projects / thirdparty / glibc.git / blame
| Commit | Line | Data |
|---|---|---|
| 33574c17 | 1 | /* Acquire a rwlock for writing. Generic version. |
| 04277e02 | 2 | Copyright (C) 2002-2019 Free Software Foundation, Inc. |
| 33574c17 ST |
3 | This file is part of the GNU C Library. |
| 4 | ||
| 5 | The GNU C Library is free software; you can redistribute it and/or | |
| ad2b41bf ST |
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. | |
| 33574c17 ST |
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 | |
| ad2b41bf | 13 | Lesser General Public License for more details. |
| 33574c17 | 14 | |
| ad2b41bf ST |
15 | You should have received a copy of the GNU Lesser General Public |
| 16 | License along with the GNU C Library; if not, see | |
| 5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
| 33574c17 ST |
18 | |
| 19 | #include <pthread.h> | |
| 20 | #include <assert.h> | |
| 21 | ||
| 22 | #include <pt-internal.h> | |
| 23 | ||
| 24 | /* Acquire RWLOCK for writing blocking until *ABSTIME if we cannot get | |
| 25 | it. As a special GNU extension, if ABSTIME is NULL then the wait | |
| 26 | shall not time out. */ | |
| 27 | int | |
| 28 | __pthread_rwlock_timedwrlock_internal (struct __pthread_rwlock *rwlock, | |
| 29 | const struct timespec *abstime) | |
| 30 | { | |
| 31 | error_t err; | |
| 32 | int drain; | |
| 33 | struct __pthread *self; | |
| 34 | ||
| 35 | __pthread_spin_lock (&rwlock->__lock); | |
| 36 | if (__pthread_spin_trylock (&rwlock->__held) == 0) | |
| 37 | /* Successfully acquired the lock. */ | |
| 38 | { | |
| 39 | assert (rwlock->__readerqueue == 0); | |
| 40 | assert (rwlock->__writerqueue == 0); | |
| 41 | assert (rwlock->__readers == 0); | |
| 42 | ||
| 43 | __pthread_spin_unlock (&rwlock->__lock); | |
| 44 | return 0; | |
| 45 | } | |
| 46 | ||
| 47 | /* The lock is busy. */ | |
| 48 | ||
| 49 | if (abstime != NULL && (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)) | |
| 50 | return EINVAL; | |
| 51 | ||
| 52 | self = _pthread_self (); | |
| 53 | ||
| 54 | /* Add ourselves to the queue. */ | |
| 55 | __pthread_enqueue (&rwlock->__writerqueue, self); | |
| 56 | __pthread_spin_unlock (&rwlock->__lock); | |
| 57 | ||
| 58 | /* Block the thread. */ | |
| 59 | if (abstime != NULL) | |
| 60 | err = __pthread_timedblock (self, abstime, CLOCK_REALTIME); | |
| 61 | else | |
| 62 | { | |
| 63 | err = 0; | |
| 64 | __pthread_block (self); | |
| 65 | } | |
| 66 | ||
| 67 | __pthread_spin_lock (&rwlock->__lock); | |
| 68 | if (self->prevp == NULL) | |
| 69 | /* Another thread removed us from the queue, which means a wakeup message | |
| 70 | has been sent. It was either consumed while we were blocking, or | |
| 71 | queued after we timed out and before we acquired the rwlock lock, in | |
| 72 | which case the message queue must be drained. */ | |
| 73 | drain = err ? 1 : 0; | |
| 74 | else | |
| 75 | { | |
| 76 | /* We're still in the queue. Noone attempted to wake us up, i.e. we | |
| 77 | timed out. */ | |
| 78 | __pthread_dequeue (self); | |
| 79 | drain = 0; | |
| 80 | } | |
| 81 | __pthread_spin_unlock (&rwlock->__lock); | |
| 82 | ||
| 83 | if (drain) | |
| 84 | __pthread_block (self); | |
| 85 | ||
| 86 | if (err) | |
| 87 | { | |
| 88 | assert (err == ETIMEDOUT); | |
| 89 | return err; | |
| 90 | } | |
| 91 | ||
| 92 | assert (rwlock->__readers == 0); | |
| 93 | ||
| 94 | return 0; | |
| 95 | } | |
| 96 | ||
| 97 | int | |
| 98 | __pthread_rwlock_timedwrlock (struct __pthread_rwlock *rwlock, | |
| 99 | const struct timespec *abstime) | |
| 100 | { | |
| 101 | return __pthread_rwlock_timedwrlock_internal (rwlock, abstime); | |
| 102 | } | |
| 103 | weak_alias (__pthread_rwlock_timedwrlock, pthread_rwlock_timedwrlock) |