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 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 27 #endif 28