Re: [PATCH v7 5/6] selftests/resctrl: Commonize the signal handler register/unregister for all tests

[Ilpo Järvinen]

On Mon, 13 Feb 2023, Shaopeng Tan wrote:

> After creating a child process with fork() in CAT test, if 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

therefore

> 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.
> 
> To reuse the signal handler to kill 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>

This looks okay.

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>

As a general comment, it would be probably nicer structure to put all
IPC related code into ipc.c rather than have it in the test related files
(mainly signal handling, pipe write/wait).

> ---
>  tools/testing/selftests/resctrl/cat_test.c    |  9 ++-
>  tools/testing/selftests/resctrl/fill_buf.c    | 14 ----
>  tools/testing/selftests/resctrl/resctrl.h     |  2 +
>  tools/testing/selftests/resctrl/resctrl_val.c | 66 ++++++++++++++-----
>  4 files changed, 58 insertions(+), 33 deletions(-)
> 
> diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
> index 477b62dac546..0bdf0305a506 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;
>  
> @@ -181,6 +180,12 @@ 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);
> @@ -217,8 +222,10 @@ 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();
>  	if (bm_pid)
>  		umount_resctrlfs();
> diff --git a/tools/testing/selftests/resctrl/fill_buf.c b/tools/testing/selftests/resctrl/fill_buf.c
> index 56ccbeae0638..322c6812e15c 100644
> --- a/tools/testing/selftests/resctrl/fill_buf.c
> +++ b/tools/testing/selftests/resctrl/fill_buf.c
> @@ -33,14 +33,6 @@ static void sb(void)
>  #endif
>  }
>  
> -static void ctrl_handler(int signo)
> -{
> -	free(startptr);
> -	printf("\nEnding\n");
> -	sb();
> -	exit(EXIT_SUCCESS);
> -}
> -
>  static void cl_flush(void *p)
>  {
>  #if defined(__i386) || defined(__x86_64)
> @@ -198,12 +190,6 @@ int run_fill_buf(unsigned long span, int malloc_and_init_memory,
>  	unsigned long long cache_size = span;
>  	int ret;
>  
> -	/* set up ctrl-c handler */
> -	if (signal(SIGINT, ctrl_handler) == SIG_ERR)
> -		printf("Failed to catch SIGINT!\n");
> -	if (signal(SIGHUP, ctrl_handler) == SIG_ERR)
> -		printf("Failed to catch SIGHUP!\n");
> -
>  	ret = fill_cache(cache_size, malloc_and_init_memory, memflush, op,
>  			 resctrl_val);
>  	if (ret) {
> diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
> index f0ded31fb3c7..92b59d2f603d 100644
> --- a/tools/testing/selftests/resctrl/resctrl.h
> +++ b/tools/testing/selftests/resctrl/resctrl.h
> @@ -107,6 +107,8 @@ void mba_test_cleanup(void);
>  int get_cbm_mask(char *cache_type, char *cbm_mask);
>  int get_cache_size(int cpu_no, char *cache_type, unsigned long *cache_size);
>  void ctrlc_handler(int signum, siginfo_t *info, void *ptr);
> +int signal_handler_register(void);
> +void signal_handler_unregister(void);
>  int cat_val(struct resctrl_val_param *param);
>  void cat_test_cleanup(void);
>  int cat_perf_miss_val(int cpu_no, int no_of_bits, char *cache_type);
> diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c
> index 6948843bf995..7c8d5c25e6da 100644
> --- a/tools/testing/selftests/resctrl/resctrl_val.c
> +++ b/tools/testing/selftests/resctrl/resctrl_val.c
> @@ -476,6 +476,45 @@ void ctrlc_handler(int signum, siginfo_t *info, void *ptr)
>  	exit(EXIT_SUCCESS);
>  }
>  
> +/*
> + * Register CTRL-C handler for parent, as it has to kill
> + * child process before exiting.
> + */
> +int signal_handler_register(void)
> +{
> +	struct sigaction sigact;
> +	int ret = 0;
> +
> +	sigact.sa_sigaction = ctrlc_handler;
> +	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 = -1;
> +	}
> +	return ret;
> +}
> +
> +/*
> + * Reset signal handler to SIG_DFL.
> + * Non-Value return because the caller should keep
> + * the error code of other path even if sigaction fails.
> + */
> +void signal_handler_unregister(void)
> +{
> +	struct sigaction sigact;
> +
> +	sigact.sa_handler = SIG_DFL;
> +	sigemptyset(&sigact.sa_mask);
> +	if (sigaction(SIGINT, &sigact, NULL) ||
> +	    sigaction(SIGTERM, &sigact, NULL) ||
> +	    sigaction(SIGHUP, &sigact, NULL)) {
> +		perror("# sigaction");
> +	}
> +}
> +
>  /*
>   * print_results_bw:	the memory bandwidth results are stored in a file
>   * @filename:		file that stores the results
> @@ -671,39 +710,28 @@ int resctrl_val(char **benchmark_cmd, struct resctrl_val_param *param)
>  
>  	ksft_print_msg("Benchmark PID: %d\n", bm_pid);
>  
> -	/*
> -	 * Register CTRL-C handler for parent, as it has to kill benchmark
> -	 * before exiting
> -	 */
> -	sigact.sa_sigaction = ctrlc_handler;
> -	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;
> +	ret = signal_handler_register();
> +	if (ret)
>  		goto out;
> -	}
>  
>  	value.sival_ptr = benchmark_cmd;
>  
>  	/* Taskset benchmark to specified cpu */
>  	ret = taskset_benchmark(bm_pid, param->cpu_no);
>  	if (ret)
> -		goto out;
> +		goto unregister;
>  
>  	/* Write benchmark to specified control&monitoring grp in resctrl FS */
>  	ret = write_bm_pid_to_resctrl(bm_pid, param->ctrlgrp, param->mongrp,
>  				      resctrl_val);
>  	if (ret)
> -		goto out;
> +		goto unregister;
>  
>  	if (!strncmp(resctrl_val, MBM_STR, sizeof(MBM_STR)) ||
>  	    !strncmp(resctrl_val, MBA_STR, sizeof(MBA_STR))) {
>  		ret = initialize_mem_bw_imc();
>  		if (ret)
> -			goto out;
> +			goto unregister;
>  
>  		initialize_mem_bw_resctrl(param->ctrlgrp, param->mongrp,
>  					  param->cpu_no, resctrl_val);
> @@ -718,7 +746,7 @@ int resctrl_val(char **benchmark_cmd, struct resctrl_val_param *param)
>  		    sizeof(pipe_message)) {
>  			perror("# failed reading message from child process");
>  			close(pipefd[0]);
> -			goto out;
> +			goto unregister;
>  		}
>  	}
>  	close(pipefd[0]);
> @@ -727,7 +755,7 @@ int resctrl_val(char **benchmark_cmd, struct resctrl_val_param *param)
>  	if (sigqueue(bm_pid, SIGUSR1, value) == -1) {
>  		perror("# sigqueue SIGUSR1 to child");
>  		ret = errno;
> -		goto out;
> +		goto unregister;
>  	}
>  
>  	/* Give benchmark enough time to fully run */
> @@ -761,6 +789,8 @@ int resctrl_val(char **benchmark_cmd, struct resctrl_val_param *param)
>  		}
>  	}
>  
> +unregister:
> +	signal_handler_unregister();
>  out:
>  	kill(bm_pid, SIGKILL);
>  	umount_resctrlfs();
>