Originální popis anglicky: 
pthread_spin_unlock - unlock a spin lock object ( 
ADVANCED REALTIME
  THREADS)
Návod, kniha: POSIX Programmer's Manual
#include <pthread.h>
 
 
int pthread_spin_unlock(pthread_spinlock_t * 
lock);
   
 
The 
pthread_spin_unlock() function shall release the spin lock referenced
  by 
lock which was locked via the 
pthread_spin_lock() or
  
pthread_spin_trylock() functions. The results are undefined if the lock
  is not held by the calling thread. If there are threads spinning on the lock
  when 
pthread_spin_unlock() is called, the lock becomes available and an
  unspecified spinning thread shall acquire the lock.
The results are undefined if this function is called with an uninitialized
  thread spin lock.
Upon successful completion, the 
pthread_spin_unlock() function shall
  return zero; otherwise, an error number shall be returned to indicate the
  error.
The 
pthread_spin_unlock() function may fail if:
  - EINVAL
- An invalid argument was specified.
  - EPERM
- The calling thread does not hold the lock.
      
This function shall not return an error code of [EINTR].
The following sections are informative.
None.
The 
pthread_spin_unlock() function is part of the Spin Locks option and
  need not be provided on all implementations.
None.
None.
pthread_spin_destroy() , 
pthread_spin_lock() , the Base
  Definitions volume of IEEE Std 1003.1-2001,
  
<pthread.h>
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
  .