectively.

• • indirectly via public functions; the exceptions are @priv, @parent and
• • @params_array which can be used by the test writer to store arbitrary data,
• • access the parent context, and to store the parameter array, respectively.
  */

struct kunit { void *priv; struct kunit *parent;

•   struct kunit_params params_array;
  
    /* private: internal use only. */
    const char *name; /* Read only after initialization! */
  

@@ -376,6 +396,8 @@ 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_array_gen_params(struct kunit *test, const void *prev, char *desc);

#if IS_BUILTIN(CONFIG_KUNIT) int kunit_run_all_tests(void); #else @@ -1696,6 +1718,8 @@ do { \ const void *prev, char *desc) \ { \ typeof((array)[0]) *__next = prev ? ((typeof(__next)) prev) + 1 : (array); \

•           if (!prev)                                                                      \
  

•                   kunit_register_params_array(test, array, ARRAY_SIZE(array), NULL);      \
            if (__next - (array) < ARRAY_SIZE((array))) {                                   \
                    void (*__get_desc)(typeof(__next), char *) = get_desc;                  \
                    if (__get_desc)                                                         \
  

@@ -1718,6 +1742,8 @@ do { \ const void *prev, char *desc) \ { \ typeof((array)[0]) *__next = prev ? ((typeof(__next)) prev) + 1 : (array); \

•           if (!prev)                                                                      \
  

•                   kunit_register_params_array(test, array, ARRAY_SIZE(array), NULL);      \
            if (__next - (array) < ARRAY_SIZE((array))) {                                   \
                    strscpy(desc, __next->desc_member, KUNIT_PARAM_DESC_SIZE);              \
                    return __next;                                                          \
  

@@ -1725,6 +1751,33 @@ do { \ return NULL; \ }

+/**

• • kunit_register_params_array() - Register parameter array for a KUnit test.
• • @test: The KUnit test structure to which parameters will be added.
• • @array: An array of test parameters.
• • @param_count: Number of parameters.
• • @get_desc: Function that generates a string description for a given parameter
• • element.
• • This macro initializes the @test's parameter array data, storing information
• • including the parameter array, its count, the element size, and the parameter
• • description function within `test->params_array`.
• • Note: If using this macro in param_init(), kunit_array_gen_params()
• • will then need to be manually provided as the parameter generator function to
• • KUNIT_CASE_PARAM_WITH_INIT(). kunit_array_gen_params() is a KUnit
• • function that uses the registered array to generate parameters
• */

+#define kunit_register_params_array(test, array, param_count, get_desc) \

•   do {                                                                                    \
  

•           struct kunit *_test = (test);                                                   \
  

•           const typeof((array)[0]) * _params_ptr = &(array)[0];                           \
  

•           _test->params_array.params = _params_ptr;                                       \
  

•           _test->params_array.num_params = (param_count);                                 \
  

•           _test->params_array.elem_size = sizeof(*_params_ptr);                           \
  

•           _test->params_array.get_description = (get_desc);                               \
  

•   } while (0)
  

// TODO(dlatypov@google.com): consider eventually migrating users to explicitly // include resource.h themselves if they need it. #include <kunit/resource.h> diff --git a/lib/kunit/test.c b/lib/kunit/test.c index 01b20702a5a2..cbde238ff334 100644 --- a/lib/kunit/test.c +++ b/lib/kunit/test.c @@ -337,6 +337,14 @@ void __kunit_do_failed_assertion(struct kunit *test, } EXPORT_SYMBOL_GPL(__kunit_do_failed_assertion);

+static void kunit_init_params(struct kunit *test) +{

•   test->params_array.params = NULL;
  

•   test->params_array.get_description = NULL;
  

•   test->params_array.num_params = 0;
  

•   test->params_array.elem_size = 0;
  

+}

void kunit_init_test(struct kunit *test, const char *name, struct string_stream *log) { spin_lock_init(&test->lock); @@ -347,6 +355,7 @@ void kunit_init_test(struct kunit *test, const char *name, struct string_stream string_stream_clear(log); test->status = KUNIT_SUCCESS; test->status_comment[0] = '\0';

•   kunit_init_params(test);
  

} EXPORT_SYMBOL_GPL(kunit_init_test);

@@ -641,6 +650,23 @@ static void kunit_accumulate_stats(struct kunit_result_stats *total, total->total += add.total; }

+const void *kunit_array_gen_params(struct kunit *test, const void *prev, char *desc) +{

•   struct kunit_params *params_arr = &test->params_array;
  

