(ADVANCED REALTIME THREADS)

SYNOPSIS
       #include <pthread.h>

       int pthread_spin_lock(pthread_spinlock_t *lock);
       int pthread_spin_trylock(pthread_spinlock_t *lock);


DESCRIPTION
       The pthread_spin_lock() function shall lock the spin lock referenced by
       lock.  The  calling  thread shall acquire the lock if it is not held by
       another thread. Otherwise, the thread shall spin (that  is,  shall  not
       return from the pthread_spin_lock() call) until the lock becomes avail-
       able.  The results are undefined if the calling thread holds  the  lock
       at the time the call is made. The pthread_spin_trylock() function shall
       lock the spin lock referenced by lock if it is not held by any  thread.
       Otherwise, the function shall fail.

       The  results  are undefined if any of these functions is called with an
       uninitialized spin lock.

RETURN VALUE
       Upon successful completion, these functions shall return  zero;  other-
       wise, an error number shall be returned to indicate the error.

ERRORS
       These functions may fail if:

       EINVAL The  value  specified  by  lock does not refer to an initialized
              spin lock object.


       The pthread_spin_lock() function may fail if:

       EDEADLK
              The calling thread already holds the lock.


       The pthread_spin_trylock() function shall fail if:

       EBUSY  A thread currently holds the lock.


       These functions shall not return an error code of [EINTR].

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       Applications using this function may be subject to priority  inversion,
       as  discussed  in  the Base Definitions volume of IEEE Std 1003.1-2001,

SEE ALSO
       pthread_spin_destroy() , pthread_spin_unlock() , 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 original Standard can be  obtained  online
       at http://www.opengroup.org/unix/online.html .