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Message-ID: <20240406151057.GB3060@redhat.com>
Date: Sat, 6 Apr 2024 17:10:58 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: John Stultz <jstultz@...gle.com>, Marco Elver <elver@...gle.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
Dmitry Vyukov <dvyukov@...gle.com>, kasan-dev@...glegroups.com,
Edward Liaw <edliaw@...gle.com>,
Carlos Llamas <cmllamas@...gle.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] selftests/timers/posix_timers: reimplement
check_timer_distribution()
Dmitry, Thomas,
To simplify the review I've attached the code with this patch applied below.
Yes, this changes the "semantics" of check_timer_distribution(), perhaps it
should be renamed.
But I do not see a better approach, and in fact I think that
Test that all running threads _eventually_ receive CLOCK_PROCESS_CPUTIME_ID
is the wrong goal.
Do you agree?
Oleg.
-------------------------------------------------------------------------------
static pthread_t ctd_thread;
static volatile int ctd_count, ctd_failed;
static void ctd_sighandler(int sig)
{
if (pthread_self() != ctd_thread)
ctd_failed = 1;
ctd_count--;
}
static void *ctd_thread_func(void *arg)
{
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;
/* 1/10 seconds to ensure the leader sleeps */
usleep(10000);
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";
while (ctd_count > 0 && !ctd_failed)
;
if (timer_delete(id))
return "Can't delete timer";
return NULL;
}
/*
* Test that only the running thread receives the timer signal.
*/
static int check_timer_distribution(void)
{
const char *errmsg;
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;
if (ctd_failed)
ksft_test_result_skip("No signal distribution. Assuming old kernel\n");
else
ksft_test_result_pass("check signal distribution\n");
return 0;
err:
ksft_print_msg(errmsg);
return -1;
}
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