•   const void *param;
  

•   if (test->param_index < params_arr->num_params) {
  

•           param = (char *)params_arr->params
  

•                   + test->param_index * params_arr->elem_size;
  

•           if (params_arr->get_description)
  

•                   params_arr->get_description(test, param, desc);
  

•           return param;
  

•   }
  

•   return NULL;
  

+} +EXPORT_SYMBOL_GPL(kunit_array_gen_params);

static void kunit_init_parent_param_test(struct kunit_case *test_case, struct kunit *test) { if (test_case->param_init) { @@ -701,6 +727,10 @@ int kunit_run_tests(struct kunit_suite *suite) "KTAP version 1\n"); kunit_log(KERN_INFO, &test, KUNIT_SUBTEST_INDENT KUNIT_SUBTEST_INDENT "# Subtest: %s", test_case->name);

•                   if (test.params_array.params)
  

•                           kunit_log(KERN_INFO, &test, KUNIT_SUBTEST_INDENT
  

•                                     KUNIT_SUBTEST_INDENT "1..%zd\n",
  

•                                     test.params_array.num_params);
  
                    while (curr_param) {
                            struct kunit param_test = {
  

-- 2.51.0.rc0.205.g4a044479a3-goog

On Tue, 12 Aug 2025 at 06:18, Marie Zhussupova marievic@google.com wrote:

Add example_params_test_with_init() to illustrate how to manage shared resources across a parameterized KUnit test. This example showcases the use of the new param_init() function and its registration to a test using the KUNIT_CASE_PARAM_WITH_INIT() macro.

Additionally, the test demonstrates how to directly pass a parameter array to the parameterized test context via kunit_register_params_array() and leveraging the Resource API for shared resource management.

Signed-off-by: Marie Zhussupova marievic@google.com

This looks fine to me. One note below about one of the comments.

Otherwise, Reviewed-by: David Gow davidgow@google.com

Cheers, -- David

Changes in v2:

• kunit_array_gen_params() is now explicitly passed to KUNIT_CASE_PARAM_WITH_INIT() to be consistent with a parameterized test being defined by the existence of the generate_params() function.
• The comments were edited to be more concise.
• The patch header was changed to reflect that this example test's intent is more aligned with showcasing using the Resource API for shared resource management.
• The comments and the commit message were changed to reflect the parameterized testing terminology. See the patch series cover letter change log for the definitions.

---

lib/kunit/kunit-example-test.c | 118 +++++++++++++++++++++++++++++++++ 1 file changed, 118 insertions(+)

diff --git a/lib/kunit/kunit-example-test.c b/lib/kunit/kunit-example-test.c index 3056d6bc705d..f2819ee58965 100644 --- a/lib/kunit/kunit-example-test.c +++ b/lib/kunit/kunit-example-test.c @@ -277,6 +277,122 @@ static void example_slow_test(struct kunit *test) KUNIT_EXPECT_EQ(test, 1 + 1, 2); }

+/*

• • This custom function allocates memory and sets the information we want
• • stored in the kunit_resource->data field.
• */

+static int example_resource_init(struct kunit_resource *res, void *context) +{

•   int *info = kmalloc(sizeof(*info), GFP_KERNEL);
  

•   if (!info)
  

•           return -ENOMEM;
  

•   *info = *(int *)context;
  

•   res->data = info;
  

•   return 0;
  

+}

+/*

• • This function deallocates memory for the kunit_resource->data field.
• */

+static void example_resource_free(struct kunit_resource *res) +{

•   kfree(res->data);
  

+}

+/*

• • This match function is invoked by kunit_find_resource() to locate
• • a test resource based on certain criteria.
• */

+static bool example_resource_alloc_match(struct kunit *test,

•                                    struct kunit_resource *res,
  

•                                    void *match_data)
  

+{

•   return res->data && res->free == example_resource_free;
  

+}

+/*

• • This is an example of a function that provides a description for each of the
• • parameters in a parameterized test.
• */

+static void example_param_array_get_desc(struct kunit *test, const void *p, char *desc) +{

•   const struct example_param *param = p;
  

•   snprintf(desc, KUNIT_PARAM_DESC_SIZE,
  

•            "example check if %d is less than or equal to 3", param->value);
  

+}

+/*

• • This function gets passed in the parameterized test context i.e. the
• • struct kunit belonging to the parameterized test. You can use this function
• • to add resources you want shared across the whole parameterized test or
• • for additional setup.
• */

+static int example_param_init(struct kunit *test) +{

•   int ctx = 3; /* Data to be stored. */
  

•   size_t arr_size = ARRAY_SIZE(example_params_array);
  

•   /*
  

•    * This allocates a struct kunit_resource, sets its data field to
  

•    * ctx, and adds it to the struct kunit's resources list. Note that
  

•    * this is parameterized test managed. So, it doesn't need to have
  

•    * a custom exit function to deallocation as it will get cleaned up at
  

•    * the end of the parameterized test.
  

