1 /* Copyright (C) 2003-2013 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
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/>. */
21 #include <lowlevellock.h>
24 #include <stap-probe.h>
27 /* Acquire write lock for RWLOCK. */
29 __pthread_rwlock_wrlock (rwlock)
30 pthread_rwlock_t *rwlock;
34 LIBC_PROBE (wrlock_entry, 1, rwlock);
36 /* Make sure we are alone. */
37 lll_lock (rwlock->__data.__lock, rwlock->__data.__shared);
41 /* Get the rwlock if there is no writer and no reader. */
42 if (rwlock->__data.__writer == 0 && rwlock->__data.__nr_readers == 0)
44 /* Mark self as writer. */
45 rwlock->__data.__writer = THREAD_GETMEM (THREAD_SELF, tid);
47 LIBC_PROBE (wrlock_acquire_write, 1, rwlock);
51 /* Make sure we are not holding the rwlock as a writer. This is
52 a deadlock situation we recognize and report. */
53 if (__builtin_expect (rwlock->__data.__writer
54 == THREAD_GETMEM (THREAD_SELF, tid), 0))
60 /* Remember that we are a writer. */
61 if (++rwlock->__data.__nr_writers_queued == 0)
63 /* Overflow on number of queued writers. */
64 --rwlock->__data.__nr_writers_queued;
69 int waitval = rwlock->__data.__writer_wakeup;
72 lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
74 /* Wait for the writer or reader(s) to finish. */
75 lll_futex_wait (&rwlock->__data.__writer_wakeup, waitval,
76 rwlock->__data.__shared);
79 lll_lock (rwlock->__data.__lock, rwlock->__data.__shared);
81 /* To start over again, remove the thread from the writer list. */
82 --rwlock->__data.__nr_writers_queued;
85 /* We are done, free the lock. */
86 lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
91 weak_alias (__pthread_rwlock_wrlock, pthread_rwlock_wrlock)
92 hidden_def (__pthread_rwlock_wrlock)