1 /* Copyright (C) 2002, 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 #include <lowlevellock.h>
22
23
24 int
__pthread_rwlock_tryrdlock(pthread_rwlock_t * rwlock)25 __pthread_rwlock_tryrdlock (
26 pthread_rwlock_t *rwlock)
27 {
28 int result = EBUSY;
29
30 lll_lock (rwlock->__data.__lock, rwlock->__data.__shared);
31
32 if (rwlock->__data.__writer == 0
33 && (rwlock->__data.__nr_writers_queued == 0
34 || PTHREAD_RWLOCK_PREFER_READER_P (rwlock)))
35 {
36 if (__builtin_expect (++rwlock->__data.__nr_readers == 0, 0))
37 {
38 --rwlock->__data.__nr_readers;
39 result = EAGAIN;
40 }
41 else
42 result = 0;
43 }
44
45 lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
46
47 return result;
48 }
49 strong_alias (__pthread_rwlock_tryrdlock, pthread_rwlock_tryrdlock)
50