•    */
  

•   void *data = kunit_alloc_resource(test, example_resource_init, example_resource_free,
  

•                                     GFP_KERNEL, &ctx);
  

•   if (!data)
  

•           return -ENOMEM;
  

•   /*
  

•    * Pass the parameter array information to the parameterized test context
  

•    * struct kunit. Note that you will need to provide kunit_array_gen_params()
  

•    * as the generator function to KUNIT_CASE_PARAM_WITH_INIT() when registering
  

•    * a parameter array this route.
  

•    *
  

•    * Alternatively, since this is a static array we can also use
  

•    * KUNIT_CASE_PARAM_ARRAY(,DESC) to create  a `*_gen_params()` function
  

•    * and pass that to  KUNIT_CASE_PARAM_WITH_INIT() instead of registering
  

•    * the parameter array here.
  

Maybe we should note that KUNIT_CASE_PARAM_ARRAY{,_DESC}() doesn't let us set an init function, so would be less useful here.

•    */
  

•   kunit_register_params_array(test, example_params_array, arr_size,
  

•                               example_param_array_get_desc);
  

•   return 0;
  

+}

+/*

• • This is an example of a test that uses shared resources available in the
• • parameterized test context.
• */

+static void example_params_test_with_init(struct kunit *test) +{

•   int threshold;
  

•   struct kunit_resource *res;
  

•   const struct example_param *param = test->param_value;
  

•   /* By design, param pointer will not be NULL. */
  

•   KUNIT_ASSERT_NOT_NULL(test, param);
  

•   /*
  

•    * Here we pass test->parent to search for shared resources in the
  

•    * parameterized test context.
  

•    */
  

•   res = kunit_find_resource(test->parent, example_resource_alloc_match, NULL);
  

•   KUNIT_ASSERT_NOT_NULL(test, res);
  

•   /* Since kunit_resource->data is a void pointer we need to typecast it. */
  

•   threshold = *((int *)res->data);
  

•   /* Assert that the parameter is less than or equal to a certain threshold. */
  

•   KUNIT_ASSERT_LE(test, param->value, threshold);
  

•   /* This decreases the reference count after calling kunit_find_resource(). */
  

•   kunit_put_resource(res);
  

+}

/*

• Here we make a list of all the test cases we want to add to the test suite
• below.

@@ -296,6 +412,8 @@ static struct kunit_case example_test_cases[] = { KUNIT_CASE(example_static_stub_using_fn_ptr_test), KUNIT_CASE(example_priv_test), KUNIT_CASE_PARAM(example_params_test, example_gen_params),

•   KUNIT_CASE_PARAM_WITH_INIT(example_params_test_with_init, kunit_array_gen_params,
  

•                              example_param_init, NULL),
    KUNIT_CASE_SLOW(example_slow_test),
    {}
  

};

2.51.0.rc0.205.g4a044479a3-goog

On Mon, Aug 11, 2025 at 6:18 PM Marie Zhussupova marievic@google.com wrote:

Introduce example_params_test_with_init_dynamic_arr(). This new KUnit test demonstrates directly assigning a dynamic parameter array, using the kunit_register_params_array() macro, to a parameterized test context.

It highlights the use of param_init() and param_exit() for initialization and exit of a parameterized test, and their registration to the test case with KUNIT_CASE_PARAM_WITH_INIT().

Signed-off-by: Marie Zhussupova marievic@google.com

Changes in v2:

• kunit_array_gen_params() is now explicitly passed to KUNIT_CASE_PARAM_WITH_INIT() to be consistent with the parameterized test being defined by the existence of the generate_params() function.
• param_init() was changed to output a log at the start of a parameterized test.
• The parameter array was changed to be allocated using kunit_kmalloc_array(), a KUnit memory allocation API, as that would be the preferred/easier method. To still demonstrate a use of param_exit(), it now outputs a log at the end of the parameterized test.
• The comments and the commit message were changed to reflect the parameterized testing terminology. See the patch series cover letter change log for the definitions.

