88 lines
2.6 KiB
C
88 lines
2.6 KiB
C
/* Test rwlock with PREFER_WRITER_NONRECURSIVE_NP (bug 23861).
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Copyright (C) 2018-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <pthread.h>
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#include <support/xthread.h>
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/* We choose 10 iterations because this happens to be able to trigger the
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stall on contemporary hardware. */
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#define LOOPS 10
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/* We need 3 threads to trigger bug 23861. One thread as a writer, and
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two reader threads. The test verifies that the second-to-last reader
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is able to notify the *last* reader that it should be done waiting.
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If the second-to-last reader fails to notify the last reader or does
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so incorrectly then the last reader may stall indefinitely. */
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#define NTHREADS 3
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_Atomic int do_exit;
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pthread_rwlockattr_t mylock_attr;
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pthread_rwlock_t mylock;
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void *
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run_loop (void *a)
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{
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while (!do_exit)
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{
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if (random () & 1)
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{
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xpthread_rwlock_wrlock (&mylock);
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xpthread_rwlock_unlock (&mylock);
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}
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else
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{
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xpthread_rwlock_rdlock (&mylock);
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xpthread_rwlock_unlock (&mylock);
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}
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}
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return NULL;
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}
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int
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do_test (void)
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{
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xpthread_rwlockattr_init (&mylock_attr);
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xpthread_rwlockattr_setkind_np (&mylock_attr,
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PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
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xpthread_rwlock_init (&mylock, &mylock_attr);
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for (int n = 0; n < LOOPS; n++)
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{
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pthread_t tids[NTHREADS];
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do_exit = 0;
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for (int i = 0; i < NTHREADS; i++)
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tids[i] = xpthread_create (NULL, run_loop, NULL);
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/* Let the threads run for some time. */
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sleep (1);
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printf ("Exiting...");
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fflush (stdout);
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do_exit = 1;
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for (int i = 0; i < NTHREADS; i++)
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xpthread_join (tids[i]);
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printf ("done.\n");
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}
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pthread_rwlock_destroy (&mylock);
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pthread_rwlockattr_destroy (&mylock_attr);
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return 0;
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}
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#define TIMEOUT (DEFAULT_TIMEOUT + 3 * LOOPS)
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#include <support/test-driver.c>
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