mutex_lock(3synch)                                mutex_lock(3synch)


       NAME
             mutex_lock - lock a mutex

       SYNOPSIS
             cc [options] -Kthread file
             #include <synch.h>
             int mutex_lock(mutex_t *mutex);

          Parameters
             mutex  pointer to mutex to be locked

       DESCRIPTION
             mutex_lock locks the mutual exclusion lock (mutex) pointed to
             by mutex.  If mutex is locked, the calling thread is blocked
             until mutex becomes available.  When mutex_lock returns
             successfully, the caller has locked mutex.

             mutex must previously have been initialized, either by
             mutex_init, or statically (see mutex_init).

             From the point of view of the caller, mutex_lock is atomic:
             even if interrupted by a signal or forkall [see fork(2)],
             mutex_lock will not return until it holds the locked mutex.
             As a consequence, if mutex_lock is interrupted, an error
             indication such as EINTR is never returned to the caller.

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

          Errors
             If any of the following conditions is detected, mutex_lock
             returns the corresponding value:

             EINVAL   Invalid argument specified.

       USAGE
             Mutexes acquired with mutex_lock should be released with
             mutex_unlock.

          Warnings
             If a thread exits while holding a mutex, the mutex will not be
             unlocked, and other threads waiting for the mutex will wait
             forever.  Similarly, if a process exits while holding a
             USYNC_PROCESS mutex, the mutex will not be unlocked, and other
             processes or threads waiting for the mutex will wait forever.


                           Copyright 1994 Novell, Inc.               Page 1

      mutex_lock(3synch)                                mutex_lock(3synch)


      REFERENCES
            fork(2), mutex(3synch), mutex_destroy(3synch),
            mutex_init(3synch), mutex_trylock(3synch),
            mutex_unlock(3synch), synch(3synch)












































                          Copyright 1994 Novell, Inc.               Page 2