Re: [PATCH v2 1/6] selftests/resctrl: Extend signal handler coverage to unmount on receiving signal

Hi Ilpo,

On 9/15/2023 8:44 AM, Ilpo Järvinen wrote:

Unmounting resctrl FS has been moved into the per test functions in resctrl_tests.c by commit caddc0fbe495 ("selftests/resctrl: Move resctrl FS mount/umount to higher level"). In case a signal (SIGINT, SIGTERM, or SIGHUP) is received, the running selftest is aborted by ctrlc_handler() which then unmounts resctrl fs before exiting. The current section between signal_handler_register() and signal_handler_unregister(), however, does not cover the entire duration when resctrl FS is mounted.

Move signal_handler_register() and signal_handler_unregister() calls from per test files into resctrl_tests.c to properly unmount resctrl fs. In order to not add signal_handler_register()/unregister() n times, create helpers test_prepare() and test_cleanup().

Adjust child process kill() call in ctrlc_handler() to only be invoked if the child was already forked.

Fixes: caddc0fbe495 ("selftests/resctrl: Move resctrl FS mount/umount to higher level") Signed-off-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Cc: stable@vger.kernel.org

---

tools/testing/selftests/resctrl/cat_test.c | 8 --- .../testing/selftests/resctrl/resctrl_tests.c | 65 +++++++++++-------- tools/testing/selftests/resctrl/resctrl_val.c | 22 +++---- 3 files changed, 48 insertions(+), 47 deletions(-)

diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c index 97b87285ab2a..224ba8544d8a 100644 --- a/tools/testing/selftests/resctrl/cat_test.c +++ b/tools/testing/selftests/resctrl/cat_test.c @@ -167,12 +167,6 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type) strcpy(param.filename, RESULT_FILE_NAME1); param.num_of_runs = 0; param.cpu_no = sibling_cpu_no;

• } else {

• ret = signal_handler_register();
  

• if (ret) {
  

• 	kill(bm_pid, SIGKILL);
  

• 	goto out;
  

• }
  

  }

remove(param.filename); @@ -209,10 +203,8 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type) } close(pipefd[0]); kill(bm_pid, SIGKILL);

• signal_handler_unregister();
  

  }

-out: cat_test_cleanup(); return ret; diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c b/tools/testing/selftests/resctrl/resctrl_tests.c index 823672a20a43..524ba83d7568 100644 --- a/tools/testing/selftests/resctrl/resctrl_tests.c +++ b/tools/testing/selftests/resctrl/resctrl_tests.c @@ -67,21 +67,41 @@ void tests_cleanup(void) cat_test_cleanup(); } -static void run_mbm_test(const char * const *benchmark_cmd, int cpu_no) +static int test_prepare() { int res;

• ksft_print_msg("Starting MBM BW change ...\n");

• res = signal_handler_register();
• if (res)

• return res;
  

res = mount_resctrlfs(); if (res) {

• signal_handler_unregister();
  

  ksft_exit_fail_msg("Failed to mount resctrl FS\n");

• return;
  

• return res;
  

  }
• return 0;

+}

+static void test_cleanup() +{

• umount_resctrlfs();
• signal_handler_unregister();

+}

Thank you for adding these.

+static void run_mbm_test(const char * const *benchmark_cmd, int cpu_no) +{

• int res;
• ksft_print_msg("Starting MBM BW change ...\n");
• if (test_prepare())

• return;
  

I am not sure about this. With this exit the kselftest machinery is not aware of the test passing or failing. I wonder if there should not rather be a "goto" here that triggers ksft_test_result()? This needs some more thought though. First, with this change test_prepare() officially gains responsibility to determine if a failure is transient (just a single test fails) or permanent (no use trying any other tests if this fails). For the former it would then be up to the caller to call ksft_test_result() and for the latter test_prepare() will call ksft_exit_fail_msg(). Second, that SNC warning may be an inconvenience with a new goto. Here it may be ok to print that message before the test failure?

if (!validate_resctrl_feature_request(MBM_STR) || (get_vendor() != ARCH_INTEL)) { ksft_test_result_skip("Hardware does not support MBM or MBM is disabled\n");

• goto umount;
  

• goto cleanup;
  

