1 | /* Copyright (C) 2002-2016 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | Contributed by Ulrich Drepper <drepper@redhat.com>, 2002. |
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 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <errno.h> |
20 | #include <stdlib.h> |
21 | |
22 | #include <atomic.h> |
23 | #include "pthreadP.h" |
24 | |
25 | |
26 | int |
27 | pthread_tryjoin_np (pthread_t threadid, void **thread_return) |
28 | { |
29 | struct pthread *self; |
30 | struct pthread *pd = (struct pthread *) threadid; |
31 | |
32 | /* Make sure the descriptor is valid. */ |
33 | if (DEBUGGING_P && __find_in_stack_list (pd) == NULL) |
34 | /* Not a valid thread handle. */ |
35 | return ESRCH; |
36 | |
37 | /* Is the thread joinable?. */ |
38 | if (IS_DETACHED (pd)) |
39 | /* We cannot wait for the thread. */ |
40 | return EINVAL; |
41 | |
42 | self = THREAD_SELF; |
43 | if (pd == self || self->joinid == pd) |
44 | /* This is a deadlock situation. The threads are waiting for each |
45 | other to finish. Note that this is a "may" error. To be 100% |
46 | sure we catch this error we would have to lock the data |
47 | structures but it is not necessary. In the unlikely case that |
48 | two threads are really caught in this situation they will |
49 | deadlock. It is the programmer's problem to figure this |
50 | out. */ |
51 | return EDEADLK; |
52 | |
53 | /* Return right away if the thread hasn't terminated yet. */ |
54 | if (pd->tid != 0) |
55 | return EBUSY; |
56 | |
57 | /* Wait for the thread to finish. If it is already locked something |
58 | is wrong. There can only be one waiter. */ |
59 | if (atomic_compare_and_exchange_bool_acq (&pd->joinid, self, NULL)) |
60 | /* There is already somebody waiting for the thread. */ |
61 | return EINVAL; |
62 | |
63 | /* Store the return value if the caller is interested. */ |
64 | if (thread_return != NULL) |
65 | *thread_return = pd->result; |
66 | |
67 | |
68 | /* Free the TCB. */ |
69 | __free_tcb (pd); |
70 | |
71 | return 0; |
72 | } |
73 | |