Hi!

I am happy with these changes and I really like this test!

Happy to mark this as: Reviewed-by: Rae Moar rmoar@google.com

Thanks!

-Rae

---

lib/kunit/kunit-example-test.c | 104 +++++++++++++++++++++++++++++++++ 1 file changed, 104 insertions(+)

diff --git a/lib/kunit/kunit-example-test.c b/lib/kunit/kunit-example-test.c index f2819ee58965..ff21511889a4 100644 --- a/lib/kunit/kunit-example-test.c +++ b/lib/kunit/kunit-example-test.c @@ -393,6 +393,107 @@ static void example_params_test_with_init(struct kunit *test) kunit_put_resource(res); }

+/*

• • Helper function to create a parameter array of Fibonacci numbers. This example
• • highlights a parameter generation scenario that is:
• • 1. Not feasible to fully pre-generate at compile time.
• • 2. Challenging to implement with a standard generate_params() function,
• • as it only provides the previous parameter, while Fibonacci requires
• • access to two preceding values for calculation.
• */

+static void *make_fibonacci_params(struct kunit *test, size_t seq_size) +{

•   int *seq;
  

•   if (seq_size <= 0)
  

•           return NULL;
  

•   /*
  

•    * Using kunit_kmalloc_array here ties the lifetime of the array to
  

•    * the parameterized test i.e. it will get automatically cleaned up
  

•    * by KUnit after the parameterized test finishes.
  

•    */
  

•   seq = kunit_kmalloc_array(test, seq_size, sizeof(int), GFP_KERNEL);
  

•   if (!seq)
  

•           return NULL;
  

•   if (seq_size >= 1)
  

•           seq[0] = 0;
  

•   if (seq_size >= 2)
  

•           seq[1] = 1;
  

•   for (int i = 2; i < seq_size; i++)
  

•           seq[i] = seq[i - 1] + seq[i - 2];
  

•   return seq;
  

+}

+/*

• • This is an example of a function that provides a description for each of the
• • parameters.
• */

+static void example_param_dynamic_arr_get_desc(struct kunit *test, const void *p, char *desc) +{

•   const int *fib_num = p;
  

•   snprintf(desc, KUNIT_PARAM_DESC_SIZE, "fibonacci param: %d", *fib_num);
  

+}

+/*

• • Example of a parameterized test param_init() function that registers a dynamic
• • array of parameters.
• */

+static int example_param_init_dynamic_arr(struct kunit *test) +{

•   size_t seq_size;
  

•   int *fibonacci_params;
  

•   kunit_info(test, "initializing parameterized test\n");
  

•   seq_size = 6;
  

•   fibonacci_params = make_fibonacci_params(test, seq_size);
  

•   if (!fibonacci_params)
  

•           return -ENOMEM;
  

•   /*
  

•    * Passes the dynamic parameter array information to the parameterized test
  

•    * context struct kunit. The array and its metadata will be stored in
  

•    * test->parent->params_array. The array itself will be located in
  

•    * params_data.params.
  

•    *
  

•    * Note that you will need to pass kunit_array_gen_params() as the
  

•    * generator function to KUNIT_CASE_PARAM_WITH_INIT() when registering
  

•    * a parameter array this route.
  

•    */
  

•   kunit_register_params_array(test, fibonacci_params, seq_size,
  

•                               example_param_dynamic_arr_get_desc);
  

•   return 0;
  

+}

+/*

• • Example of a parameterized test param_exit() function that outputs a log
• • at the end of the parameterized test. It could also be used for any other
• • teardown logic.
• */

+static void example_param_exit_dynamic_arr(struct kunit *test) +{

•   kunit_info(test, "exiting parameterized test\n");
  

+}

+/*

• • Example of test that uses the registered dynamic array to perform assertions
• • and expectations.
• */

+static void example_params_test_with_init_dynamic_arr(struct kunit *test) +{

•   const int *param = test->param_value;
  

•   int param_val;
  

•   /* By design, param pointer will not be NULL. */
  

•   KUNIT_ASSERT_NOT_NULL(test, param);
  

•   param_val = *param;
  

•   KUNIT_EXPECT_EQ(test, param_val - param_val, 0);
  

+}

/*

• Here we make a list of all the test cases we want to add to the test suite
• below.

