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Linux 2.6 - man page for pthread_rwlock_unlock (linux section 3posix)

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

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 Sched-
       uling 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 prior-
       ity 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 sup-
       ported, it is implementation-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 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 orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003			 PTHREAD_RWLOCK_UNLOCK(P)


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