/* Test rdlock overflow.

   Copyright (C) 2000-2018 Free Software Foundation, Inc.

   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; see the file COPYING.LIB.  If

   not, see <http://www.gnu.org/licenses/>.  */

#include <errno.h>

#include <error.h>

#include <pthread.h>

#include <stdio.h>

#include <stdlib.h>

#include <time.h>

#include <unistd.h>

#include <pthreadP.h>

#define NREADERS 15

#define READTRIES 5000

#define DELAY   1000000

static pthread_rwlock_t lock = PTHREAD_RWLOCK_INITIALIZER;

static int eagain_returned = 0;

static int success_returned = 0;

static void *

reader_thread (void *nr)

{

  struct timespec delay;

  int n;

  delay.tv_sec = 0;

  delay.tv_nsec = DELAY;

  for (n = 0; n < READTRIES; ++n)

    {

      int err = pthread_rwlock_rdlock (&lock);

      if (err == EAGAIN)

	{

	  atomic_store_relaxed (&eagain_returned, 1);

	  continue;

	}

      else if (err == 0)

	atomic_store_relaxed (&success_returned, 1);

      else

	{

	  puts ("rdlock failed");

	  exit (1);

	}

      nanosleep (&delay, NULL);

      if (pthread_rwlock_unlock (&lock) != 0)

	{

	  puts ("unlock for reader failed");

	  exit (1);

	}

    }

  return NULL;

}

static int

do_test (void)

{

  pthread_t thrd[NREADERS];

  int n;

  void *res;

  /* Set the rwlock so that it's close to a reader overflow.

     PTHREAD_RWLOCK_WRPHASE and PTHREAD_RWLOCK_WRLOCK are zero initially.  */

  unsigned int readers = PTHREAD_RWLOCK_READER_OVERFLOW

      - ((NREADERS / 3) << PTHREAD_RWLOCK_READER_SHIFT);

  lock.__data.__readers = readers;

  for (n = 0; n < NREADERS; ++n)

    if (pthread_create (&thrd[n], NULL, reader_thread,

			(void *) (long int) n) != 0)

      {

	puts ("reader create failed");

	exit (1);

      }

  /* Wait for all the threads.  */

  for (n = 0; n < NREADERS; ++n)

    if (pthread_join (thrd[n], &res) != 0)

      {

	puts ("reader join failed");

	exit (1);

      }

  if (atomic_load_relaxed (&eagain_returned) == 0)

    {

      puts ("EAGAIN has never been returned");

      exit (1);

    }

  if (atomic_load_relaxed (&success_returned) == 0)

    {

      puts ("rdlock was never successfully acquired");

      exit (1);

    }

  if (lock.__data.__readers != readers)

    {

      puts ("__readers in rwlock differs from initial value");

      exit (1);

    }

  return 0;

}

#define TIMEOUT 100

#define TEST_FUNCTION do_test ()

#include "../test-skeleton.c"