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 correspond-
       ing 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_timedrdlock(), pthread_rwlock_timedwrlock(),  pthread_rwlock_tryrdlock(),
       pthread_rwlock_trywrlock(), pthread_rwlock_wrlock(), the Base Definitions 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 Technol-
       ogy -- 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)