@@ -414,6 +515,9 @@ static struct kunit_case example_test_cases[] = { KUNIT_CASE_PARAM(example_params_test, example_gen_params), KUNIT_CASE_PARAM_WITH_INIT(example_params_test_with_init, kunit_array_gen_params, example_param_init, NULL),

•   KUNIT_CASE_PARAM_WITH_INIT(example_params_test_with_init_dynamic_arr,
  

•                              kunit_array_gen_params, example_param_init_dynamic_arr,
  

•                              example_param_exit_dynamic_arr),
    KUNIT_CASE_SLOW(example_slow_test),
    {}
  

};

2.51.0.rc0.205.g4a044479a3-goog

On Tue, 12 Aug 2025 at 06:18, Marie Zhussupova marievic@google.com wrote:

This patch updates the KUnit docs to show how to use the new parameterized test context to share resources between parameter runs. It documents and show examples of different ways the test user can pass parameter arrays to a parameterized test. Finally, it specifies the parameterized testing terminology.

Signed-off-by: Marie Zhussupova marievic@google.com

Thanks very much: I think this is a definite improvement.

I've added some notes below, but I won't be offended if you don't like my suggestions.

Reviewed-by: David Gow davidgow@google.com

Cheers, -- David

Changes in v2:

• The documentation was updated to establish the parameterized testing terminology and reflect all the patch series changes.
• The references to other parts of the KUnit Documentation were not changed from being "Documentation/dev-tools/kunit/api/test.rst" to ":ref:`kunit-resource`" links as originally planned. This is because the existing way shows up as a link to a webpage and it would be hard for people reading the documentation as an .rst file to find the referred section without having the file path.
• The code examples were made more concise.
• Minor edits to titles and formatting.

---

Documentation/dev-tools/kunit/usage.rst | 342 +++++++++++++++++++++++- 1 file changed, 336 insertions(+), 6 deletions(-)

diff --git a/Documentation/dev-tools/kunit/usage.rst b/Documentation/dev-tools/kunit/usage.rst index 066ecda1dd98..b236bb07aaca 100644 --- a/Documentation/dev-tools/kunit/usage.rst +++ b/Documentation/dev-tools/kunit/usage.rst @@ -542,11 +542,29 @@ There is more boilerplate code involved, but it can: Parameterized Testing

-The table-driven testing pattern is common enough that KUnit has special
-support for it.
-
-By reusing the same ``cases`` array from above, we can write the test as a
-"parameterized test" with the following.
+To run a test case against multiple inputs, KUnit provides a parameterized
+testing framework. This feature formalizes and extends the concept of
+table-driven tests discussed previously. A KUnit test is determined to be
+parameterized if a parameter generator function is provided when registering
+the test case.

I'd possibly split the last sentence out into its own paragraph (and maybe expand it a little to mention that this can be either user-written, or a standard KUnit one can be used instead). And maybe mention that it lives in kunit_case->generate_params, and can be set by one of the macros mentioned below.

+To establish the terminology, "parameterized test" refers to the group of all +runs of a single test function with different parameters. "Parameter run" refers +to the execution of the test case function with a single parameter. +"Parameterized test context" is the ``struct kunit`` that holds the +context for the entire parameterized test. Finally, "parameter run context" is +the ``struct kunit`` that holds the context of the individual parameter run.

I think this bit is a little clunky: we could probably simplify it by just saying something like "a 'parameterized test' is a test which is run multple times (once per 'parameter' or 'parameter run'). Each parameter run has both its own independent struct kunit (the "parameter run context") and access to a shared parent struct kunit (the "parameterized test context")."

But it's not wrong as-is, so if you'd rather not change it, that's fine by me.

+Passing Parameters to a Test +^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Annoyingly, this level of heading is pretty indistinguishable from body text in the current kernel theme. Still, it's definitely registered as a heading (and has the anchor link, et al), so it's fine. Maybe something to think about for future theme changes, though.

+There are three ways to provide the parameters to a test:

+Array Parameter Macros:

• KUnit provides special support for the common table-driven testing pattern.
• By applying either ``KUNIT_ARRAY_PARAM`` or ``KUNIT_ARRAY_PARAM_DESC`` to the
• ``cases`` array from the previous section, we can create a parameterized test
• as shown below:

.. code-block:: c

@@ -555,7 +573,7 @@ By reusing the same ``cases`` array from above, we can write the test as a const char *str; const char *sha1; };

•   const struct sha1_test_case cases[] = {
  

•   static const struct sha1_test_case cases[] = {
            {
                    .str = "hello world",
                    .sha1 = "2aae6c35c94fcfb415dbe95f408b9ce91ee846ed",
  

