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- #ifndef _ASM_GENERIC_RWSEM_H
- #define _ASM_GENERIC_RWSEM_H
- #ifndef _LINUX_RWSEM_H
- #error "Please don't include <asm/rwsem.h> directly, use <linux/rwsem.h> instead."
- #endif
- #ifdef __KERNEL__
- #ifdef CONFIG_64BIT
- # define RWSEM_ACTIVE_MASK 0xffffffffL
- #else
- # define RWSEM_ACTIVE_MASK 0x0000ffffL
- #endif
- #define RWSEM_UNLOCKED_VALUE 0x00000000L
- #define RWSEM_ACTIVE_BIAS 0x00000001L
- #define RWSEM_WAITING_BIAS (-RWSEM_ACTIVE_MASK-1)
- #define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
- #define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
- static inline void __down_read(struct rw_semaphore *sem)
- {
- if (unlikely(atomic_long_inc_return_acquire((atomic_long_t *)&sem->count) <= 0))
- rwsem_down_read_failed(sem);
- }
- static inline int __down_read_trylock(struct rw_semaphore *sem)
- {
- long tmp;
- while ((tmp = atomic_long_read(&sem->count)) >= 0) {
- if (tmp == atomic_long_cmpxchg_acquire(&sem->count, tmp,
- tmp + RWSEM_ACTIVE_READ_BIAS)) {
- return 1;
- }
- }
- return 0;
- }
- static inline void __down_write(struct rw_semaphore *sem)
- {
- long tmp;
- tmp = atomic_long_add_return_acquire(RWSEM_ACTIVE_WRITE_BIAS,
- (atomic_long_t *)&sem->count);
- if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS))
- rwsem_down_write_failed(sem);
- }
- static inline int __down_write_killable(struct rw_semaphore *sem)
- {
- long tmp;
- tmp = atomic_long_add_return_acquire(RWSEM_ACTIVE_WRITE_BIAS,
- (atomic_long_t *)&sem->count);
- if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS))
- if (IS_ERR(rwsem_down_write_failed_killable(sem)))
- return -EINTR;
- return 0;
- }
- static inline int __down_write_trylock(struct rw_semaphore *sem)
- {
- long tmp;
- tmp = atomic_long_cmpxchg_acquire(&sem->count, RWSEM_UNLOCKED_VALUE,
- RWSEM_ACTIVE_WRITE_BIAS);
- return tmp == RWSEM_UNLOCKED_VALUE;
- }
- static inline void __up_read(struct rw_semaphore *sem)
- {
- long tmp;
- tmp = atomic_long_dec_return_release((atomic_long_t *)&sem->count);
- if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0))
- rwsem_wake(sem);
- }
- static inline void __up_write(struct rw_semaphore *sem)
- {
- if (unlikely(atomic_long_sub_return_release(RWSEM_ACTIVE_WRITE_BIAS,
- (atomic_long_t *)&sem->count) < 0))
- rwsem_wake(sem);
- }
- static inline void __downgrade_write(struct rw_semaphore *sem)
- {
- long tmp;
-
- tmp = atomic_long_add_return_release(-RWSEM_WAITING_BIAS,
- (atomic_long_t *)&sem->count);
- if (tmp < 0)
- rwsem_downgrade_wake(sem);
- }
- #endif
- #endif
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