futex.c File Reference

This source file contains the implementation of _Futex_Wait() and _Futex_Wake(). More...

#include <sys/lock.h>
#include <errno.h>
#include <rtems/score/atomic.h>
#include <rtems/score/chainimpl.h>
#include <rtems/score/threadimpl.h>
#include <rtems/score/threadqimpl.h>

Data Structures
struct	Futex_Control
struct	Futex_Context

Macros
#define	FUTEX_TQ_OPERATIONS   &_Thread_queue_Operations_FIFO

Functions
	RTEMS_STATIC_ASSERT (offsetof(Futex_Control, Queue)==offsetof(struct _Futex_Control, _Queue), FUTEX_CONTROL_QUEUE)
	RTEMS_STATIC_ASSERT (sizeof(Futex_Control)==sizeof(struct _Futex_Control), FUTEX_CONTROL_SIZE)
int	_Futex_Wait (struct _Futex_Control *_futex, int *uaddr, int val)
	Performs the FUTEX_WAIT operation.
int	_Futex_Wake (struct _Futex_Control *_futex, int count)
	Performs the FUTEX_WAKE operation.

Detailed Description

This source file contains the implementation of _Futex_Wait() and _Futex_Wake().

Function Documentation

_Futex_Wait()

int _Futex_Wait	(	struct _Futex_Control *	_futex,
		int *	uaddr,
		int	val )

Performs the FUTEX_WAIT operation.

Parameters

[in,out]	_futex	is the futex object.
[in]	uaddr	is the address to the futex state.
	val	is the expected futex state value.

Return values

0	Returns zero if the futex state is equal to the expected value. In this case the calling thread is enqueued on the thread queue of the futex object.
EAGAIN	Returns EAGAIN if the futex state is not equal to the expected value.

_Futex_Wake()

int _Futex_Wake	(	struct _Futex_Control *	_futex,
		int	count )

Performs the FUTEX_WAKE operation.

Parameters

[in,out]	_futex	is the futex object.
	count	is the maximum count of threads to wake up.

Returns

Returns the count of woken up threads.