linux-kernel - Re: [PATCH v3 4/5] selftests/resctrl: Cleanup properly when an error occurs in CAT test

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Date:   Wed, 2 Nov 2022 03:41:47 -0600
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 4/5] selftests/resctrl: Cleanup properly when an error
 occurs in CAT test

On 11/1/22 03:43, Shaopeng Tan wrote:
> After creating a child process with fork() in CAT test, if there is
> an error occurs or such as a SIGINT signal is received, the parent
> process will be terminated immediately, but the child process will not
> be killed and also umount_resctrlfs() will not be called.
> 
> Add a signal handler like other tests to kill child process, umount
> resctrlfs, cleanup result files, etc. when an error occurs.
> 
> Signed-off-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> ---
>   tools/testing/selftests/resctrl/cat_test.c | 28 +++++++++++++++-------
>   1 file changed, 19 insertions(+), 9 deletions(-)
> 
> diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
> index 6a8306b0a109..5f81817f4366 100644
> --- a/tools/testing/selftests/resctrl/cat_test.c
> +++ b/tools/testing/selftests/resctrl/cat_test.c
> @@ -98,12 +98,21 @@ void cat_test_cleanup(void)
>   	remove(RESULT_FILE_NAME2);
>   }
>   
> +static void ctrl_handler(int signo)
> +{
> +	kill(bm_pid, SIGKILL);
> +	umount_resctrlfs();
> +	tests_cleanup();
> +	ksft_print_msg("Ending\n\n");

Is there a reason to print this message? Remove it unless it serves
a purpose.

> +
> +	exit(EXIT_SUCCESS);
> +}
> +
>   int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
>   {
>   	unsigned long l_mask, l_mask_1;
>   	int ret, pipefd[2], sibling_cpu_no;
>   	char pipe_message;
> -	pid_t bm_pid;

Odd. bm_pid is used below - why remove it here?

>   
>   	cache_size = 0;
>   
> @@ -181,17 +190,19 @@ 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 {
> +		/* set up ctrl-c handler */
> +		if (signal(SIGINT, ctrl_handler) == SIG_ERR ||
> +		    signal(SIGHUP, ctrl_handler) == SIG_ERR ||
> +		    signal(SIGTERM, ctrl_handler) == SIG_ERR)
> +			printf("Failed to catch SIGNAL!\n");

Is perror() more appropriate here?

>   	}
>   
>   	remove(param.filename);
>   
>   	ret = cat_val(&param);
> -	if (ret)
> -		return ret;
> -
> -	ret = check_results(&param);
> -	if (ret)
> -		return ret;
> +	if (ret == 0)
> +		ret = check_results(&param);

Why not use a goto in error case to do umount_resctrlfs() instead of changing
the conditionals?

>   
>   	if (bm_pid == 0) {
>   		/* Tell parent that child is ready */
> @@ -201,7 +212,6 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
>   		    sizeof(pipe_message)) {
>   			close(pipefd[1]);
>   			perror("# failed signaling parent process");
> -			return errno;
>   		}
>   
>   		close(pipefd[1]);
> @@ -226,5 +236,5 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
>   	if (bm_pid)
>   		umount_resctrlfs();
>   
> -	return 0;
> +	return ret;
>   }


With these changes made:

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

thanks,
-- Shuah