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bfff8b1b | 1 | /* Copyright (C) 2002-2017 Free Software Foundation, Inc. |
76a50749 UD |
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 | |
59ba27a6 PE |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ | |
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18 | |
19 | #include <errno.h> | |
20 | #include <stdlib.h> | |
21 | ||
8dea90aa | 22 | #include <atomic.h> |
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23 | #include "pthreadP.h" |
24 | ||
5acf7263 RM |
25 | #include <stap-probe.h> |
26 | ||
76a50749 UD |
27 | |
28 | static void | |
29 | cleanup (void *arg) | |
30 | { | |
22bb134c UD |
31 | /* If we already changed the waiter ID, reset it. The call cannot |
32 | fail for any reason but the thread not having done that yet so | |
33 | there is no reason for a loop. */ | |
4f7c7e83 UD |
34 | (void) atomic_compare_and_exchange_bool_acq ((struct pthread **) arg, NULL, |
35 | THREAD_SELF); | |
76a50749 UD |
36 | } |
37 | ||
38 | ||
39 | int | |
14bb4e57 | 40 | pthread_join (pthread_t threadid, void **thread_return) |
76a50749 | 41 | { |
76a50749 UD |
42 | struct pthread *pd = (struct pthread *) threadid; |
43 | ||
44 | /* Make sure the descriptor is valid. */ | |
8c2e9a29 | 45 | if (INVALID_NOT_TERMINATED_TD_P (pd)) |
76a50749 UD |
46 | /* Not a valid thread handle. */ |
47 | return ESRCH; | |
48 | ||
49 | /* Is the thread joinable?. */ | |
50 | if (IS_DETACHED (pd)) | |
51 | /* We cannot wait for the thread. */ | |
52 | return EINVAL; | |
53 | ||
22bb134c UD |
54 | struct pthread *self = THREAD_SELF; |
55 | int result = 0; | |
56 | ||
5acf7263 RM |
57 | LIBC_PROBE (pthread_join, 1, threadid); |
58 | ||
22bb134c UD |
59 | /* During the wait we change to asynchronous cancellation. If we |
60 | are canceled the thread we are waiting for must be marked as | |
61 | un-wait-ed for again. */ | |
62 | pthread_cleanup_push (cleanup, &pd->joinid); | |
63 | ||
64 | /* Switch to asynchronous cancellation. */ | |
65 | int oldtype = CANCEL_ASYNC (); | |
66 | ||
67 | if ((pd == self | |
68 | || (self->joinid == pd | |
69 | && (pd->cancelhandling | |
70 | & (CANCELING_BITMASK | CANCELED_BITMASK | EXITING_BITMASK | |
71 | | TERMINATED_BITMASK)) == 0)) | |
72 | && !CANCEL_ENABLED_AND_CANCELED (self->cancelhandling)) | |
76a50749 UD |
73 | /* This is a deadlock situation. The threads are waiting for each |
74 | other to finish. Note that this is a "may" error. To be 100% | |
75 | sure we catch this error we would have to lock the data | |
76 | structures but it is not necessary. In the unlikely case that | |
77 | two threads are really caught in this situation they will | |
78 | deadlock. It is the programmer's problem to figure this | |
79 | out. */ | |
22bb134c | 80 | result = EDEADLK; |
76a50749 UD |
81 | /* Wait for the thread to finish. If it is already locked something |
82 | is wrong. There can only be one waiter. */ | |
22bb134c UD |
83 | else if (__builtin_expect (atomic_compare_and_exchange_bool_acq (&pd->joinid, |
84 | self, | |
85 | NULL), 0)) | |
76a50749 | 86 | /* There is already somebody waiting for the thread. */ |
22bb134c UD |
87 | result = EINVAL; |
88 | else | |
89 | /* Wait for the child. */ | |
90 | lll_wait_tid (pd->tid); | |
76a50749 UD |
91 | |
92 | ||
93 | /* Restore cancellation mode. */ | |
94 | CANCEL_RESET (oldtype); | |
95 | ||
96 | /* Remove the handler. */ | |
97 | pthread_cleanup_pop (0); | |
98 | ||
99 | ||
a1ffb40e | 100 | if (__glibc_likely (result == 0)) |
22bb134c UD |
101 | { |
102 | /* We mark the thread as terminated and as joined. */ | |
103 | pd->tid = -1; | |
7ac5b8e2 | 104 | |
22bb134c UD |
105 | /* Store the return value if the caller is interested. */ |
106 | if (thread_return != NULL) | |
107 | *thread_return = pd->result; | |
76a50749 UD |
108 | |
109 | ||
22bb134c UD |
110 | /* Free the TCB. */ |
111 | __free_tcb (pd); | |
112 | } | |
76a50749 | 113 | |
5acf7263 RM |
114 | LIBC_PROBE (pthread_join_ret, 3, threadid, result, pd->result); |
115 | ||
22bb134c | 116 | return result; |
76a50749 | 117 | } |