On Mon, Apr 08 2024 at 20:49, Oleg Nesterov wrote:
> To me this test should simply do
>
> ksft_test_result(!ctd_failed, "check signal distribution\n");
> return 0;
Right.
> but I am not familiar with tools/testing/selftests/ and I am not sure
> I understand the last email from Thomas.
The discussion started about running new tests on older kernels. As this
is a feature and not a bug fix that obviously fails on older kernels.
So something like the uncompiled below should work.
Thanks,
tglx
---
--- a/tools/testing/selftests/timers/posix_timers.c
+++ b/tools/testing/selftests/timers/posix_timers.c
@@ -184,80 +184,83 @@ static int check_timer_create(int which)
return 0;
}
-int remain;
-__thread int got_signal;
+static pthread_t ctd_thread;
+static volatile int ctd_count, ctd_failed;
-static void *distribution_thread(void *arg)
+static void ctd_sighandler(int sig)
{
- while (__atomic_load_n(&remain, __ATOMIC_RELAXED));
- return NULL;
-}
-
-static void distribution_handler(int nr)
-{
- if (!__atomic_exchange_n(&got_signal, 1, __ATOMIC_RELAXED))
- __atomic_fetch_sub(&remain, 1, __ATOMIC_RELAXED);
+ if (pthread_self() != ctd_thread)
+ ctd_failed = 1;
+ ctd_count--;
}
-/*
- * Test that all running threads _eventually_ receive CLOCK_PROCESS_CPUTIME_ID
- * timer signals. This primarily tests that the kernel does not favour any one.
- */
-static int check_timer_distribution(void)
+static void *ctd_thread_func(void *arg)
{
- int err, i;
- timer_t id;
- const int nthreads = 10;
- pthread_t threads[nthreads];
struct itimerspec val = {
.it_value.tv_sec = 0,
.it_value.tv_nsec = 1000 * 1000,
.it_interval.tv_sec = 0,
.it_interval.tv_nsec = 1000 * 1000,
};
+ timer_t id;
- remain = nthreads + 1; /* worker threads + this thread */
- signal(SIGALRM, distribution_handler);
- err = timer_create(CLOCK_PROCESS_CPUTIME_ID, NULL, &id);
- if (err < 0) {
- ksft_perror("Can't create timer");
- return -1;
- }
- err = timer_settime(id, 0, &val, NULL);
- if (err < 0) {
- ksft_perror("Can't set timer");
- return -1;
- }
+ /* 1/10 seconds to ensure the leader sleeps */
+ usleep(10000);
- for (i = 0; i < nthreads; i++) {
- err = pthread_create(&threads[i], NULL, distribution_thread,
- NULL);
- if (err) {
- ksft_print_msg("Can't create thread: %s (%d)\n",
- strerror(errno), errno);
- return -1;
- }
- }
+ ctd_count = 100;
+ if (timer_create(CLOCK_PROCESS_CPUTIME_ID, NULL, &id))
+ return "Can't create timer";
+ if (timer_settime(id, 0, &val, NULL))
+ return "Can't set timer";
- /* Wait for all threads to receive the signal. */
- while (__atomic_load_n(&remain, __ATOMIC_RELAXED));
+ while (ctd_count > 0 && !ctd_failed)
+ ;
- for (i = 0; i < nthreads; i++) {
- err = pthread_join(threads[i], NULL);
- if (err) {
- ksft_print_msg("Can't join thread: %s (%d)\n",
- strerror(errno), errno);
- return -1;
- }
- }
+ if (timer_delete(id))
+ return "Can't delete timer";
- if (timer_delete(id)) {
- ksft_perror("Can't delete timer");
+ return NULL;
+}
+
+static bool check_kernel_version(unsigned int min_major, unsigned int
min_minor)
+{
+ unsigned int major, minor;
+ struct utsname info;
+
+ uname(&info);
+ if (sscanf(info.release, "%u.%u.", &major, &minor) != 2)
+ ksft_exit_fail();
+ return major > min_major || (major == min_major && minor >= min_minor);
+}
+
+/*
+ * Test that only the running thread receives the timer signal.
+ */
+static int check_timer_distribution(void)
+{
+ const char *errmsg;
+
+ if (!check_kernel_version(6, 3)) {
+ ksft_test_result_skip("check signal distribution (old
kernel)\n");
return 0;
}
- ksft_test_result_pass("check_timer_distribution\n");
+ signal(SIGALRM, ctd_sighandler);
+
+ errmsg = "Can't create thread";
+ if (pthread_create(&ctd_thread, NULL, ctd_thread_func, NULL))
+ goto err;
+
+ errmsg = "Can't join thread";
+ if (pthread_join(ctd_thread, (void **)&errmsg) || errmsg)
+ goto err;
+
+ ksft_test_result(!ctd_failed, "check signal distribution\n");
return 0;
+
+err:
+ ksft_print_msg(errmsg);
+ return -1;
}
int main(int argc, char **argv)