@@ -590,6 +608,318 @@ By reusing the same ``cases`` array from above, we can write the test as a {} };

+Custom Parameter Generator Function:

• The generator function is responsible for generating parameters one-by-one
• and has the following signature:
• ``const void* (*)(struct kunit *test, const void *prev, char *desc)``.
• You can pass the generator function to the ``KUNIT_CASE_PARAM``
• or ``KUNIT_CASE_PARAM_WITH_INIT`` macros.
• The function receives the previously generated parameter as the ``prev`` argument
• (which is ``NULL`` on the first call) and can also access the parameterized
• test context passed as the ``test`` argument. KUnit calls this function
• repeatedly until it returns ``NULL``, which signifies that a parameterized
• test ended.
• Below is an example of how it works:

+.. code-block:: c

•   #define MAX_TEST_BUFFER_SIZE 8
  

•   // Example generator function. It produces a sequence of buffer sizes that
  

•   // are powers of two, starting at 1 (e.g., 1, 2, 4, 8).
  

•   static const void *buffer_size_gen_params(struct kunit *test, const void *prev, char *desc)
  

•   {
  

•           long prev_buffer_size = (long)prev;
  

•           long next_buffer_size = 1; // Start with an initial size of 1.
  

•           // Stop generating parameters if the limit is reached or exceeded.
  

•           if (prev_buffer_size >= MAX_TEST_BUFFER_SIZE)
  

•                   return NULL;
  

•           // For subsequent calls, calculate the next size by doubling the previous one.
  

•           if (prev)
  

•                   next_buffer_size = prev_buffer_size << 1;
  

•           return (void *)next_buffer_size;
  

•   }
  

•   // Simple test to validate that kunit_kzalloc provides zeroed memory.
  

•   static void buffer_zero_test(struct kunit *test)
  

•   {
  

•           long buffer_size = (long)test->param_value;
  

•           // Use kunit_kzalloc to allocate a zero-initialized buffer. This makes the
  

•           // memory "parameter run managed," meaning it's automatically cleaned up at
  

•           // the end of each parameter run.
  

•           int *buf = kunit_kzalloc(test, buffer_size * sizeof(int), GFP_KERNEL);
  

•           // Ensure the allocation was successful.
  

•           KUNIT_ASSERT_NOT_NULL(test, buf);
  

•           // Loop through the buffer and confirm every element is zero.
  

•           for (int i = 0; i < buffer_size; i++)
  

•                   KUNIT_EXPECT_EQ(test, buf[i], 0);
  

•   }
  

•   static struct kunit_case buffer_test_cases[] = {
  

•           KUNIT_CASE_PARAM(buffer_zero_test, buffer_size_gen_params),
  

•           {}
  

•   };
  

+Runtime Parameter Array Registration in the Init Function:

• For more complex scenarios, you can directly register a parameter array
• to the parameterized test context.

Do we need to describe what these "more complex scenarios" are. Additionally, the generator function can also be used for some complex scenarios.

• To do this, you must pass the parameterized test context, the array itself,
• the array size, and a ``get_description()`` function to the
• ``kunit_register_params_array()`` macro. This macro populates
• ``struct kunit_params`` within the parameterized test context, effectively
• storing a parameter array object. The ``get_description()`` function will
• be used for populating parameter descriptions and has the following signature:
• ``void (*)(struct kunit *test, const void *param, char *desc)``. Note that it
• also has access to the parameterized test context.

•  .. important::
  

•     When using this way to register a parameter array, you will need to
  

•     manually pass ``kunit_array_gen_params()`` as the generator function to
  

•     ``KUNIT_CASE_PARAM_WITH_INIT``. ``kunit_array_gen_params()`` is a KUnit
  

•     helper that will use the registered array to generate the parameters.
  

•    If needed, instead of passing the KUnit helper, you can also pass your
  

•    own custom generator function that utilizes the parameter array. To
  

•    access the parameter array from within the parameter generator
  

•    function use ``test->params_array.params``.
  

• The ``kunit_register_params_array()`` macro should be called within a
• ``param_init()`` function that initializes the parameterized test and has
• the following signature ``int (*)(struct kunit *test)``. For a detailed
• explanation of this mechanism please refer to the "Adding Shared Resources"
• section that is after this one. This method supports registering both
• dynamically built and static parameter arrays.
• The code snippet below shows the ``example_param_init_dynamic_arr`` test that
• utilizes ``make_fibonacci_params()`` to create a dynamic array, which is then
• registered using ``kunit_register_params_array()``. To see the full code
• please refer to lib/kunit/kunit-example-test.c starting at line 396.

