This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       Applications using these and related read-write lock functions may be subject to priority  inversion,  as
       discussed in the Base Definitions volume of POSIX.1‐2017, Section3.291, PriorityInversion.

       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 .

IEEE/The Open Group                                   2017                        PTHREAD_RWLOCK_DESTROY(3POSIX)

       The  pthread_rwlock_destroy()  function shall destroy the read-write lock object referenced by rwlock 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_rwlock_init().   An  implementation  may  cause
       pthread_rwlock_destroy() to set the object  referenced  by  rwlock  to  an  invalid  value.  Results  are
       undefined  if  pthread_rwlock_destroy() is called when any thread holds rwlock.  Attempting to destroy an
       uninitialized read-write lock results in undefined behavior.

       The pthread_rwlock_init() function shall allocate any resources  required  to  use  the  read-write  lock
       referenced  by  rwlock  and initializes the lock to an unlocked state with attributes referenced by attr.
       If attr is NULL, the default read-write lock attributes shall be used; the effect is the same as  passing
       the  address  of  a default read-write lock attributes object. Once initialized, the lock can be used any
       number of times without being reinitialized. Results are undefined  if  pthread_rwlock_init()  is  called
       specifying  an  already  initialized  read-write lock. Results are undefined if a read-write lock is used
       without first being initialized.

       If the pthread_rwlock_init() function fails, rwlock shall not be initialized and the contents  of  rwlock
       are undefined.

       See Section2.9.9, SynchronizationObjectCopiesandAlternativeMappings for further requirements.

       In  cases  where default read-write lock attributes are appropriate, the macro PTHREAD_RWLOCK_INITIALIZER
       can be used to initialize read-write locks. The effect shall be equivalent to dynamic initialization by a
       call to pthread_rwlock_init() with the attr parameter specified as NULL, except that no error checks  are
       performed.

       The  behavior  is undefined if the value specified by the attr argument to pthread_rwlock_init() does not
       refer to an initialized read-write lock attributes object.

       The pthread_rwlock_init() function shall fail if:

       EAGAIN The  system  lacked  the  necessary resources (other than memory) to initialize another read-write
              lock.

       ENOMEM Insufficient memory exists to initialize the read-write lock.

       EPERM  The caller does not have the privilege to perform the operation.

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

       Thefollowingsectionsareinformative.

       None.

       None.

       pthread_rwlock_destroy, pthread_rwlock_init — destroy and initialize a read-write lock object

       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.

       If  an implementation detects that the value specified by the rwlock argument to pthread_rwlock_destroy()
       does not refer to an initialized read-write 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 attr argument to pthread_rwlock_init() does
       not refer to an initialized read-write lock attributes object, it is recommended that the function should
       fail and report an [EINVAL] error.

       If an implementation detects that the value specified by the rwlock argument to  pthread_rwlock_destroy()
       or  pthread_rwlock_init()  refers to a locked read-write lock object, or detects that the value specified
       by the rwlock argument to pthread_rwlock_init() refers to an already initialized read-write lock  object,
       it is recommended that the function should fail and report an [EBUSY] error.

       If successful, the  pthread_rwlock_destroy()  and  pthread_rwlock_init()  functions  shall  return  zero;
       otherwise, an error number shall be returned to indicate the error.

pthread_rwlock_rdlock(), pthread_rwlock_timedrdlock(), pthread_rwlock_timedwrlock(),
       pthread_rwlock_trywrlock(), pthread_rwlock_unlock()

       The Base Definitions volume of POSIX.1‐2017, Section3.291, PriorityInversion, <pthread.h>

       #include <pthread.h>

       int pthread_rwlock_destroy(pthread_rwlock_t *rwlock);
       int pthread_rwlock_init(pthread_rwlock_t *restrict rwlock,
           const pthread_rwlockattr_t *restrict attr);
       pthread_rwlock_t rwlock = PTHREAD_RWLOCK_INITIALIZER;