Re: [PATCH v5 4/5] selftests/resctrl: Cleanup properly when an error occurs in CAT test

Hi Shaopeng,

On 1/10/2023 11:58 PM, Shaopeng Tan wrote:

After creating a child process with fork() in CAT test, if there is an

Please delete the "there is" so that it reads "if an error occurs"

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@jp.fujitsu.com

tools/testing/selftests/resctrl/cat_test.c | 26 +++++---- tools/testing/selftests/resctrl/fill_buf.c | 14 ----- tools/testing/selftests/resctrl/resctrl.h | 2 + tools/testing/selftests/resctrl/resctrl_val.c | 56 ++++++++++++++----- 4 files changed, 59 insertions(+), 39 deletions(-)

diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c index 6a8306b0a109..87302b882929 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 +180,29 @@ 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)
  

• 	goto out;
  

The "goto" will unregister the signal handler. Is that necessary if the registration failed?

Also, if signal_handler_register() fails then the child will keep running and run its test ... would child not then run forever?

} 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);
  

if (bm_pid == 0) { /* Tell parent that child is ready */ close(pipefd[0]); pipe_message = 1; if (write(pipefd[1], &pipe_message, sizeof(pipe_message)) <

•     sizeof(pipe_message)) {
  

• 	close(pipefd[1]);
  

•     sizeof(pipe_message))
  

• 	/*
  

• 	 * Just print the error message.
  

• 	 * Let while(1) run and wait for itself to be killed.
  

• 	 */
  perror("# failed signaling parent process");
  

• 	return errno;
  

• }
  

close(pipefd[1]); while (1) @@ -226,5 +226,7 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type) if (bm_pid) umount_resctrlfs();

• return 0;

+out:

• ret = signal_handler_unregister();
• return ret;

Be careful here ... any earlier value of "ret" will be overwritten with the result of signal_handler_unregister(). I think the return of signal_handler_unregister() can be ignored. There will be an error message if it failed.

} 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..14a5e21497e1 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); +int 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..91a3cf8b308b 100644 --- a/tools/testing/selftests/resctrl/resctrl_val.c +++ b/tools/testing/selftests/resctrl/resctrl_val.c @@ -476,6 +476,46 @@ void ctrlc_handler(int signum, siginfo_t *info, void *ptr) exit(EXIT_SUCCESS); } +struct sigaction sigact;

+/*

• • Register CTRL-C handler for parent, as it has to kill
• • child process before exiting
• */

+int signal_handler_register(void) +{

• int ret = 0;
• struct sigaction sigact;

Why is there a global sigact as well as a local sigact?

Also, please do keep using reverse fir-tree format.

• 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;
  

I understand that you copied from the original code here but I do think there is an issue here in that errno is undefined after a library call. perror() will print errno message so keeping it (errno) around may not be useful. Please do keep the custom of returning negative value as error though. I think just returning -1 would work.

• }
• return ret;

+}

+/* reset signal handler to SIG_DFL. */ +int signal_handler_unregister(void) +{

• int ret = 0;
• 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");
  

• ret = errno;
  

Same comment about errno and returning -1 on failure.

• }
• return ret;

+}

/*

• print_results_bw: the memory bandwidth results are stored in a file
• @filename: file that stores the results

@@ -671,20 +711,9 @@ 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; @@ -764,6 +793,7 @@ int resctrl_val(char **benchmark_cmd, struct resctrl_val_param *param) out: kill(bm_pid, SIGKILL); umount_resctrlfs();

• ret = signal_handler_unregister();

return ret;

Same here ... any earlier value of ret will be overwritten with result of signal_handler_unregister().

Reinette

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