You should avoid putting a line number here, as it will quickly get out of date. Maybe just mention "A more complete example lives in lib/kunit/kunit-example-test.c", possibly with the test name instead ("example_params_test_with_init_dynamic_arr").

+.. code-block:: c

•   /*
  

•   * Example of a parameterized test param_init() function that registers a dynamic
  

•   * array of parameters.
  

•   */
  

•   static int example_param_init_dynamic_arr(struct kunit *test)
  

•   {
  

•           size_t seq_size;
  

•           int *fibonacci_params;
  

•           kunit_info(test, "initializing parameterized test\n");
  

•           seq_size = 6;
  

•           fibonacci_params = make_fibonacci_params(test, seq_size);
  

•           if (!fibonacci_params)
  

•                   return -ENOMEM;
  

•           /*
  

•           * Passes the dynamic parameter array information to the parameterized test
  

•           * context struct kunit. The array and its metadata will be stored in
  

•           * test->parent->params_array. The array itself will be located in
  

•           * params_data.params.
  

•           */
  

•           kunit_register_params_array(test, fibonacci_params, seq_size,
  

•                                   example_param_dynamic_arr_get_desc);
  

•           return 0;
  

•   }
  

•   static struct kunit_case example_test_cases[] = {
  

•           /*
  

•            * Note how we pass kunit_array_gen_params() to use the array we
  

•            * registered in example_param_init_dynamic_arr() to generate
  

•            * parameters.
  

•            */
  

•           KUNIT_CASE_PARAM_WITH_INIT(example_params_test_with_init_dynamic_arr,
  

•                                      kunit_array_gen_params,
  

•                                      example_param_init_dynamic_arr,
  

•                                      example_param_exit_dynamic_arr),
  

•           {}
  

•   };
  

+Adding Shared Resources +^^^^^^^^^^^^^^^^^^^^^^^ +All parameter runs in this framework hold a reference to the parameterized test +context, which can be accessed using the parent ``struct kunit`` pointer. The +parameterized test context is not used to execute any test logic itself; instead, +it serves as a container for shared resources.

+It's possible to add resources to share between parameter runs within a +parameterized test by using ``KUNIT_CASE_PARAM_WITH_INIT``, to which you pass +custom ``param_init()`` and ``param_exit()`` functions. These functions run once +before and once after the parameterized test, respectively.

+The ``param_init()`` function, with the signature ``int (*)(struct kunit *test)``, +can be used for adding resources to the ``resources`` or ``priv`` fields of +the parameterized test context, registering the parameter array, and any other +initialization logic.

+The ``param_exit()`` function, with the signature ``void (*)(struct kunit *test)``, +can be used to release any resources that were not parameterized test managed (i.e. +not automatically cleaned up after the parameterized test ends) and for any other +exit logic.

+Both ``param_init()`` and ``param_exit()`` are passed the parameterized test +context behind the scenes. However, the test case function receives the parameter +run context. Therefore, to manage and access shared resources from within a test +case function, you must use ``test->parent``.

+For instance, finding a shared resource allocated by the Resource API requires +passing ``test->parent`` to ``kunit_find_resource()``. This principle extends to +all other APIs that might be used in the test case function, including +``kunit_kzalloc()``, ``kunit_kmalloc_array()``, and others (see +Documentation/dev-tools/kunit/api/test.rst and the +Documentation/dev-tools/kunit/api/resource.rst).

+.. note::

• The ``suite->init()`` function, which executes before each parameter run,
• receives the parameter run context. Therefore, any resources set up in
• ``suite->init()`` are cleaned up after each parameter run.

+The code below shows how you can add the shared resources. Note that this code +utilizes the Resource API, which you can read more about here: +Documentation/dev-tools/kunit/api/resource.rst. To see the full version of this +code please refer to lib/kunit/kunit-example-test.c starting at line 280.

