root/include/linux/osq_lock.h

INCLUDED FROM

DEFINITIONS

1. osq_lock_init

#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