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

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Date:   Tue, 12 Sep 2023 15:06:17 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
        Shuah Khan <shuah@...nel.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        <linux-kselftest@...r.kernel.org>,
        Maciej Wieczór-Retman 
        <maciej.wieczor-retman@...el.com>
CC:     <linux-kernel@...r.kernel.org>,
        Shaopeng Tan <tan.shaopeng@...fujitsu.com>,
        <stable@...r.kernel.org>
Subject: Re: [PATCH 1/5] selftests/resctrl: Extend signal handler coverage to
 unmount on receiving signal

Hi Ilpo,

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@...ux.intel.com>
> Cc: <stable@...r.kernel.org>
> ---
>  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?

Reinette