[mirror_ubuntu-artful-kernel.git] / include / linux / osq_lock.h

#ifndef __LINUX_OSQ_LOCK_H
#define __LINUX_OSQ_LOCK_H

/*
 * An MCS like lock especially tailored for optimistic spinning for sleeping
 * lock implementations (mutex, rwsem, etc).
 */

#define OSQ_UNLOCKED_VAL (0)

struct optimistic_spin_queue {
	/*
	 * Stores an encoded value of the CPU # of the tail node in the queue.
	 * If the queue is empty, then it's set to OSQ_UNLOCKED_VAL.
	 */
	atomic_t tail;
};

/* Init macro and function. */
#define OSQ_LOCK_UNLOCKED { ATOMIC_INIT(OSQ_UNLOCKED_VAL) }

static inline void osq_lock_init(struct optimistic_spin_queue *lock)
{
	atomic_set(&lock->tail, OSQ_UNLOCKED_VAL);
}

#endif
Commit	Line	Data
90631822 JL	1	#ifndef __LINUX_OSQ_LOCK_H
	2	#define __LINUX_OSQ_LOCK_H
	3
	4	/*
	5	* An MCS like lock especially tailored for optimistic spinning for sleeping
	6	* lock implementations (mutex, rwsem, etc).
	7	*/
	8
	9	#define OSQ_UNLOCKED_VAL (0)
	10
	11	struct optimistic_spin_queue {
	12	/*
	13	* Stores an encoded value of the CPU # of the tail node in the queue.
	14	* If the queue is empty, then it's set to OSQ_UNLOCKED_VAL.
	15	*/
	16	atomic_t tail;
	17	};
	18
4d9d951e JL	19	/* Init macro and function. */
	20	#define OSQ_LOCK_UNLOCKED { ATOMIC_INIT(OSQ_UNLOCKED_VAL) }
	21
	22	static inline void osq_lock_init(struct optimistic_spin_queue *lock)
	23	{
	24	atomic_set(&lock->tail, OSQ_UNLOCKED_VAL);
	25	}
	26
90631822	27	#endif