PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       pthread_spin_destroy, pthread_spin_init — destroy or initialize a spin lock object

SYNOPSIS

       #include <pthread.h>

       int pthread_spin_destroy(pthread_spinlock_t *lock);
       int pthread_spin_init(pthread_spinlock_t *lock, int pshared);

DESCRIPTION

       The  pthread_spin_destroy()  function  shall  destroy the spin lock referenced by lock and
       release any resources used by the lock. The effect  of  subsequent  use  of  the  lock  is
       undefined  until  the  lock  is reinitialized by another call to pthread_spin_init().  The
       results are undefined if pthread_spin_destroy() is called when a thread holds the lock, or
       if this function is called with an uninitialized thread spin lock.

       The  pthread_spin_init()  function  shall  allocate any resources required to use the spin
       lock referenced by lock and initialize the lock to an unlocked state.

       If the Thread Process-Shared Synchronization option is supported and the value of  pshared
       is  PTHREAD_PROCESS_SHARED,  the  implementation shall permit the spin lock to be operated
       upon by any thread that has access to the memory where the spin lock is allocated, even if
       it is allocated in memory that is shared by multiple processes.

       If  the Thread Process-Shared Synchronization option is supported and the value of pshared
       is PTHREAD_PROCESS_PRIVATE, or if the option is not supported, the spin lock shall only be
       operated  upon  by  threads created within the same process as the thread that initialized
       the spin lock. If threads of differing processes attempt to operate on such a  spin  lock,
       the behavior is undefined.

       The  results  are  undefined  if  pthread_spin_init()  is  called  specifying  an  already
       initialized spin lock. The results are undefined if a spin  lock  is  used  without  first
       being initialized.

       If the pthread_spin_init() function fails, the lock is not initialized and the contents of
       lock are undefined.

       Only the object referenced by lock may be used for performing synchronization.

       The result of referring to copies of  that  object  in  calls  to  pthread_spin_destroy(),
       pthread_spin_lock(), pthread_spin_trylock(), or pthread_spin_unlock() is undefined.

RETURN VALUE

       Upon  successful completion, these functions shall return zero; otherwise, an error number
       shall be returned to indicate the error.

ERRORS

       The pthread_spin_init() function shall fail if:

       EAGAIN The system lacks the necessary resources to initialize another spin lock.

       ENOMEM Insufficient memory exists to initialize the lock.

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

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       If  an  implementation  detects  that  the  value  specified  by  the  lock  argument   to
       pthread_spin_destroy()  does  not  refer  to  an  initialized  spin  lock  object,  it  is
       recommended that the function should fail and report an [EINVAL] error.

       If  an  implementation  detects  that  the  value  specified  by  the  lock  argument   to
       pthread_spin_destroy()  or  pthread_spin_init()  refers  to  a locked spin lock object, or
       detects that the value specified by the lock argument to pthread_spin_init() refers to  an
       already  initialized spin lock object, it is recommended that the function should fail and
       report an [EBUSY] error.

FUTURE DIRECTIONS

       None.

SEE ALSO

       pthread_spin_lock(), pthread_spin_unlock()

       The Base Definitions volume of POSIX.1‐2008, <pthread.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2013  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013  by  the
       Institute  of  Electrical  and  Electronics  Engineers,  Inc and The Open Group.  (This is
       POSIX.1-2008 with the  2013  Technical  Corrigendum  1  applied.)  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.unix.org/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .