mutex_init(3synch)                                mutex_init(3synch)


       NAME
             mutex_init - initialize a mutex

       SYNOPSIS
             cc [options] -Kthread file
             #include <synch.h>
             int mutex_init(mutex_t *mutex, int type, void *arg);

          Parameters
             mutex  pointer to mutex to be initialized

             type   USYNC_THREAD or USYNC_PROCESS

             arg    NULL (reserved for future use)

       DESCRIPTION
             mutex_init initializes the mutual exclusion lock (mutex)
             pointed to by mutex to be of type type and in the unlocked
             state.  Once initialized, the mutex can be used any number of
             times without being re-initialized.

          mutex Parameter
             mutex points to the mutex to be initialized.

          type Parameter
             type can be set to one of the following values:

             USYNC_THREAD    Initialize the mutex for threads within the
                             current process.

             USYNC_PROCESS   Initialize the mutex for threads across
                             processes.

          arg Parameter
             arg should be set to NULL.  It is not currently used, but is
             reserved for future use.

          Static Mutex Initialization
             A mutex can be initialized statically if its storage is zero-
             filled.  In this case, the mutex is of type USYNC_THREAD, and
             mutex_init need not be called.

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



                           Copyright 1994 Novell, Inc.               Page 1

      mutex_init(3synch)                                mutex_init(3synch)


         Errors
            If any of the following conditions is detected, the contents
            of mutex are unchanged and mutex_init returns the
            corresponding value:

            EINVAL   Invalid type argument specified.

      USAGE
         Warnings
            mutex_init does not examine the mutex argument before
            initializing it.  If mutex_init is called more than once for
            the same mutex, it will overwrite its state.  It is the user's
            responsibility to ensure that mutex_init is only called once
            for each mutex.

            Operations on locks initialized with mutex_init are not
            recursive-a thread can deadlock if it attempts to relock a
            mutex that it already has locked.

      REFERENCES
            mutex(3synch), mutex_destroy(3synch), mutex_lock(3synch),
            mutex_trylock(3synch), mutex_unlock(3synch), synch(3synch)


























                          Copyright 1994 Novell, Inc.               Page 2