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PTHREAD_RWLOCK_UNLOCK(3P)  POSIX Programmer's Manual PTHREAD_RWLOCK_UNLOCK(3P)

PROLOG
       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.
NAME
       pthread_rwlock_unlock - unlock a read-write lock object
SYNOPSIS
       #include <pthread.h>
       int pthread_rwlock_unlock(pthread_rwlock_t *rwlock);

DESCRIPTION
       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  implementa-
       tion-defined whether write locks take precedence over read locks.
       Results  are  undefined  if  any  of these functions are called with an
       uninitialized read-write lock.
RETURN VALUE
       If successful, the pthread_rwlock_unlock() function shall return  zero;
       otherwise, an error number shall be returned to indicate the error.
ERRORS
       The pthread_rwlock_unlock() function may fail if:
       EINVAL The  value  specified by rwlock does not refer to an initialized
              read-write lock object.
       EPERM  The current thread does not hold a lock on the read-write lock.

       The pthread_rwlock_unlock() function shall not return an error code  of
       [EINTR].
       The following sections are informative.
EXAMPLES
       None.
APPLICATION USAGE
       None.
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       pthread_rwlock_destroy(), pthread_rwlock_rdlock(), pthread_rwlock_time-
       drdlock(),  pthread_rwlock_timedwrlock(),   pthread_rwlock_tryrdlock(),
       pthread_rwlock_trywrlock(),  pthread_rwlock_wrlock(),  the Base Defini-
       tions volume of IEEE Std 1003.1-2001, <pthread.h>
COPYRIGHT
       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  Issue  6,  Copyright  (C) 2001-2003 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 .

IEEE/The Open Group                  2003            PTHREAD_RWLOCK_UNLOCK(3P)