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/* Test that pthread_cancel succeeds during thread exit.
Copyright (C) 2021 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/>. */
/* This test tries to trigger an internal race condition in
pthread_cancel, where the cancellation signal is sent after the
thread has begun the cancellation process. This can result in a
spurious ESRCH error. For the original bug 12889, the window is
quite small, so the bug was not reproduced in every run. */
#include <stdbool.h>
#include <stddef.h>
#include <support/check.h>
#include <support/xthread.h>
#include <support/xunistd.h>
#include <sys/select.h>
#include <unistd.h>
/* Set to true by timeout_thread_function when the test should
terminate. */
static bool timeout;
static void *
timeout_thread_function (void *unused)
{
usleep (5 * 1000 * 1000);
__atomic_store_n (&timeout, true, __ATOMIC_RELAXED);
return NULL;
}
/* Used for blocking the select function below. */
static int pipe_fds[2];
static void *
canceled_thread_function (void *unused)
{
while (true)
{
fd_set rfs;
fd_set wfs;
fd_set efs;
FD_ZERO (&rfs);
FD_ZERO (&wfs);
FD_ZERO (&efs);
FD_SET (pipe_fds[0], &rfs);
/* If the cancellation request is recognized early, the thread
begins exiting while the cancellation signal arrives. */
select (FD_SETSIZE, &rfs, &wfs, &efs, NULL);
}
return NULL;
}
static int
do_test (void)
{
xpipe (pipe_fds);
pthread_t thr_timeout = xpthread_create (NULL, timeout_thread_function, NULL);
while (!__atomic_load_n (&timeout, __ATOMIC_RELAXED))
{
pthread_t thr = xpthread_create (NULL, canceled_thread_function, NULL);
xpthread_cancel (thr);
TEST_VERIFY (xpthread_join (thr) == PTHREAD_CANCELED);
}
xpthread_join (thr_timeout);
xclose (pipe_fds[0]);
xclose (pipe_fds[1]);
return 0;
}
#include <support/test-driver.c>
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