add changelog for previous commit
[glibc.git] / nptl / pthread_rwlock_trywrlock.c
blob918a8f28da2a4bd45438445a5dc28b4e5906bd7c
1 /* Copyright (C) 2002-2015 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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.
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.
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/>. */
19 #include <errno.h>
20 #include "pthreadP.h"
21 #include <lowlevellock.h>
22 #include <elide.h>
25 int
26 __pthread_rwlock_trywrlock (pthread_rwlock_t *rwlock)
28 int result = EBUSY;
30 if (ELIDE_TRYLOCK (rwlock->__data.__rwelision,
31 rwlock->__data.__lock == 0
32 && rwlock->__data.__nr_readers == 0
33 && rwlock->__data.__writer, 1))
34 return 0;
36 lll_lock (rwlock->__data.__lock, rwlock->__data.__shared);
38 if (rwlock->__data.__writer == 0 && rwlock->__data.__nr_readers == 0)
40 rwlock->__data.__writer = THREAD_GETMEM (THREAD_SELF, tid);
41 result = 0;
44 lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
46 return result;
48 strong_alias (__pthread_rwlock_trywrlock, pthread_rwlock_trywrlock)