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.

       See  Section  2.9.9,  Synchronization  Object  Copies and Alternative Mappings for further
       requirements.

       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.1‐2017, <pthread.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1-2017, Standard for Information Technology -- Portable  Operating  System  Interface
       (POSIX),  The  Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       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 .