1 /* Copyright (C) 2002, 2003, 2004, 2007 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 "pthreadP.h"
21
22
23 int
24 attribute_protected
__pthread_cond_destroy(pthread_cond_t * cond)25 __pthread_cond_destroy (
26 pthread_cond_t *cond)
27 {
28 int pshared = (cond->__data.__mutex == (void *) ~0l)
29 ? LLL_SHARED : LLL_PRIVATE;
30
31 /* Make sure we are alone. */
32 lll_lock (cond->__data.__lock, pshared);
33
34 if (cond->__data.__total_seq > cond->__data.__wakeup_seq)
35 {
36 /* If there are still some waiters which have not been
37 woken up, this is an application bug. */
38 lll_unlock (cond->__data.__lock, pshared);
39 return EBUSY;
40 }
41
42 /* Tell pthread_cond_*wait that this condvar is being destroyed. */
43 cond->__data.__total_seq = -1ULL;
44
45 /* If there are waiters which have been already signalled or
46 broadcasted, but still are using the pthread_cond_t structure,
47 pthread_cond_destroy needs to wait for them. */
48 unsigned int nwaiters = cond->__data.__nwaiters;
49
50 if (nwaiters >= (1 << COND_NWAITERS_SHIFT))
51 {
52 /* Wake everybody on the associated mutex in case there are
53 threads that have been requeued to it.
54 Without this, pthread_cond_destroy could block potentially
55 for a long time or forever, as it would depend on other
56 thread's using the mutex.
57 When all threads waiting on the mutex are woken up, pthread_cond_wait
58 only waits for threads to acquire and release the internal
59 condvar lock. */
60 if (cond->__data.__mutex != NULL
61 && cond->__data.__mutex != (void *) ~0l)
62 {
63 pthread_mutex_t *mut = (pthread_mutex_t *) cond->__data.__mutex;
64 lll_futex_wake (&mut->__data.__lock, INT_MAX,
65 PTHREAD_MUTEX_PSHARED (mut));
66 }
67
68 do
69 {
70 lll_unlock (cond->__data.__lock, pshared);
71
72 lll_futex_wait (&cond->__data.__nwaiters, nwaiters, pshared);
73
74 lll_lock (cond->__data.__lock, pshared);
75
76 nwaiters = cond->__data.__nwaiters;
77 }
78 while (nwaiters >= (1 << COND_NWAITERS_SHIFT));
79 }
80
81 return 0;
82 }
83 weak_alias(__pthread_cond_destroy, pthread_cond_destroy)
84