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/* Testing race while enabling lock elision.
Copyright (C) 2018-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <pthread.h>
#include <unistd.h>
#include <getopt.h>
#include <support/support.h>
#include <support/xthread.h>
static pthread_barrier_t barrier;
static pthread_mutex_t mutex;
static long long int iteration_count = 1000000;
static unsigned int thread_count = 3;
static void *
thr_func (void *arg)
{
long long int i;
for (i = 0; i < iteration_count; i++)
{
if ((uintptr_t) arg == 0)
{
xpthread_mutex_destroy (&mutex);
xpthread_mutex_init (&mutex, NULL);
}
xpthread_barrier_wait (&barrier);
/* Test if enabling lock elision works if it is enabled concurrently.
There was a race in FORCE_ELISION macro which leads to either
pthread_mutex_destroy returning EBUSY as the owner was recorded
by pthread_mutex_lock - in "normal mutex" code path - but was not
resetted in pthread_mutex_unlock - in "elision" code path.
Or it leads to the assertion in nptl/pthread_mutex_lock.c:
assert (mutex->__data.__owner == 0);
Please ensure that the test is run with lock elision:
export GLIBC_TUNABLES=glibc.elision.enable=1 */
xpthread_mutex_lock (&mutex);
xpthread_mutex_unlock (&mutex);
xpthread_barrier_wait (&barrier);
}
return NULL;
}
static int
do_test (void)
{
unsigned int i;
printf ("Starting %d threads to run %lld iterations.\n",
thread_count, iteration_count);
pthread_t *threads = xmalloc (thread_count * sizeof (pthread_t));
xpthread_barrier_init (&barrier, NULL, thread_count);
xpthread_mutex_init (&mutex, NULL);
for (i = 0; i < thread_count; i++)
threads[i] = xpthread_create (NULL, thr_func, (void *) (uintptr_t) i);
for (i = 0; i < thread_count; i++)
xpthread_join (threads[i]);
xpthread_barrier_destroy (&barrier);
free (threads);
return EXIT_SUCCESS;
}
#define OPT_ITERATIONS 10000
#define OPT_THREADS 10001
#define CMDLINE_OPTIONS \
{ "iterations", required_argument, NULL, OPT_ITERATIONS }, \
{ "threads", required_argument, NULL, OPT_THREADS },
static void
cmdline_process (int c)
{
long long int arg = strtoll (optarg, NULL, 0);
switch (c)
{
case OPT_ITERATIONS:
if (arg > 0)
iteration_count = arg;
break;
case OPT_THREADS:
if (arg > 0 && arg < 100)
thread_count = arg;
break;
}
}
#define CMDLINE_PROCESS cmdline_process
#define TIMEOUT 50
#include <support/test-driver.c>
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