3  * Queue read/write lock
22 #define	_QW_LOCKED	0x0ff		/* A writer holds the lock */
30 extern void queued_read_lock_slowpath(struct qrwlock *lock);
31 extern void queued_write_lock_slowpath(struct qrwlock *lock);
34  * queued_read_trylock - try to acquire read lock of a queue rwlock
35  * @lock : Pointer to queue rwlock structure
36  * Return: 1 if lock acquired, 0 if failed
38 static inline int queued_read_trylock(struct qrwlock *lock)  in queued_read_trylock()  argument
42 	cnts = atomic_read(&lock->cnts);  in queued_read_trylock()
44 		cnts = (u32)atomic_add_return_acquire(_QR_BIAS, &lock->cnts);  in queued_read_trylock()
47 		atomic_sub(_QR_BIAS, &lock->cnts);  in queued_read_trylock()
53  * queued_write_trylock - try to acquire write lock of a queue rwlock
54  * @lock : Pointer to queue rwlock structure
55  * Return: 1 if lock acquired, 0 if failed
57 static inline int queued_write_trylock(struct qrwlock *lock)  in queued_write_trylock()  argument
61 	cnts = atomic_read(&lock->cnts);  in queued_write_trylock()
65 	return likely(atomic_try_cmpxchg_acquire(&lock->cnts, &cnts,  in queued_write_trylock()
69  * queued_read_lock - acquire read lock of a queue rwlock
70  * @lock: Pointer to queue rwlock structure
72 static inline void queued_read_lock(struct qrwlock *lock)  in queued_read_lock()  argument
76 	cnts = atomic_add_return_acquire(_QR_BIAS, &lock->cnts);  in queued_read_lock()
81 	queued_read_lock_slowpath(lock);  in queued_read_lock()
85  * queued_write_lock - acquire write lock of a queue rwlock
86  * @lock : Pointer to queue rwlock structure
88 static inline void queued_write_lock(struct qrwlock *lock)  in queued_write_lock()  argument
91 	/* Optimize for the unfair lock case where the fair flag is 0. */  in queued_write_lock()
92 	if (likely(atomic_try_cmpxchg_acquire(&lock->cnts, &cnts, _QW_LOCKED)))  in queued_write_lock()
95 	queued_write_lock_slowpath(lock);  in queued_write_lock()
99  * queued_read_unlock - release read lock of a queue rwlock
100  * @lock : Pointer to queue rwlock structure
102 static inline void queued_read_unlock(struct qrwlock *lock)  in queued_read_unlock()  argument
107 	(void)atomic_sub_return_release(_QR_BIAS, &lock->cnts);  in queued_read_unlock()
111  * queued_write_unlock - release write lock of a queue rwlock
112  * @lock : Pointer to queue rwlock structure
114 static inline void queued_write_unlock(struct qrwlock *lock)  in queued_write_unlock()  argument
116 	smp_store_release(&lock->wlocked, 0);  in queued_write_unlock()