]>
Commit | Line | Data |
---|---|---|
5acf7263 | 1 | /* Copyright (C) 2003-2012 Free Software Foundation, Inc. |
a88c9263 UD |
2 | This file is part of the GNU C Library. |
3 | Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003. | |
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 | |
59ba27a6 PE |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ | |
a88c9263 UD |
18 | |
19 | #include <errno.h> | |
20 | #include <sysdep.h> | |
21 | #include <lowlevellock.h> | |
22 | #include <pthread.h> | |
23 | #include <pthreadP.h> | |
5acf7263 | 24 | #include <stap-probe.h> |
a88c9263 UD |
25 | |
26 | ||
27 | /* Acquire write lock for RWLOCK. */ | |
28 | int | |
29 | __pthread_rwlock_wrlock (rwlock) | |
30 | pthread_rwlock_t *rwlock; | |
31 | { | |
32 | int result = 0; | |
33 | ||
5acf7263 RM |
34 | LIBC_PROBE (wrlock_entry, 1, rwlock); |
35 | ||
c5be0f71 | 36 | /* Make sure we are alone. */ |
e51deae7 | 37 | lll_lock (rwlock->__data.__lock, rwlock->__data.__shared); |
a88c9263 UD |
38 | |
39 | while (1) | |
40 | { | |
41 | /* Get the rwlock if there is no writer and no reader. */ | |
b80770b2 | 42 | if (rwlock->__data.__writer == 0 && rwlock->__data.__nr_readers == 0) |
a88c9263 UD |
43 | { |
44 | /* Mark self as writer. */ | |
4ad0bbf4 | 45 | rwlock->__data.__writer = THREAD_GETMEM (THREAD_SELF, tid); |
5acf7263 RM |
46 | |
47 | LIBC_PROBE (wrlock_acquire_write, 1, rwlock); | |
a88c9263 UD |
48 | break; |
49 | } | |
50 | ||
51 | /* Make sure we are not holding the rwlock as a writer. This is | |
52 | a deadlock situation we recognize and report. */ | |
4ad0bbf4 UD |
53 | if (__builtin_expect (rwlock->__data.__writer |
54 | == THREAD_GETMEM (THREAD_SELF, tid), 0)) | |
a88c9263 UD |
55 | { |
56 | result = EDEADLK; | |
57 | break; | |
58 | } | |
59 | ||
60 | /* Remember that we are a writer. */ | |
61 | if (++rwlock->__data.__nr_writers_queued == 0) | |
62 | { | |
63 | /* Overflow on number of queued writers. */ | |
64 | --rwlock->__data.__nr_writers_queued; | |
65 | result = EAGAIN; | |
66 | break; | |
67 | } | |
68 | ||
18a53579 UD |
69 | int waitval = rwlock->__data.__writer_wakeup; |
70 | ||
a88c9263 | 71 | /* Free the lock. */ |
e51deae7 | 72 | lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared); |
a88c9263 UD |
73 | |
74 | /* Wait for the writer or reader(s) to finish. */ | |
eb7721f2 | 75 | lll_futex_wait (&rwlock->__data.__writer_wakeup, waitval, |
e51deae7 | 76 | rwlock->__data.__shared); |
a88c9263 UD |
77 | |
78 | /* Get the lock. */ | |
e51deae7 | 79 | lll_lock (rwlock->__data.__lock, rwlock->__data.__shared); |
a88c9263 UD |
80 | |
81 | /* To start over again, remove the thread from the writer list. */ | |
82 | --rwlock->__data.__nr_writers_queued; | |
a88c9263 UD |
83 | } |
84 | ||
85 | /* We are done, free the lock. */ | |
e51deae7 | 86 | lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared); |
a88c9263 UD |
87 | |
88 | return result; | |
89 | } | |
90 | ||
91 | weak_alias (__pthread_rwlock_wrlock, pthread_rwlock_wrlock) | |
4d17e683 | 92 | hidden_def (__pthread_rwlock_wrlock) |