  }

res = mbm_bw_change(cpu_no, benchmark_cmd); @@ -89,8 +109,8 @@ static void run_mbm_test(const char * const *benchmark_cmd, int cpu_no) if ((get_vendor() == ARCH_INTEL) && res) ksft_print_msg("Intel MBM may be inaccurate when Sub-NUMA Clustering is enabled. Check BIOS configuration.\n"); -umount:

• umount_resctrlfs();

+cleanup:

• test_cleanup();

} static void run_mba_test(const char * const *benchmark_cmd, int cpu_no) @@ -99,22 +119,19 @@ static void run_mba_test(const char * const *benchmark_cmd, int cpu_no) ksft_print_msg("Starting MBA Schemata change ...\n");

• res = mount_resctrlfs();
• if (res) {

• ksft_exit_fail_msg("Failed to mount resctrl FS\n");
  

• if (test_prepare()) return;

• }

if (!validate_resctrl_feature_request(MBA_STR) || (get_vendor() != ARCH_INTEL)) { ksft_test_result_skip("Hardware does not support MBA or MBA is disabled\n");

• goto umount;
  

• goto cleanup;
  

  }

res = mba_schemata_change(cpu_no, benchmark_cmd); ksft_test_result(!res, "MBA: schemata change\n"); -umount:

• umount_resctrlfs();

+cleanup:

• test_cleanup();

} static void run_cmt_test(const char * const *benchmark_cmd, int cpu_no) @@ -123,15 +140,12 @@ static void run_cmt_test(const char * const *benchmark_cmd, int cpu_no) ksft_print_msg("Starting CMT test ...\n");

• res = mount_resctrlfs();
• if (res) {

• ksft_exit_fail_msg("Failed to mount resctrl FS\n");
  

• if (test_prepare()) return;

• }

if (!validate_resctrl_feature_request(CMT_STR)) { ksft_test_result_skip("Hardware does not support CMT or CMT is disabled\n");

• goto umount;
  

• goto cleanup;
  

  }

res = cmt_resctrl_val(cpu_no, 5, benchmark_cmd); @@ -139,8 +153,8 @@ static void run_cmt_test(const char * const *benchmark_cmd, int cpu_no) if ((get_vendor() == ARCH_INTEL) && res) ksft_print_msg("Intel CMT may be inaccurate when Sub-NUMA Clustering is enabled. Check BIOS configuration.\n"); -umount:

• umount_resctrlfs();

+cleanup:

• test_cleanup();

} static void run_cat_test(int cpu_no, int no_of_bits) @@ -149,22 +163,19 @@ static void run_cat_test(int cpu_no, int no_of_bits) ksft_print_msg("Starting CAT test ...\n");

• res = mount_resctrlfs();
• if (res) {

• ksft_exit_fail_msg("Failed to mount resctrl FS\n");
  

• if (test_prepare()) return;

• }

if (!validate_resctrl_feature_request(CAT_STR)) { ksft_test_result_skip("Hardware does not support CAT or CAT is disabled\n");

• goto umount;
  

• goto cleanup;
  

  }

res = cat_perf_miss_val(cpu_no, no_of_bits, "L3"); ksft_test_result(!res, "CAT: test\n"); -umount:

• umount_resctrlfs();

+cleanup:

• test_cleanup();

} int main(int argc, char **argv) diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c index 51963a6f2186..a9fe61133119 100644 --- a/tools/testing/selftests/resctrl/resctrl_val.c +++ b/tools/testing/selftests/resctrl/resctrl_val.c @@ -468,7 +468,9 @@ pid_t bm_pid, ppid; void ctrlc_handler(int signum, siginfo_t *info, void *ptr) {

• kill(bm_pid, SIGKILL);

• /* Only kill child after bm_pid is set after fork() */
• if (bm_pid)

• kill(bm_pid, SIGKILL);
  

  umount_resctrlfs(); tests_cleanup(); ksft_print_msg("Ending\n\n");

@@ -485,6 +487,8 @@ int signal_handler_register(void) struct sigaction sigact; int ret = 0;

• bm_pid = 0;

Since this is an initialization fix in this area ... what do you think of also initializing sigact? It could just be a change to struct sigaction sigact = {};

This will prevent registering a signal handler with uninitialized sa_flags.

Reinette