rw_unlock(3synch)                                  rw_unlock(3synch)


       NAME
             rw_unlock - release a reader-writer lock

       SYNOPSIS
             cc [options] -Kthread file
             #include <synch.h>
             int rw_unlock(rwlock_t *lock);

          Parameters
             lock  pointer to the lock to be released

       DESCRIPTION
             rw_unlock releases a reader-writer lock previously acquired by
             rw_rdlock, rw_wrlock, rw_tryrdlock, or rw_trywrlock.  The
             behavior differs according to whether the caller is a reader
             or a writer:

                   When a writer calls rw_unlock, the lock is unlocked.

                   When a reader calls rw_unlock, the reader count is
                   decremented.  If the reader count is zero, rw_unlock
                   unlocks the lock, otherwise, the lock is not unlocked.

             When rw_unlock unlocks the lock, the first waiter (reader or
             writer) is activated.

                   If the thread activated is a reader, all subsequent
                   readers are activated (up to the next writer or end of
                   queue) and the count of readers holding the lock is
                   changed to reflect this.

                   If the thread activated is a writer, no other threads
                   are activated and the lock is marked as being held by a
                   writer.

             lock must previously have been initialized (see rwlock_init).

          Return Values
             rw_unlock returns zero for success and an error number for
             failure, as described below.

          Errors
             If any of the following conditions is detected, rw_unlock
             fails and returns the corresponding value:




                           Copyright 1994 Novell, Inc.               Page 1

      rw_unlock(3synch)                                  rw_unlock(3synch)


            EINVAL   Invalid argument specified.

            ENOLCK   lock is not locked.

      REFERENCES
            rwlock(3synch), rwlock_destroy(3synch), rwlock_init(3synch),
            rw_rdlock(3synch), rw_tryrdlock(3synch), rw_trywrlock(3synch),
            rw_wrlock(3synch), synch(3synch)








































                          Copyright 1994 Novell, Inc.               Page 2