/* * This file is subject to the terms and conditions of the GNU General Public * License.  See the file "COPYING" in the main directory of this archive * for more details. * * Copyright (C) 1996  Linus Torvalds * Copyright (C) 1998, 99, 2000, 01, 04  Ralf Baechle * Copyright (C) 1999, 2000, 01  Silicon Graphics, Inc. * Copyright (C) 2000, 01 MIPS Technologies, Inc. * * In all honesty, little of the old MIPS code left - the PPC64 variant was * just looking nice and portable so I ripped it.  Credits to whoever wrote * it. */#ifndef __ASM_SEMAPHORE_H#define __ASM_SEMAPHORE_H /* * Remove spinlock-based RW semaphores; RW semaphore definitions are * now in rwsem.h and we use the generic lib/rwsem.c implementation. * Rework semaphores to use atomic_dec_if_positive. * -- Paul Mackerras (paulus@samba.org) */ #ifdef __KERNEL__ #include <asm/atomic.h>#include <asm/system.h>#include <linux/wait.h>#include <linux/rwsem.h> struct semaphore {	/*	 * Note that any negative value of count is equivalent to 0,	 * but additionally indicates that some process(es) might be	 * sleeping on `wait'.	 */	atomic_t count;	wait_queue_head_t wait;}; #define __SEMAPHORE_INITIALIZER(name, n)				\{									\	.count		= ATOMIC_INIT(n),				\	.wait		= __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)	\} #define __DECLARE_SEMAPHORE_GENERIC(name, count) \	struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) #define DECLARE_MUTEX(name)		__DECLARE_SEMAPHORE_GENERIC(name, 1)#define DECLARE_MUTEX_LOCKED(name)	__DECLARE_SEMAPHORE_GENERIC(name, 0) static inline void sema_init (struct semaphore *sem, int val){	atomic_set(&sem->count, val);	init_waitqueue_head(&sem->wait);} static inline void init_MUTEX (struct semaphore *sem){	sema_init(sem, 1);} static inline void init_MUTEX_LOCKED (struct semaphore *sem){	sema_init(sem, 0);} extern void __down(struct semaphore * sem);extern int  __down_interruptible(struct semaphore * sem);extern void __up(struct semaphore * sem); static inline void down(struct semaphore * sem){	might_sleep(); 	/*	 * Try to get the semaphore, take the slow path if we fail.	 */	if (unlikely(atomic_dec_return(&sem->count) < 0))		__down(sem);} static inline int down_interruptible(struct semaphore * sem){	int ret = 0; 	might_sleep(); 	if (unlikely(atomic_dec_return(&sem->count) < 0))		ret = __down_interruptible(sem);	return ret;} static inline int down_trylock(struct semaphore * sem){	return atomic_dec_if_positive(&sem->count) < 0;} static inline void up(struct semaphore * sem){	if (unlikely(atomic_inc_return(&sem->count) <= 0))		__up(sem);} #endif /* __KERNEL__ */ #endif /* __ASM_SEMAPHORE_H */