[PATCH v2 1/6] selftests/resctrl: Extend signal handler coverage to unmount on receiving signal

Ilpo Järvinen
2023-09-15T15:45:45Z

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() calls
from per test files into resctrl_tests.c to properly unmount resctrl
fs. In order to not add signal_handler_register()/unregister() n times,
create helpers test_prepare() and test_cleanup().

Adjust child process kill() call in ctrlc_handler() to only be invoked
if the child was already forked.

Fixes: caddc0fbe495 ("selftests/resctrl: Move resctrl FS mount/umount to higher level")
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: <stable@vger.kernel.org>
---
tools/testing/selftests/resctrl/cat_test.c | 8 ---
.../testing/selftests/resctrl/resctrl_tests.c | 65 +++++++++++--------
tools/testing/selftests/resctrl/resctrl_val.c | 22 +++----
3 files changed, 48 insertions(+), 47 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..524ba83d7568 100644
--- a/tools/testing/selftests/resctrl/resctrl_tests.c
+++ b/tools/testing/selftests/resctrl/resctrl_tests.c
@@ -67,21 +67,41 @@ void tests_cleanup(void)
cat_test_cleanup();
}

-static void run_mbm_test(const char * const *benchmark_cmd, int cpu_no)
+static int test_prepare()
{
int res;

- ksft_print_msg("Starting MBM BW change ...\n");
+ res = signal_handler_register();
+ if (res)
+ return res;

res = mount_resctrlfs();
if (res) {
+ signal_handler_unregister();
ksft_exit_fail_msg("Failed to mount resctrl FS\n");
- return;
+ return res;
}
+ return 0;
+}
+
+static void test_cleanup()
+{
+ umount_resctrlfs();
+ signal_handler_unregister();
+}
+
+static void run_mbm_test(const char * const *benchmark_cmd, int cpu_no)
+{
+ int res;
+
+ ksft_print_msg("Starting MBM BW change ...\n");
+
+ if (test_prepare())
+ return;

if (!validate_resctrl_feature_request(MBM_STR) || (get_vendor() != ARCH_INTEL)) {
ksft_test_result_skip("Hardware does not support MBM or MBM is disabled\n");
- goto umount;
+ goto cleanup;
}

res = mbm_bw_change(cpu_no, benchmark_cmd);
@@ -89,8 +109,8 @@ static void run_mbm_test(const char * const *benchmark_cmd, int cpu_no)
if ((get_vendor() == ARCH_INTEL) && res)
ksft_print_msg("Intel MBM may be inaccurate when Sub-NUMA Clustering is enabled. Check BIOS configuration.\n");

-umount:
- umount_resctrlfs();
+cleanup:
+ test_cleanup();
}

static void run_mba_test(const char * const *benchmark_cmd, int cpu_no)
@@ -99,22 +119,19 @@ static void run_mba_test(const char * const *benchmark_cmd, int cpu_no)

ksft_print_msg("Starting MBA Schemata change ...\n");

- res = mount_resctrlfs();
- if (res) {
- ksft_exit_fail_msg("Failed to mount resctrl FS\n");
+ if (test_prepare())
return;
- }

if (!validate_resctrl_feature_request(MBA_STR) || (get_vendor() != ARCH_INTEL)) {
ksft_test_result_skip("Hardware does not support MBA or MBA is disabled\n");
- goto umount;
+ goto cleanup;
}

res = mba_schemata_change(cpu_no, benchmark_cmd);
ksft_test_result(!res, "MBA: schemata change\n");

-umount:
- umount_resctrlfs();
+cleanup:
+ test_cleanup();
}

static void run_cmt_test(const char * const *benchmark_cmd, int cpu_no)
@@ -123,15 +140,12 @@ static void run_cmt_test(const char * const *benchmark_cmd, int cpu_no)

ksft_print_msg("Starting CMT test ...\n");

