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128 lines
2.9 KiB
C
128 lines
2.9 KiB
C
/* Test rdlock overflow.
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Copyright (C) 2000-2020 Free Software Foundation, Inc.
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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 License as
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published by the Free Software Foundation; either version 2.1 of the
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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; see the file COPYING.LIB. If
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not, see <https://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <error.h>
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <time.h>
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#include <unistd.h>
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#include <pthreadP.h>
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#define NREADERS 15
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#define READTRIES 5000
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#define DELAY 1000000
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static pthread_rwlock_t lock = PTHREAD_RWLOCK_INITIALIZER;
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static int eagain_returned = 0;
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static int success_returned = 0;
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static void *
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reader_thread (void *nr)
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{
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struct timespec delay;
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int n;
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delay.tv_sec = 0;
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delay.tv_nsec = DELAY;
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for (n = 0; n < READTRIES; ++n)
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{
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int err = pthread_rwlock_rdlock (&lock);
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if (err == EAGAIN)
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{
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atomic_store_relaxed (&eagain_returned, 1);
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continue;
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}
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else if (err == 0)
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atomic_store_relaxed (&success_returned, 1);
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else
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{
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puts ("rdlock failed");
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exit (1);
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}
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nanosleep (&delay, NULL);
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if (pthread_rwlock_unlock (&lock) != 0)
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{
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puts ("unlock for reader failed");
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exit (1);
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}
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}
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return NULL;
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}
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static int
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do_test (void)
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{
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pthread_t thrd[NREADERS];
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int n;
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void *res;
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/* Set the rwlock so that it's close to a reader overflow.
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PTHREAD_RWLOCK_WRPHASE and PTHREAD_RWLOCK_WRLOCK are zero initially. */
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unsigned int readers = PTHREAD_RWLOCK_READER_OVERFLOW
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- ((NREADERS / 3) << PTHREAD_RWLOCK_READER_SHIFT);
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lock.__data.__readers = readers;
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for (n = 0; n < NREADERS; ++n)
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if (pthread_create (&thrd[n], NULL, reader_thread,
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(void *) (long int) n) != 0)
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{
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puts ("reader create failed");
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exit (1);
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}
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/* Wait for all the threads. */
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for (n = 0; n < NREADERS; ++n)
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if (pthread_join (thrd[n], &res) != 0)
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{
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puts ("reader join failed");
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exit (1);
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}
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if (atomic_load_relaxed (&eagain_returned) == 0)
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{
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puts ("EAGAIN has never been returned");
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exit (1);
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}
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if (atomic_load_relaxed (&success_returned) == 0)
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{
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puts ("rdlock was never successfully acquired");
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exit (1);
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}
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if (lock.__data.__readers != readers)
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{
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puts ("__readers in rwlock differs from initial value");
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exit (1);
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}
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return 0;
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}
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#define TIMEOUT 100
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#define TEST_FUNCTION do_test ()
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#include "../test-skeleton.c"
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