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16 September 2024, 20:19:31 UTC
Revision 56731b16ce5a9f11cb9496d76e4ffac11987fc85 authored by Brian Keiseler on 12 January 2015, 11:04:12 UTC, committed by Brian Keiseler on 12 January 2015, 11:04:12 UTC 
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Tip revision: 56731b16ce5a9f11cb9496d76e4ffac11987fc85 authored by Brian Keiseler on 12 January 2015, 11:04:12 UTC
Update Copyright
Tip revision: 56731b1
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
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