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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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PTHREAD...K_UNLOCK(3P) POSIX Programmer's Manual PTHREAD...K_UNLOCK(3P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
pthread_rwlock_unlock — unlock a read-write lock object
#include <pthread.h>
int pthread_rwlock_unlock(pthread_rwlock_t *rwlock);
The pthread_rwlock_unlock() function shall release a lock held on
the read-write lock object referenced by rwlock. Results are
undefined if the read-write lock rwlock is not held by the calling
thread.
If this function is called to release a read lock from the read-
write lock object and there are other read locks currently held on
this read-write lock object, the read-write lock object remains in
the read locked state. If this function releases the last read
lock for this read-write lock object, the read-write lock object
shall be put in the unlocked state with no owners.
If this function is called to release a write lock for this read-
write lock object, the read-write lock object shall be put in the
unlocked state.
If there are threads blocked on the lock when it becomes
available, the scheduling policy shall determine which thread(s)
shall acquire the lock. If the Thread Execution Scheduling option
is supported, when threads executing with the scheduling policies
SCHED_FIFO, SCHED_RR, or SCHED_SPORADIC are waiting on the lock,
they shall acquire the lock in priority order when the lock
becomes available. For equal priority threads, write locks shall
take precedence over read locks. If the Thread Execution
Scheduling option is not supported, it is implementation-defined
whether write locks take precedence over read locks.
Results are undefined if this function is called with an
uninitialized read-write lock.
If successful, the pthread_rwlock_unlock() function shall return
zero; otherwise, an error number shall be returned to indicate the
error.
The pthread_rwlock_unlock() function shall not return an error
code of [EINTR].
The following sections are informative.
None.
None.
If an implementation detects that the value specified by the
rwlock argument to pthread_rwlock_unlock() does not refer to an
initialized read-write lock object, it is recommended that the
function should fail and report an [EINVAL] error.
If an implementation detects that the value specified by the
rwlock argument to pthread_rwlock_unlock() refers to a read-write
lock object for which the current thread does not hold a lock, it
is recommended that the function should fail and report an [EPERM]
error.
None.
pthread_rwlock_destroy(3p), pthread_rwlock_rdlock(3p),
pthread_rwlock_timedrdlock(3p), pthread_rwlock_timedwrlock(3p),
pthread_rwlock_trywrlock(3p)
The Base Definitions volume of POSIX.1‐2017, Section 4.12, Memory
Synchronization, pthread.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics Engineers,
Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard,
the original IEEE and The Open Group Standard is the referee
document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 PTHREAD...K_UNLOCK(3P)
Pages that refer to this page: pthread.h(0p), pthread_rwlock_destroy(3p), pthread_rwlock_rdlock(3p), pthread_rwlock_timedrdlock(3p), pthread_rwlock_timedwrlock(3p), pthread_rwlock_trywrlock(3p)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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