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kunit: Add example parameterized test with shared resource management using the Resource API

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.

Link: https://lore.kernel.org/r/20250826091341.1427123-6-davidgow@google.com
Reviewed-by: Rae Moar <rmoar@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Marie Zhussupova <marievic@google.com>
Signed-off-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

authored by

Marie Zhussupova and committed by
Shuah Khan a03e3caa b820b907

+113
+113
lib/kunit/kunit-example-test.c
··· 278 278 } 279 279 280 280 /* 281 + * This custom function allocates memory and sets the information we want 282 + * stored in the kunit_resource->data field. 283 + */ 284 + static int example_resource_init(struct kunit_resource *res, void *context) 285 + { 286 + int *info = kmalloc(sizeof(*info), GFP_KERNEL); 287 + 288 + if (!info) 289 + return -ENOMEM; 290 + *info = *(int *)context; 291 + res->data = info; 292 + return 0; 293 + } 294 + 295 + /* 296 + * This function deallocates memory for the kunit_resource->data field. 297 + */ 298 + static void example_resource_free(struct kunit_resource *res) 299 + { 300 + kfree(res->data); 301 + } 302 + 303 + /* 304 + * This match function is invoked by kunit_find_resource() to locate 305 + * a test resource based on certain criteria. 306 + */ 307 + static bool example_resource_alloc_match(struct kunit *test, 308 + struct kunit_resource *res, 309 + void *match_data) 310 + { 311 + return res->data && res->free == example_resource_free; 312 + } 313 + 314 + /* 315 + * This is an example of a function that provides a description for each of the 316 + * parameters in a parameterized test. 317 + */ 318 + static void example_param_array_get_desc(struct kunit *test, const void *p, char *desc) 319 + { 320 + const struct example_param *param = p; 321 + 322 + snprintf(desc, KUNIT_PARAM_DESC_SIZE, 323 + "example check if %d is less than or equal to 3", param->value); 324 + } 325 + 326 + /* 327 + * This function gets passed in the parameterized test context i.e. the 328 + * struct kunit belonging to the parameterized test. You can use this function 329 + * to add resources you want shared across the whole parameterized test or 330 + * for additional setup. 331 + */ 332 + static int example_param_init(struct kunit *test) 333 + { 334 + int ctx = 3; /* Data to be stored. */ 335 + size_t arr_size = ARRAY_SIZE(example_params_array); 336 + 337 + /* 338 + * This allocates a struct kunit_resource, sets its data field to 339 + * ctx, and adds it to the struct kunit's resources list. Note that 340 + * this is parameterized test managed. So, it doesn't need to have 341 + * a custom exit function to deallocation as it will get cleaned up at 342 + * the end of the parameterized test. 343 + */ 344 + void *data = kunit_alloc_resource(test, example_resource_init, example_resource_free, 345 + GFP_KERNEL, &ctx); 346 + 347 + if (!data) 348 + return -ENOMEM; 349 + /* 350 + * Pass the parameter array information to the parameterized test context 351 + * struct kunit. Note that you will need to provide kunit_array_gen_params() 352 + * as the generator function to KUNIT_CASE_PARAM_WITH_INIT() when registering 353 + * a parameter array this route. 354 + */ 355 + kunit_register_params_array(test, example_params_array, arr_size, 356 + example_param_array_get_desc); 357 + return 0; 358 + } 359 + 360 + /* 361 + * This is an example of a test that uses shared resources available in the 362 + * parameterized test context. 363 + */ 364 + static void example_params_test_with_init(struct kunit *test) 365 + { 366 + int threshold; 367 + struct kunit_resource *res; 368 + const struct example_param *param = test->param_value; 369 + 370 + /* By design, param pointer will not be NULL. */ 371 + KUNIT_ASSERT_NOT_NULL(test, param); 372 + 373 + /* 374 + * Here we pass test->parent to search for shared resources in the 375 + * parameterized test context. 376 + */ 377 + res = kunit_find_resource(test->parent, example_resource_alloc_match, NULL); 378 + 379 + KUNIT_ASSERT_NOT_NULL(test, res); 380 + 381 + /* Since kunit_resource->data is a void pointer we need to typecast it. */ 382 + threshold = *((int *)res->data); 383 + 384 + /* Assert that the parameter is less than or equal to a certain threshold. */ 385 + KUNIT_ASSERT_LE(test, param->value, threshold); 386 + 387 + /* This decreases the reference count after calling kunit_find_resource(). */ 388 + kunit_put_resource(res); 389 + } 390 + 391 + /* 281 392 * Here we make a list of all the test cases we want to add to the test suite 282 393 * below. 283 394 */ ··· 407 296 KUNIT_CASE(example_static_stub_using_fn_ptr_test), 408 297 KUNIT_CASE(example_priv_test), 409 298 KUNIT_CASE_PARAM(example_params_test, example_gen_params), 299 + KUNIT_CASE_PARAM_WITH_INIT(example_params_test_with_init, kunit_array_gen_params, 300 + example_param_init, NULL), 410 301 KUNIT_CASE_SLOW(example_slow_test), 411 302 {} 412 303 };