On Thu, Dec 04, 2025 at 11:10:46AM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
> 
> Some of the recent changes to the kunit framework caused the stack usage
> for kunit_run_tests() to grow higher than most other kernel functions,
> which triggers a warning when CONFIG_FRAME_WARN is set to a relatively
> low value:
> 
> lib/kunit/test.c: In function 'kunit_run_tests':
> lib/kunit/test.c:801:1: error: the frame size of 1312 bytes is larger than 
> 1280 bytes [-Werror=frame-larger-than=]
> 
> Split out the inner loop into a separate function to ensure that each
> function remains under the limit, and pass the kunit_result_stats
> structures by reference to avoid excessive copies.
> 
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> Sending it now as I ran into the build failure while testing 6.18.
> I only build-tested this, so please test it properly before applying.

I just ran this through our CI with no problems.

Tested-by: Carlos Llamas <[email protected]> 

> ---
>  lib/kunit/test.c | 221 ++++++++++++++++++++++++-----------------------
>  1 file changed, 115 insertions(+), 106 deletions(-)
> 
> diff --git a/lib/kunit/test.c b/lib/kunit/test.c
> index 62eb529824c6..c5fce199d880 100644
> --- a/lib/kunit/test.c
> +++ b/lib/kunit/test.c
> @@ -94,7 +94,7 @@ struct kunit_result_stats {
>       unsigned long total;
>  };
>  
> -static bool kunit_should_print_stats(struct kunit_result_stats stats)
> +static bool kunit_should_print_stats(struct kunit_result_stats *stats)
>  {
>       if (kunit_stats_enabled == 0)
>               return false;
> @@ -102,11 +102,11 @@ static bool kunit_should_print_stats(struct 
> kunit_result_stats stats)
>       if (kunit_stats_enabled == 2)
>               return true;
>  
> -     return (stats.total > 1);
> +     return (stats->total > 1);
>  }
>  
>  static void kunit_print_test_stats(struct kunit *test,
> -                                struct kunit_result_stats stats)
> +                                struct kunit_result_stats *stats)
>  {
>       if (!kunit_should_print_stats(stats))
>               return;
> @@ -115,10 +115,10 @@ static void kunit_print_test_stats(struct kunit *test,
>                 KUNIT_SUBTEST_INDENT
>                 "# %s: pass:%lu fail:%lu skip:%lu total:%lu",
>                 test->name,
> -               stats.passed,
> -               stats.failed,
> -               stats.skipped,
> -               stats.total);
> +               stats->passed,
> +               stats->failed,
> +               stats->skipped,
> +               stats->total);
>  }
>  
>  /* Append formatted message to log. */
> @@ -600,26 +600,26 @@ static void kunit_run_case_catch_errors(struct 
> kunit_suite *suite,
>  }
>  
>  static void kunit_print_suite_stats(struct kunit_suite *suite,
> -                                 struct kunit_result_stats suite_stats,
> -                                 struct kunit_result_stats param_stats)
> +                                 struct kunit_result_stats *suite_stats,
> +                                 struct kunit_result_stats *param_stats)
>  {
>       if (kunit_should_print_stats(suite_stats)) {
>               kunit_log(KERN_INFO, suite,
>                         "# %s: pass:%lu fail:%lu skip:%lu total:%lu",
>                         suite->name,
> -                       suite_stats.passed,
> -                       suite_stats.failed,
> -                       suite_stats.skipped,
> -                       suite_stats.total);
> +                       suite_stats->passed,
> +                       suite_stats->failed,
> +                       suite_stats->skipped,
> +                       suite_stats->total);
>       }
>  
>       if (kunit_should_print_stats(param_stats)) {
>               kunit_log(KERN_INFO, suite,
>                         "# Totals: pass:%lu fail:%lu skip:%lu total:%lu",
> -                       param_stats.passed,
> -                       param_stats.failed,
> -                       param_stats.skipped,
> -                       param_stats.total);
> +                       param_stats->passed,
> +                       param_stats->failed,
> +                       param_stats->skipped,
> +                       param_stats->total);
>       }
>  }
>  
> @@ -681,13 +681,106 @@ static void kunit_init_parent_param_test(struct 
> kunit_case *test_case, struct ku
>       }
>  }
>  
> -int kunit_run_tests(struct kunit_suite *suite)
> +static int kunit_run_one_test(struct kunit_suite *suite, struct kunit_case 
> *test_case,
> +                           struct kunit_result_stats *suite_stats,
> +                           struct kunit_result_stats *total_stats)
>  {
> +     struct kunit test = { .param_value = NULL, .param_index = 0 };
> +     struct kunit_result_stats param_stats = { 0 };
>       char param_desc[KUNIT_PARAM_DESC_SIZE];
> +     const void *curr_param;
> +
> +     kunit_init_test(&test, test_case->name, test_case->log);
> +     if (test_case->status == KUNIT_SKIPPED) {
> +             /* Test marked as skip */
> +             test.status = KUNIT_SKIPPED;
> +             kunit_update_stats(&param_stats, test.status);
> +     } else if (!test_case->generate_params) {
> +             /* Non-parameterised test. */
> +             test_case->status = KUNIT_SKIPPED;
> +             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);
> +             if (test_case->status == KUNIT_FAILURE) {
> +                     kunit_update_stats(&param_stats, test.status);
> +                     goto test_case_end;
> +             }
> +             /* Get initial param. */
> +             param_desc[0] = '\0';
> +             /* TODO: Make generate_params try-catch */
> +             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");
> +             kunit_log(KERN_INFO, &test, KUNIT_SUBTEST_INDENT 
> KUNIT_SUBTEST_INDENT
> +                       "# Subtest: %s", test_case->name);
> +             if (test.params_array.params &&
> +                 test_case->generate_params == kunit_array_gen_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 = {
> +                             .param_value = curr_param,
> +                             .param_index = ++test.param_index,
> +                             .parent = &test,
> +                     };
> +                     kunit_init_test(&param_test, test_case->name, NULL);
> +                     param_test.log = 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", param_test.param_index);
> +                     }
> +
> +                     kunit_print_ok_not_ok(&param_test, 
> KUNIT_LEVEL_CASE_PARAM,
> +                                           param_test.status,
> +                                           param_test.param_index,
> +                                           param_desc,
> +                                           param_test.status_comment);
> +
> +                     kunit_update_stats(&param_stats, param_test.status);
> +
> +                     /* Get next param. */
> +                     param_desc[0] = '\0';
> +                     curr_param = test_case->generate_params(&test, 
> 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);
> +     }
> +test_case_end:
> +     kunit_print_attr((void *)test_case, true, KUNIT_LEVEL_CASE);
> +
> +     kunit_print_test_stats(&test, &param_stats);
> +
> +     kunit_print_ok_not_ok(&test, KUNIT_LEVEL_CASE, test_case->status,
> +                           kunit_test_case_num(suite, test_case),
> +                           test_case->name,
> +                           test.status_comment);
> +
> +     kunit_update_stats(suite_stats, test_case->status);
> +     kunit_accumulate_stats(total_stats, param_stats);
> +
> +     return 0;

