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 <shlib-compat.h>
21#include "pthreadP.h"
22#include <stap-probe.h>
23
24
25int
26__pthread_cond_destroy (pthread_cond_t *cond)
27{
28 int pshared = (cond->__data.__mutex == (void *) ~0l)
29 ? LLL_SHARED : LLL_PRIVATE;
30
31 LIBC_PROBE (cond_destroy, 1, cond);
32
33 /* Make sure we are alone. */
34 lll_lock (cond->__data.__lock, pshared);
35
36 if (cond->__data.__total_seq > cond->__data.__wakeup_seq)
37 {
38 /* If there are still some waiters which have not been
39 woken up, this is an application bug. */
40 lll_unlock (cond->__data.__lock, pshared);
41 return EBUSY;
42 }
43
44 /* Tell pthread_cond_*wait that this condvar is being destroyed. */
45 cond->__data.__total_seq = -1ULL;
46
47 /* If there are waiters which have been already signalled or
48 broadcasted, but still are using the pthread_cond_t structure,
49 pthread_cond_destroy needs to wait for them. */
50 unsigned int nwaiters = cond->__data.__nwaiters;
51
52 if (nwaiters >= (1 << COND_NWAITERS_SHIFT))
53 {
54 /* Wake everybody on the associated mutex in case there are
55 threads that have been requeued to it.
56 Without this, pthread_cond_destroy could block potentially
57 for a long time or forever, as it would depend on other
58 thread's using the mutex.
59 When all threads waiting on the mutex are woken up, pthread_cond_wait
60 only waits for threads to acquire and release the internal
61 condvar lock. */
62 if (cond->__data.__mutex != NULL
63 && cond->__data.__mutex != (void *) ~0l)
64 {
65 pthread_mutex_t *mut = (pthread_mutex_t *) cond->__data.__mutex;
66 lll_futex_wake (&mut->__data.__lock, INT_MAX,
67 PTHREAD_MUTEX_PSHARED (mut));
68 }
69
70 do
71 {
72 lll_unlock (cond->__data.__lock, pshared);
73
74 lll_futex_wait (&cond->__data.__nwaiters, nwaiters, pshared);
75
76 lll_lock (cond->__data.__lock, pshared);
77
78 nwaiters = cond->__data.__nwaiters;
79 }
80 while (nwaiters >= (1 << COND_NWAITERS_SHIFT));
81 }
82
83 return 0;
84}
85versioned_symbol (libpthread, __pthread_cond_destroy,
86 pthread_cond_destroy, GLIBC_2_3_2);
87