| #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). |
| struct optimistic_spin_node { |
| struct optimistic_spin_node *next, *prev; |
| int locked; /* 1 if lock acquired */ |
| int cpu; /* encoded CPU # + 1 value */ |
| 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. |
| #define OSQ_UNLOCKED_VAL (0) |
| /* 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); |
| extern bool osq_lock(struct optimistic_spin_queue *lock); |
| extern void osq_unlock(struct optimistic_spin_queue *lock); |
| static inline bool osq_is_locked(struct optimistic_spin_queue *lock) |
| return atomic_read(&lock->tail) != OSQ_UNLOCKED_VAL; |