nit: the return value is always zero and it's not being used either, so
maybe switch to void?

> +}
> +
> +
> +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);
> @@ -703,97 +796,13 @@ int kunit_run_tests(struct kunit_suite *suite)
>  
>       kunit_print_suite_start(suite);
>  
> -     kunit_suite_for_each_test_case(suite, test_case) {
> -             struct kunit test = { .param_value = NULL, .param_index = 0 };
> -             struct kunit_result_stats param_stats = { 0 };
> -
> -             kunit_init_test(&test, test_case->name, test_case->log);
> -             if (test_case->status == KUNIT_SKIPPED) {
> -                     /* Test marked as skip */
> -                     test.status = KUNIT_SKIPPED;
> -                     kunit_update_stats(&param_stats, test.status);
> -             } else if (!test_case->generate_params) {
> -                     /* Non-parameterised test. */
> -                     test_case->status = KUNIT_SKIPPED;
> -                     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);
> -                     if (test_case->status == KUNIT_FAILURE) {
> -                             kunit_update_stats(&param_stats, test.status);
> -                             goto test_case_end;
> -                     }
> -                     /* Get initial param. */
> -                     param_desc[0] = '\0';
> -                     /* TODO: Make generate_params try-catch */
> -                     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");
> -                     kunit_log(KERN_INFO, &test, KUNIT_SUBTEST_INDENT 
> KUNIT_SUBTEST_INDENT
> -                               "# Subtest: %s", test_case->name);
> -                     if (test.params_array.params &&
> -                         test_case->generate_params == 
> kunit_array_gen_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 = {
> -                                     .param_value = curr_param,
> -                                     .param_index = ++test.param_index,
> -                                     .parent = &test,
> -                             };
> -                             kunit_init_test(&param_test, test_case->name, 
> NULL);
> -                             param_test.log = 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", 
> param_test.param_index);
> -                             }
> -
> -                             kunit_print_ok_not_ok(&param_test, 
> KUNIT_LEVEL_CASE_PARAM,
> -                                                   param_test.status,
> -                                                   param_test.param_index,
> -                                                   param_desc,
> -                                                   
> param_test.status_comment);
> -
> -                             kunit_update_stats(&param_stats, 
> param_test.status);
> -
> -                             /* Get next param. */
> -                             param_desc[0] = '\0';
> -                             curr_param = test_case->generate_params(&test, 
> 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);
> -             }
> -test_case_end:
> -             kunit_print_attr((void *)test_case, true, KUNIT_LEVEL_CASE);
> -
> -             kunit_print_test_stats(&test, param_stats);
> -
> -             kunit_print_ok_not_ok(&test, KUNIT_LEVEL_CASE, 
> test_case->status,
> -                                   kunit_test_case_num(suite, test_case),
> -                                   test_case->name,
> -                                   test.status_comment);
> -
> -             kunit_update_stats(&suite_stats, test_case->status);
> -             kunit_accumulate_stats(&total_stats, param_stats);
> -     }
> +     kunit_suite_for_each_test_case(suite, test_case)
> +             kunit_run_one_test(suite, test_case, &suite_stats, 
> &total_stats);
>  
>       if (suite->suite_exit)
>               suite->suite_exit(suite);
>  
> -     kunit_print_suite_stats(suite, suite_stats, total_stats);
> +     kunit_print_suite_stats(suite, &suite_stats, &total_stats);
>  suite_end:
>       kunit_print_suite_end(suite);
>  
> -- 

I don't see any logical changes, everything seems to have been extracted
cleanly into kunit_run_one_test(). So this LGTM, just a minor nit.

--
Carlos LLamas

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