+.. code-block:: c

•   static int example_resource_init(struct kunit_resource *res, void *context)
  

•   {
  

•           ... /* Code that allocates memory and stores context in res->data. */
  

•   }
  

•   /* This function deallocates memory for the kunit_resource->data field. */
  

•   static void example_resource_free(struct kunit_resource *res)
  

•   {
  

•           kfree(res->data);
  

•   }
  

•   /* This match function locates a test resource based on defined criteria. */
  

•   static bool example_resource_alloc_match(struct kunit *test, struct kunit_resource *res,
  

•                                            void *match_data)
  

•   {
  

•           return res->data && res->free == example_resource_free;
  

•   }
  

•   /* Function to initialize the parameterized test. */
  

•   static int example_param_init(struct kunit *test)
  

•   {
  

•           int ctx = 3; /* Data to be stored. */
  

•           void *data = kunit_alloc_resource(test, example_resource_init,
  

•                                             example_resource_free,
  

•                                             GFP_KERNEL, &ctx);
  

•           if (!data)
  

•                   return -ENOMEM;
  

•           kunit_register_params_array(test, example_params_array,
  

•                                       ARRAY_SIZE(example_params_array));
  

•           return 0;
  

•   }
  

•   /* Example test that uses shared resources in test->resources. */
  

•   static void example_params_test_with_init(struct kunit *test)
  

•   {
  

•           int threshold;
  

•           const struct example_param *param = test->param_value;
  

•           /*  Here we pass test->parent to access the parameterized test context. */
  

•           struct kunit_resource *res = kunit_find_resource(test->parent,
  

•                                                            example_resource_alloc_match,
  

•                                                            NULL);
  

•           threshold = *((int *)res->data);
  

•           KUNIT_ASSERT_LE(test, param->value, threshold);
  

•           kunit_put_resource(res);
  

•   }
  

•   static struct kunit_case example_test_cases[] = {
  

•           KUNIT_CASE_PARAM_WITH_INIT(example_params_test_with_init, kunit_array_gen_params,
  

•                                      example_param_init, NULL),
  

•           {}
  

•   };
  

+As an alternative to using the KUnit Resource API for sharing resources, you can +place them in ``test->parent->priv``. This serves as a more lightweight method +for resource storage, best for scenarios where complex resource management is +not required.

+As stated previously ``param_init()`` and ``param_exit()`` get the parameterized +test context. So, you can directly use ``test->priv`` within ``param_init/exit`` +to manage shared resources. However, from within the test case function, you must +navigate up to the parent ``struct kunit`` i.e. the parameterized test context. +Therefore, you need to use ``test->parent->priv`` to access those same +resources.

+The resources placed in ``test->parent->priv`` will need to be allocated in +memory to persist across the parameter runs. If memory is allocated using the +KUnit memory allocation APIs (described more in the "Allocating Memory" section +below), you won't need to worry about deallocation. The APIs will make the memory +parameterized test 'managed', ensuring that it will automatically get cleaned up +after the parameterized test concludes.

+The code below demonstrates example usage of the ``priv`` field for shared +resources:

+.. code-block:: c

•   static const struct example_param {
  

•           int value;
  

•   } example_params_array[] = {
  

•           { .value = 3, },
  

•           { .value = 2, },
  

•           { .value = 1, },
  

•           { .value = 0, },
  

•   };
  

•   /* Initialize the parameterized test context. */
  

•   static int example_param_init_priv(struct kunit *test)
  

•   {
  

•           int ctx = 3; /* Data to be stored. */
  

•           int arr_size = ARRAY_SIZE(example_params_array);
  

•           /*
  

•            * Allocate memory using kunit_kzalloc(). Since the `param_init`
  

•            * function receives the parameterized test context, this memory
  

•            * allocation will be scoped to the lifetime of the parameterized test.
  

•            */
  

•           test->priv = kunit_kzalloc(test, sizeof(int), GFP_KERNEL);
  

•           /* Assign the context value to test->priv.*/
  

•           *((int *)test->priv) = ctx;
  

•           /* Register the parameter array. */
  

•           kunit_register_params_array(test, example_params_array, arr_size, NULL);
  

•           return 0;
  

•   }
  

•   static void example_params_test_with_init_priv(struct kunit *test)
  

•   {
  

•           int threshold;
  

•           const struct example_param *param = test->param_value;
  

•           /* By design, test->parent will not be NULL. */
  

•           KUNIT_ASSERT_NOT_NULL(test, test->parent);
  

•           /* Here we use test->parent->priv to access the shared resource. */
  

•           threshold = *(int *)test->parent->priv;
  

•           KUNIT_ASSERT_LE(test, param->value, threshold);
  

•   }
  

•   static struct kunit_case example_tests[] = {
  

•           KUNIT_CASE_PARAM_WITH_INIT(example_params_test_with_init_priv,
  

•                                      kunit_array_gen_params,
  

•                                      example_param_init_priv, NULL),
  

•           {}
  

•   };
  

Allocating Memory

-- 2.51.0.rc0.205.g4a044479a3-goog