The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.

#### NAME

> pthread_spin_destroy, pthread_spin_init - destroy or initialize a spin lock object (ADVANCED REALTIME THREADS)

#### SYNOPSIS

> ``[THR SPI] #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.

> [TSH] 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

> These functions may fail if:

> [EBUSY]
>   The implementation has detected an attempt to initialize or destroy a spin lock while it is in use (for example, while being used in a pthread_spin_lock() call) by another thread.
> [EINVAL]
>   The value specified by lock is invalid.

> 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

> The pthread_spin_destroy() and pthread_spin_init() functions are part of the Spin Locks option and need not be provided on all implementations.

#### RATIONALE

> None.

#### FUTURE DIRECTIONS

> None.

#### SEE ALSO

> pthread_spin_lock(), pthread_spin_unlock(), the Base Definitions volume of IEEE Std 1003.1-2001, <pthread.h>

#### CHANGE HISTORY

> First released in Issue 6. Derived from IEEE Std 1003.1j-2000.

> In the SYNOPSIS, the inclusion of <sys/types.h> is no longer required.

End of informative text.

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