Re: [PATCH v6 4/5] selftests/resctrl: Cleanup properly when an error occurs in CAT test

[Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>]

On Tue, 31 Jan 2023, Shaopeng Tan wrote:

> After creating a child process with fork() in CAT test, if an error
> occurs or a signal such as SIGINT is received, the parent process will
> be terminated immediately, and therefor the child process will not
> be killed and also resctrlfs is not unmounted.
> 
> There is a signal handler registered in CMT/MBM/MBA tests, which kills
> child process, unmount resctrlfs, cleanups result files, etc., if a
> signal such as SIGINT is received.
>
> Commonize the signal handler registered for CMT/MBM/MBA tests and reuse
> it in CAT too.
> 
> To reuse the signal handler, make the child process in CAT wait to be
> killed by parent process in any case (an error occurred or a signal was
> received), and when killing child process use global bm_pid instead of
> local bm_pid.
> 
> Also, since the MBA/MBA/CMT/CAT are run in order, unregister the signal
> handler at the end of each test so that the signal handler cannot be
> inherited by other tests.
> 
> Signed-off-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
> ---
>  tools/testing/selftests/resctrl/cat_test.c    | 28 ++++----
>  tools/testing/selftests/resctrl/fill_buf.c    | 14 ----
>  tools/testing/selftests/resctrl/resctrl.h     |  2 +
>  tools/testing/selftests/resctrl/resctrl_val.c | 70 +++++++++++++------
>  4 files changed, 68 insertions(+), 46 deletions(-)
> 
> diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
> index 6a8306b0a109..3524fa88e3a4 100644
> --- a/tools/testing/selftests/resctrl/cat_test.c
> +++ b/tools/testing/selftests/resctrl/cat_test.c
> @@ -103,7 +103,6 @@ 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;
>  
>  	cache_size = 0;
>  
> @@ -181,28 +180,31 @@ 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);
>  

>  	ret = cat_val(&param);
> -	if (ret)
> -		return ret;
> -
> -	ret = check_results(&param);
> -	if (ret)
> -		return ret;
> +	if (ret == 0)
> +		ret = check_results(&param);

It would be take this program flow fix out of the signal handler change
into a separate change.

-- 
 i.