3  * Queue read/write lock
24 #define	_QW_LOCKED	0x0ff		/* A writer holds the lock */
32 extern void queued_read_lock_slowpath(struct qrwlock *lock);
33 extern void queued_write_lock_slowpath(struct qrwlock *lock);
36  * queued_read_trylock - try to acquire read lock of a queue rwlock
37  * @lock : Pointer to queue rwlock structure
38  * Return: 1 if lock acquired, 0 if failed
40 static inline int queued_read_trylock(struct qrwlock *lock)  in queued_read_trylock()  argument
44 	cnts = atomic_read(&lock->cnts);  in queued_read_trylock()
46 		cnts = (u32)atomic_add_return_acquire(_QR_BIAS, &lock->cnts);  in queued_read_trylock()
49 		atomic_sub(_QR_BIAS, &lock->cnts);  in queued_read_trylock()
55  * queued_write_trylock - try to acquire write lock of a queue rwlock
56  * @lock : Pointer to queue rwlock structure
57  * Return: 1 if lock acquired, 0 if failed
59 static inline int queued_write_trylock(struct qrwlock *lock)  in queued_write_trylock()  argument
63 	cnts = atomic_read(&lock->cnts);  in queued_write_trylock()
67 	return likely(atomic_try_cmpxchg_acquire(&lock->cnts, &cnts,  in queued_write_trylock()
71  * queued_read_lock - acquire read lock of a queue rwlock
72  * @lock: Pointer to queue rwlock structure
74 static inline void queued_read_lock(struct qrwlock *lock)  in queued_read_lock()  argument
78 	cnts = atomic_add_return_acquire(_QR_BIAS, &lock->cnts);  in queued_read_lock()
83 	queued_read_lock_slowpath(lock);  in queued_read_lock()
87  * queued_write_lock - acquire write lock of a queue rwlock
88  * @lock : Pointer to queue rwlock structure
90 static inline void queued_write_lock(struct qrwlock *lock)  in queued_write_lock()  argument
93 	/* Optimize for the unfair lock case where the fair flag is 0. */  in queued_write_lock()
94 	if (likely(atomic_try_cmpxchg_acquire(&lock->cnts, &cnts, _QW_LOCKED)))  in queued_write_lock()
97 	queued_write_lock_slowpath(lock);  in queued_write_lock()
101  * queued_read_unlock - release read lock of a queue rwlock
102  * @lock : Pointer to queue rwlock structure
104 static inline void queued_read_unlock(struct qrwlock *lock)  in queued_read_unlock()  argument
109 	(void)atomic_sub_return_release(_QR_BIAS, &lock->cnts);  in queued_read_unlock()
113  * queued_write_unlock - release write lock of a queue rwlock
114  * @lock : Pointer to queue rwlock structure
116 static inline void queued_write_unlock(struct qrwlock *lock)  in queued_write_unlock()  argument
118 	smp_store_release(&lock->wlocked, 0);  in queued_write_unlock()
122  * queued_rwlock_is_contended - check if the lock is contended
123  * @lock : Pointer to queue rwlock structure
124  * Return: 1 if lock contended, 0 otherwise
126 static inline int queued_rwlock_is_contended(struct qrwlock *lock)  in queued_rwlock_is_contended()  argument
128 	return arch_spin_is_locked(&lock->wait_lock);  in queued_rwlock_is_contended()