1#ifndef _ASM_POWERPC_SEMAPHORE_H 2#define _ASM_POWERPC_SEMAPHORE_H 3 4/* 5 * Remove spinlock-based RW semaphores; RW semaphore definitions are 6 * now in rwsem.h and we use the generic lib/rwsem.c implementation. 7 * Rework semaphores to use atomic_dec_if_positive. 8 * -- Paul Mackerras (paulus@samba.org) 9 */ 10 11#ifdef __KERNEL__ 12 13#include <asm/atomic.h> 14#include <asm/system.h> 15#include <linux/wait.h> 16#include <linux/rwsem.h> 17 18struct semaphore { 19 /* 20 * Note that any negative value of count is equivalent to 0, 21 * but additionally indicates that some process(es) might be 22 * sleeping on `wait'. 23 */ 24 atomic_t count; 25 wait_queue_head_t wait; 26}; 27 28#define __SEMAPHORE_INITIALIZER(name, n) \ 29{ \ 30 .count = ATOMIC_INIT(n), \ 31 .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \ 32} 33 34#define __DECLARE_SEMAPHORE_GENERIC(name, count) \ 35 struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) 36 37#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1) 38#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name, 0) 39 40static inline void sema_init (struct semaphore *sem, int val) 41{ 42 atomic_set(&sem->count, val); 43 init_waitqueue_head(&sem->wait); 44} 45 46static inline void init_MUTEX (struct semaphore *sem) 47{ 48 sema_init(sem, 1); 49} 50 51static inline void init_MUTEX_LOCKED (struct semaphore *sem) 52{ 53 sema_init(sem, 0); 54} 55 56extern void __down(struct semaphore * sem); 57extern int __down_interruptible(struct semaphore * sem); 58extern void __up(struct semaphore * sem); 59 60static inline void down(struct semaphore * sem) 61{ 62 might_sleep(); 63 64 /* 65 * Try to get the semaphore, take the slow path if we fail. 66 */ 67 if (unlikely(atomic_dec_return(&sem->count) < 0)) 68 __down(sem); 69} 70 71static inline int down_interruptible(struct semaphore * sem) 72{ 73 int ret = 0; 74 75 might_sleep(); 76 77 if (unlikely(atomic_dec_return(&sem->count) < 0)) 78 ret = __down_interruptible(sem); 79 return ret; 80} 81 82static inline int down_trylock(struct semaphore * sem) 83{ 84 return atomic_dec_if_positive(&sem->count) < 0; 85} 86 87static inline void up(struct semaphore * sem) 88{ 89 if (unlikely(atomic_inc_return(&sem->count) <= 0)) 90 __up(sem); 91} 92 93#endif /* __KERNEL__ */ 94 95#endif /* _ASM_POWERPC_SEMAPHORE_H */ 96