Re: [PATCH v4 4/5] selftests/resctrl: Cleanup properly when an error occurs in CAT test

From: Reinette Chatre
Date: Thu Dec 01 2022 - 13:14:06 EST


Hi Shaopeng,

On 12/1/2022 12:20 AM, Shaopeng Tan (Fujitsu) wrote:
> Hi Reinette,
>
>> On 11/30/2022 12:32 AM, Shaopeng Tan (Fujitsu) wrote:
>>
>>> Removing ctrl_handler() is only part of the fix in the next version(v5).
>>> All fixes as follows.
>>>
>>> --- a/tools/testing/selftests/resctrl/cat_test.c
>>> +++ b/tools/testing/selftests/resctrl/cat_test.c
>>> @@ -98,12 +98,17 @@ void cat_test_cleanup(void)
>>> remove(RESULT_FILE_NAME2);
>>> }
>>>
>>> +static void ctrlc_handler_child(int signum, siginfo_t *info, void
>>> +*ptr) {
>>> + exit(EXIT_SUCCESS);
>>> +}
>>> +
>>
>> Could you please elaborate why this is necessary?
>
> If enter "ctrl-c" when running "resctrl_tests -t cat",
> SIGINT will be sent to all processes (parent&child).
>
> At this time, the child process receives a SIGINT signal, but does not take any action.
> In this case the parent process may not call ctrlc_handler() as expected.

Apologies, but I am not able to follow. My understanding is that the
ideal in working an failing case is for the parent to kill the child.
Could you please elaborate why the ctrlc_handler() may not be called?

> Therefore, ctrlc_handler_child() is necessary.
>
> It may be better to ignore the signal, then code can be simple as follows.
> ----
> if (bm_pid == 0) {
> param.mask = l_mask_1;
> strcpy(param.ctrlgrp, "c1");
> strcpy(param.mongrp, "m1");
> param.span = cache_size * n / count_of_bits;
> strcpy(param.filename, RESULT_FILE_NAME1);
> param.num_of_runs = 0;
> param.cpu_no = sibling_cpu_no;
> /* Ignore the signal,and wait to be cleaned up by the parent process */
> sigfillset(&sigact.sa_mask);
> sigact.sa_handler = SIG_IGN;
> //sigact.sa_sigaction = ctrlc_handler_child; //delete
> if (sigaction(SIGINT, &sigact, NULL) ||
> sigaction(SIGTERM, &sigact, NULL) ||
> sigaction(SIGHUP, &sigact, NULL))
> perror("# sigaction");
> } else {

Reinette