- res = mount_resctrlfs();
- if (res) {
- ksft_exit_fail_msg("Failed to mount resctrl FS\n");
+ if (test_prepare())
return;
- }

if (!validate_resctrl_feature_request(CMT_STR)) {
ksft_test_result_skip("Hardware does not support CMT or CMT is disabled\n");
- goto umount;
+ goto cleanup;
}

res = cmt_resctrl_val(cpu_no, 5, benchmark_cmd);
@@ -139,8 +153,8 @@ static void run_cmt_test(const char * const *benchmark_cmd, int cpu_no)
if ((get_vendor() == ARCH_INTEL) && res)
ksft_print_msg("Intel CMT may be inaccurate when Sub-NUMA Clustering is enabled. Check BIOS configuration.\n");

-umount:
- umount_resctrlfs();
+cleanup:
+ test_cleanup();
}

static void run_cat_test(int cpu_no, int no_of_bits)
@@ -149,22 +163,19 @@ static void run_cat_test(int cpu_no, int no_of_bits)

ksft_print_msg("Starting CAT test ...\n");

- res = mount_resctrlfs();
- if (res) {
- ksft_exit_fail_msg("Failed to mount resctrl FS\n");
+ if (test_prepare())
return;
- }

if (!validate_resctrl_feature_request(CAT_STR)) {
ksft_test_result_skip("Hardware does not support CAT or CAT is disabled\n");
- goto umount;
+ goto cleanup;
}

res = cat_perf_miss_val(cpu_no, no_of_bits, "L3");
ksft_test_result(!res, "CAT: test\n");

-umount:
- umount_resctrlfs();
+cleanup:
+ test_cleanup();
}

int main(int argc, char **argv)
diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c
index 51963a6f2186..a9fe61133119 100644
--- a/tools/testing/selftests/resctrl/resctrl_val.c
+++ b/tools/testing/selftests/resctrl/resctrl_val.c
@@ -468,7 +468,9 @@ pid_t bm_pid, ppid;

void ctrlc_handler(int signum, siginfo_t *info, void *ptr)
{
- kill(bm_pid, SIGKILL);
+ /* Only kill child after bm_pid is set after fork() */
+ if (bm_pid)
+ kill(bm_pid, SIGKILL);
umount_resctrlfs();
tests_cleanup();
ksft_print_msg("Ending\n\n");
@@ -485,6 +487,8 @@ int signal_handler_register(void)
struct sigaction sigact;
int ret = 0;

+ bm_pid = 0;
+
sigact.sa_sigaction = ctrlc_handler;
sigemptyset(&sigact.sa_mask);
sigact.sa_flags = SA_SIGINFO;
@@ -706,10 +710,6 @@ int resctrl_val(const char * const *benchmark_cmd, struct resctrl_val_param *par

ksft_print_msg("Benchmark PID: %d\n", bm_pid);

- ret = signal_handler_register();
- if (ret)
- goto out;
-
/*
* The cast removes constness but nothing mutates benchmark_cmd within
* the context of this process. At the receiving process, it becomes
@@ -721,19 +721,19 @@ int resctrl_val(const char * const *benchmark_cmd, struct resctrl_val_param *par
/* Taskset benchmark to specified cpu */
ret = taskset_benchmark(bm_pid, param->cpu_no);
if (ret)
- goto unregister;
+ goto out;

/* 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 unregister;
+ goto out;

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 unregister;
+ goto out;

initialize_mem_bw_resctrl(param->ctrlgrp, param->mongrp,
param->cpu_no, resctrl_val);
@@ -748,7 +748,7 @@ int resctrl_val(const char * const *benchmark_cmd, struct resctrl_val_param *par
sizeof(pipe_message)) {
perror("# failed reading message from child process");
close(pipefd[0]);
- goto unregister;
+ goto out;
}
}
close(pipefd[0]);
@@ -757,7 +757,7 @@ int resctrl_val(const char * const *benchmark_cmd, struct resctrl_val_param *par
if (sigqueue(bm_pid, SIGUSR1, value) == -1) {
perror("# sigqueue SIGUSR1 to child");
ret = errno;
- goto unregister;
+ goto out;
}

/* Give benchmark enough time to fully run */
@@ -786,8 +786,6 @@ int resctrl_val(const char * const *benchmark_cmd, struct resctrl_val_param *par
}
}

-unregister:
- signal_handler_unregister();
out:
kill(bm_pid, SIGKILL);

--
2.30.2