46 lines
1.5 KiB
C
46 lines
1.5 KiB
C
|
/* 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
|
||
|
|
|
||
|
|
#ifdef __KERNEL__
|
||
|
|
/*
|
||
|
|
* 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;
|
||
|
|
raw_spinlock_t wait_lock;
|
||
|
|
struct list_head wait_list;
|
||
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
||
|
|
struct lockdep_map dep_map;
|
||
|
|
#endif
|
||
|
|
};
|
||
|
|
|
||
|
|
#define RWSEM_UNLOCKED_VALUE 0x00000000
|
||
|
|
|
||
|
|
extern void __down_read(struct rw_semaphore *sem);
|
||
|
|
extern int __down_read_trylock(struct rw_semaphore *sem);
|
||
|
|
extern void __down_write(struct rw_semaphore *sem);
|
||
|
|
extern void __down_write_nested(struct rw_semaphore *sem, int subclass);
|
||
|
|
extern int __down_write_trylock(struct rw_semaphore *sem);
|
||
|
|
extern void __up_read(struct rw_semaphore *sem);
|
||
|
|
extern void __up_write(struct rw_semaphore *sem);
|
||
|
|
extern void __downgrade_write(struct rw_semaphore *sem);
|
||
|
|
extern int rwsem_is_locked(struct rw_semaphore *sem);
|
||
|
|
|
||
|
|
#endif /* __KERNEL__ */
|
||
|
|
#endif /* _LINUX_RWSEM_SPINLOCK_H */
|