1PTHREAD_RWLOCK_UNLOCK(3P) POSIX Programmer's Manual PTHREAD_RWLOCK_UNLOCK(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 pthread_rwlock_unlock — unlock a read-write lock object
13
15 #include <pthread.h>
16 int pthread_rwlock_unlock(pthread_rwlock_t *rwlock);
18
20 The pthread_rwlock_unlock() function shall release a lock held on the
21 read-write lock object referenced by rwlock. Results are undefined if
22 the read-write lock rwlock is not held by the calling thread.
23 If this function is called to release a read lock from the read-write
25 lock object and there are other read locks currently held on this read-
26 write lock object, the read-write lock object remains in the read
27 locked state. If this function releases the last read lock for this
28 read-write lock object, the read-write lock object shall be put in the
29 unlocked state with no owners.
30 If this function is called to release a write lock for this read-write
32 lock object, the read-write lock object shall be put in the unlocked
33 state.
34 If there are threads blocked on the lock when it becomes available, the
36 scheduling policy shall determine which thread(s) shall acquire the
37 lock. If the Thread Execution Scheduling option is supported, when
38 threads executing with the scheduling policies SCHED_FIFO, SCHED_RR, or
39 SCHED_SPORADIC are waiting on the lock, they shall acquire the lock in
40 priority order when the lock becomes available. For equal priority
41 threads, write locks shall take precedence over read locks. If the
42 Thread Execution Scheduling option is not supported, it is implementa‐
43 tion-defined whether write locks take precedence over read locks.
44 Results are undefined if this function is called with an uninitialized
46 read-write lock.
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49 If successful, the pthread_rwlock_unlock() function shall return zero;
50 otherwise, an error number shall be returned to indicate the error.
51
53 The pthread_rwlock_unlock() function shall not return an error code of
54 [EINTR].
55 The following sections are informative.
57
59 None.
60
62 None.
63
65 If an implementation detects that the value specified by the rwlock
66 argument to pthread_rwlock_unlock() does not refer to an initialized
67 read-write lock object, it is recommended that the function should fail
68 and report an [EINVAL] error.
69 If an implementation detects that the value specified by the rwlock
71 argument to pthread_rwlock_unlock() refers to a read-write lock object
72 for which the current thread does not hold a lock, it is recommended
73 that the function should fail and report an [EPERM] error.
74
76 None.
77
79 pthread_rwlock_destroy(), pthread_rwlock_rdlock(), pthread_rwlock_time‐
80 drdlock(), pthread_rwlock_timedwrlock(), pthread_rwlock_trywrlock()
81 The Base Definitions volume of POSIX.1‐2017, Section 4.12, Memory Syn‐
83 chronization, <pthread.h>
84
86 Portions of this text are reprinted and reproduced in electronic form
87 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
88 table Operating System Interface (POSIX), The Open Group Base Specifi‐
89 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
90 Electrical and Electronics Engineers, Inc and The Open Group. In the
91 event of any discrepancy between this version and the original IEEE and
92 The Open Group Standard, the original IEEE and The Open Group Standard
93 is the referee document. The original Standard can be obtained online
94 at http://www.opengroup.org/unix/online.html .
95 Any typographical or formatting errors that appear in this page are
97 most likely to have been introduced during the conversion of the source
98 files to man page format. To report such errors, see https://www.ker‐
99 nel.org/doc/man-pages/reporting_bugs.html .
100IEEE/The Open Group 2017 PTHREAD_RWLOCK_UNLOCK(3P)