1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *  * Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *  * Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *    the documentation and/or other materials provided with the
13 *    distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <errno.h>
30
31#include "private/bionic_futex.h"
32#include "pthread_internal.h"
33
34int pthread_join(pthread_t t, void** return_value) {
35  if (t == pthread_self()) {
36    return EDEADLK;
37  }
38
39  pthread_internal_t* thread = __pthread_internal_find(t);
40  if (thread == NULL) {
41    return ESRCH;
42  }
43
44  ThreadJoinState old_state = THREAD_NOT_JOINED;
45  while ((old_state == THREAD_NOT_JOINED || old_state == THREAD_EXITED_NOT_JOINED) &&
46         !atomic_compare_exchange_weak(&thread->join_state, &old_state, THREAD_JOINED)) {
47  }
48
49  if (old_state == THREAD_DETACHED || old_state == THREAD_JOINED) {
50    return EINVAL;
51  }
52
53  pid_t tid = thread->tid;
54  volatile int* tid_ptr = &thread->tid;
55
56  // We set thread->join_state to THREAD_JOINED with atomic operation,
57  // so no one is going to remove this thread except us.
58
59  // Wait for the thread to actually exit, if it hasn't already.
60  while (*tid_ptr != 0) {
61    __futex_wait(tid_ptr, tid, NULL);
62  }
63
64  if (return_value) {
65    *return_value = thread->return_value;
66  }
67
68  __pthread_internal_remove_and_free(thread);
69  return 0;
70}
71