1/* This testcase is part of GDB, the GNU debugger.
2
3   Copyright 2018-2020 Free Software Foundation, Inc.
4
5   This program is free software; you can redistribute it and/or modify
6   it under the terms of the GNU General Public License as published by
7   the Free Software Foundation; either version 3 of the License, or
8   (at your option) any later version.
9
10   This program 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
13   GNU General Public License for more details.
14
15   You should have received a copy of the GNU General Public License
16   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
17
18#include <pthread.h>
19#include <stdio.h>
20#include <stdlib.h>
21#include <assert.h>
22#define NUM_THREADS 4
23
24/* Crude spin lock.  Threads all spin until this is set to 0.  */
25int go = 1;
26
27/* Thread function, just spin until GO is set to 0.  */
28void *
29perform_work (void *argument)
30{
31  /* Cast to volatile to ensure that ARGUMENT is loaded each time around
32     the loop.  */
33  while (*((volatile int*) argument))
34    {
35      /* Nothing.  */
36    }
37  return NULL;
38}
39
40/* The spin loop for the main thread.  */
41void
42function (void)
43{
44  (void) perform_work (&go);
45  printf ("Finished from function\n");
46}
47
48/* Main program, create some threads which all spin waiting for GO to be
49   set to 0.  */
50int
51main (void)
52{
53  pthread_t threads[NUM_THREADS];
54  int result_code;
55  unsigned index;
56
57  /* Create some threads.  */
58  for (index = 0; index < NUM_THREADS; ++index)
59    {
60      printf ("In main: creating thread %d\n", index);
61      result_code = pthread_create (&threads[index], NULL, perform_work, &go);
62      assert (!result_code);
63    }
64
65  function ();
66
67  /* Wait for each thread to complete.  */
68  for (index = 0; index < NUM_THREADS; ++index)
69    {
70      /* Block until thread INDEX completes.  */
71      result_code = pthread_join (threads[index], NULL);
72      assert (!result_code);
73      printf ("In main: thread %d has completed\n", index);
74    }
75  printf ("In main: All threads completed successfully\n");
76  return 0;
77}
78