Re: [PATCH 1/5] selftests/resctrl: Extend signal handler coverage to unmount on receiving signal

[Reinette Chatre]

Hi Ilpo,

On 9/13/2023 3:01 AM, Ilpo Järvinen wrote:
> On Tue, 12 Sep 2023, Reinette Chatre wrote:
>> On 9/11/2023 4:19 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() call
>>> into the test functions in resctrl_tests.c to properly unmount resctrl
>>> fs. Adjust child process kill() call in ctrlc_handler() to only be
>>> invoked if the child was already forked.
>>
>> Thank you for catching this.
>>
>>>
>>> Fixes: caddc0fbe495 ("selftests/resctrl: Move resctrl FS mount/umount to higher level")
>>> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
>>> Cc: <stable@xxxxxxxxxxxxxxx>
>>> ---
>>>  tools/testing/selftests/resctrl/cat_test.c    |  8 -------
>>>  .../testing/selftests/resctrl/resctrl_tests.c | 24 +++++++++++++++++++
>>>  tools/testing/selftests/resctrl/resctrl_val.c | 22 ++++++++---------
>>>  3 files changed, 34 insertions(+), 20 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..3d66fbdc2df3 100644
>>> --- a/tools/testing/selftests/resctrl/resctrl_tests.c
>>> +++ b/tools/testing/selftests/resctrl/resctrl_tests.c
>>> @@ -73,8 +73,13 @@ static void run_mbm_test(const char * const *benchmark_cmd, int cpu_no)
>>>  
>>>  	ksft_print_msg("Starting MBM BW change ...\n");
>>>  
>>> +	res = signal_handler_register();
>>> +	if (res)
>>> +		return;
>>> +
>>>  	res = mount_resctrlfs();
>>>  	if (res) {
>>> +		signal_handler_unregister();
>>>  		ksft_exit_fail_msg("Failed to mount resctrl FS\n");
>>>  		return;
>>>  	}
>>> @@ -91,6 +96,7 @@ static void run_mbm_test(const char * const *benchmark_cmd, int cpu_no)
>>>  
>>>  umount:
>>>  	umount_resctrlfs();
>>> +	signal_handler_unregister();
>>>  }
>>>  
>>>  static void run_mba_test(const char * const *benchmark_cmd, int cpu_no)
>>> @@ -99,8 +105,13 @@ static void run_mba_test(const char * const *benchmark_cmd, int cpu_no)
>>>  
>>>  	ksft_print_msg("Starting MBA Schemata change ...\n");
>>>  
>>> +	res = signal_handler_register();
>>> +	if (res)
>>> +		return;
>>> +
>>>  	res = mount_resctrlfs();
>>>  	if (res) {
>>> +		signal_handler_unregister();
>>>  		ksft_exit_fail_msg("Failed to mount resctrl FS\n");
>>>  		return;
>>>  	}
>>> @@ -115,6 +126,7 @@ static void run_mba_test(const char * const *benchmark_cmd, int cpu_no)
>>>  
>>>  umount:
>>>  	umount_resctrlfs();
>>> +	signal_handler_unregister();
>>>  }
>>>  
>>
>> This adds more duplicated code for every test. Have you considered a
>> single test setup function that can be used to mount resctrl FS and setup
>> the signal handler paired with a single test teardown function?
> 
> Yes. Consolidating all these is among my not-yet submitted patches.
> I just had to do a backport-friendly Fixes patch first for this.
> 

Could you please help me understand how the duplicate calls are more
backport friendly?

Reinette