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 */ 8struct optimistic_spin_node { 9 struct optimistic_spin_node *next, *prev; 10 int locked; /* 1 if lock acquired */ 11 int cpu; /* encoded CPU # + 1 value */ 12}; 13 14struct optimistic_spin_queue { 15 /* 16 * Stores an encoded value of the CPU # of the tail node in the queue. 17 * If the queue is empty, then it's set to OSQ_UNLOCKED_VAL. 18 */ 19 atomic_t tail; 20}; 21 22#define OSQ_UNLOCKED_VAL (0) 23 24/* Init macro and function. */ 25#define OSQ_LOCK_UNLOCKED { ATOMIC_INIT(OSQ_UNLOCKED_VAL) } 26 27static inline void osq_lock_init(struct optimistic_spin_queue *lock) 28{ 29 atomic_set(&lock->tail, OSQ_UNLOCKED_VAL); 30} 31 32extern bool osq_lock(struct optimistic_spin_queue *lock); 33extern void osq_unlock(struct optimistic_spin_queue *lock); 34 35#endif 36