1  /* Test mutexes.
       2     Copyright (C) 2000-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library;  if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #define _GNU_SOURCE
      20  
      21  #include <pthread.h>
      22  #include <assert.h>
      23  #include <unistd.h>
      24  #include <error.h>
      25  #include <errno.h>
      26  #include <stdio.h>
      27  
      28  #define THREADS 500
      29  
      30  void *
      31  foo (void *arg)
      32  {
      33    pthread_mutex_t *mutex = arg;
      34    pthread_mutex_lock (mutex);
      35    pthread_mutex_unlock (mutex);
      36    return mutex;
      37  }
      38  
      39  int
      40  main (int argc, char **argv)
      41  {
      42    int i;
      43    error_t err;
      44    pthread_t tid[THREADS];
      45    pthread_mutex_t mutex[THREADS];
      46  
      47    for (i = 0; i < THREADS; i++)
      48      {
      49        pthread_mutex_init (&mutex[i], 0);
      50        pthread_mutex_lock (&mutex[i]);
      51        err = pthread_create (&tid[i], 0, foo, &mutex[i]);
      52        if (err)
      53  	error (1, err, "pthread_create");
      54        sched_yield ();
      55      }
      56  
      57    for (i = THREADS - 1; i >= 0; i--)
      58      {
      59        void *ret;
      60        pthread_mutex_unlock (&mutex[i]);
      61        err = pthread_join (tid[i], &ret);
      62        if (err)
      63  	error (1, err, "pthread_join");
      64        assert (ret == &mutex[i]);
      65      }
      66  
      67    return 0;
      68  }