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/* rwsem-spinlock.h: fallback C implementation
*
* Copyright (c) 2001 David Howells (dhowells@redhat.com).
* - Derived partially from ideas by Andrea Arcangeli <andrea@suse.de>
* - Derived also from comments by Linus
*/
#ifndef _LINUX_RWSEM_SPINLOCK_H
#define _LINUX_RWSEM_SPINLOCK_H
#ifndef _LINUX_RWSEM_H
#error "please don't include linux/rwsem-spinlock.h directly, use linux/rwsem.h instead"
#endif
#include <linux/spinlock.h>
#include <linux/list.h>
#ifdef __KERNEL__
#include <linux/types.h>
struct rwsem_waiter;
/*
* the rw-semaphore definition
* - if activity is 0 then there are no active readers or writers
* - if activity is +ve then that is the number of active readers
* - if activity is -1 then there is one active writer
* - if wait_list is not empty, then there are processes waiting for the semaphore
*/
struct rw_semaphore {
__s32 activity;
spinlock_t wait_lock;
struct list_head wait_list;
#if RWSEM_DEBUG
int debug;
#endif
};
/*
* initialisation
*/
#if RWSEM_DEBUG
#define __RWSEM_DEBUG_INIT , 0
#else
#define __RWSEM_DEBUG_INIT /* */
#endif
#define __RWSEM_INITIALIZER(name) \
{ 0, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __RWSEM_DEBUG_INIT }
#define DECLARE_RWSEM(name) \
struct rw_semaphore name = __RWSEM_INITIALIZER(name)
extern void FASTCALL(init_rwsem(struct rw_semaphore *sem));
extern void FASTCALL(__down_read(struct rw_semaphore *sem));
extern int FASTCALL(__down_read_trylock(struct rw_semaphore *sem));
extern void FASTCALL(__down_write(struct rw_semaphore *sem));
extern int FASTCALL(__down_write_trylock(struct rw_semaphore *sem));
extern void FASTCALL(__up_read(struct rw_semaphore *sem));
extern void FASTCALL(__up_write(struct rw_semaphore *sem));
extern void FASTCALL(__downgrade_write(struct rw_semaphore *sem));
static inline int rwsem_is_locked(struct rw_semaphore *sem)
{
return (sem->activity != 0);
}
#endif /* __KERNEL__ */
#endif /* _LINUX_RWSEM_SPINLOCK_H */
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