linux-kernel - Re: [PATCH v3 1/5] selftests/resctrl: Kill child process before parent process terminates if SIGTERM is received

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Date:   Fri, 18 Feb 2022 13:10:10 -0700
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Shaopeng Tan <tan.shaopeng@...fujitsu.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Shuah Khan <shuah@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH v3 1/5] selftests/resctrl: Kill child process before
 parent process terminates if SIGTERM is received

On 2/15/22 7:26 PM, Shaopeng Tan wrote:
> In kselftest framework, a sub test is run using the timeout utility
> and it will send SIGTERM to the test upon timeout.
> 
> In resctrl_tests, a child process is created by fork() to
> run benchmark but SIGTERM is not set in sigaction().
> If SIGTERM signal is received, the parent process will be killed,
> but the child process still exists.
> 
> kill child process before parent process terminates
> if SIGTERM signal is received.
> 
> Signed-off-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> ---
> Some important feedbacks from v1&v2 are addressed as follows:
> 
> - Change the order so that current patch 3/3 becomes 1/3. Since without
>    the SIGTERM fix, the test would hang if run from the kselftest framework.
>    => I changed the order and the SIGTERM fix now becomes patch [1/5].
> 
> - Describe that the test is run using the timeout utility and
>    it will send SIGTERM to the test upon timeout.
>    => I updated the changelog to include this information.
> 
> - Describe changes in imperative mood, and address this in all patches.
>    See Documentation/process/submitting-patches.rst for more details.
>    => I described all my patches' changelog in imperative mood and
>       deleted "This commit".
> 
> - +	    sigaction(SIGTERM, &sigact, NULL) ||
>    This snippet is preceded with a comment that describes its usage
>    you could also update it with the expanded use of the kselftest framework.
>    => I don't think it is necessary to add other comments.
>       Since the current comment already states "Register CTRL-C handler for parent,
>       as it has to kill benchmark before exiting", So, when SIGTERM comes,
>       the benchmark(child process) should be killed before parent process terminates,
>       but it was missing.
> 
>   tools/testing/selftests/resctrl/resctrl_val.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c
> index 95224345c78e..b32b96356ec7 100644
> --- a/tools/testing/selftests/resctrl/resctrl_val.c
> +++ b/tools/testing/selftests/resctrl/resctrl_val.c
> @@ -678,6 +678,7 @@ int resctrl_val(char **benchmark_cmd, struct resctrl_val_param *param)
>   	sigemptyset(&sigact.sa_mask);
>   	sigact.sa_flags = SA_SIGINFO;
>   	if (sigaction(SIGINT, &sigact, NULL) ||
> +	    sigaction(SIGTERM, &sigact, NULL) ||
>   	    sigaction(SIGHUP, &sigact, NULL)) {
>   		perror("# sigaction");
>   		ret = errno;
> 

This looks good to me.

Reviewed-by: Shuah Khan <skhan@...uxfoundation.org>

thanks,
-- Shuah