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_lock, pthread_spin_trylock - lock a spin lock object (ADVANCED REALTIME THREADS)

#### SYNOPSIS

> ``[THR SPI] #include <pthread.h>
> int pthread_spin_lock(pthread_spinlock_t *`lock`);
> int pthread_spin_trylock(pthread_spinlock_t *`lock`);``
> `
> `

#### DESCRIPTION

> The pthread_spin_lock() function shall lock the spin lock referenced by lock. The calling thread shall acquire the lock if it is not held by another thread. Otherwise, the thread shall spin (that is, shall not return from the pthread_spin_lock() call) until the lock becomes available. The results are undefined if the calling thread holds the lock at the time the call is made. The pthread_spin_trylock() function shall lock the spin lock referenced by lock if it is not held by any thread. Otherwise, the function shall fail.

> The results are undefined if any of these functions is called with an uninitialized spin lock.

#### 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:

> [EINVAL]
>   The value specified by lock does not refer to an initialized spin lock object.

> The pthread_spin_lock() function may fail if:

> [EDEADLK]
>   A deadlock condition was detected or the calling thread already holds the lock.

> The pthread_spin_trylock() function shall fail if:

> [EBUSY]
>   A thread currently holds the lock.

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

The following sections are informative.

#### EXAMPLES

> None.

#### APPLICATION USAGE

> Applications using this function may be subject to priority inversion, as discussed in the Base Definitions volume of IEEE Std 1003.1-2001, Section 3.285, Priority Inversion.

> The pthread_spin_lock() and pthread_spin_trylock() 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_destroy(), 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.

> IEEE Std 1003.1-2001/Cor 2-2004, item XSH/TC2/D6/107 is applied, updating the ERRORS section so that the [EDEADLK] error includes detection of a deadlock condition.

End of informative text.

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