/sys$common/syshlp/helplib.hlb DCE_THREADS, Application Routines, pthread_mutex_unlock  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  NAME

      pthread_mutex_unlock - Unlocks a mutex

  SYNOPSIS

      #include <pthread.h>

      int pthread_mutex_unlock( pthread_mutex_t *mutex );

  PARAMETERS

      mutex                Mutex that is unlocked.

  DESCRIPTION

  The pthread_mutex_unlock() routine unlocks a mutex. If no threads are
  waiting for the mutex, the mutex unlocks with no current owner. If one
  or more threads are waiting to lock the specified mutex, this routine
  causes one thread to return from its call to pthread_mutex_lock(). The
  scheduling policy is used to determine which thread acquires the mutex.
  For the SCHED_FIFO and  SCHED_RR policies, a blocked thread is chosen in
  priority order.

  The results of calling this routine are unpredictable if the mutex
  specified in mutex is unlocked. The results of calling this routine are
  also unpredictable if the mutex specified in mutex is currently owned by
  a thread other than the calling thread.

  RETURN VALUES

  If the function fails, errno may be set to one of the following values:

    Return   Error      Description
    ____________________________________________________________
     0                  Successful completion.

    -1      [EINVAL]    The value specified by mutex is invalid.

  RELATED INFORMATION

      FUNCTIONS:  pthread_mutexattr_setkind_np
                  pthread_mutex_destroy
                  pthread_mutex_init
                  pthread_mutex_lock
                  pthread_mutex_trylock
                  pthread_unlock_global_np