Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/* rwsem-spinlock.h: fallback C implementation
2 *
3 * Copyright (c) 2001 David Howells (dhowells@redhat.com).
4 * - Derived partially from ideas by Andrea Arcangeli <andrea@suse.de>
5 * - Derived also from comments by Linus
6 */
7
8#ifndef _LINUX_RWSEM_SPINLOCK_H
9#define _LINUX_RWSEM_SPINLOCK_H
10
11#ifndef _LINUX_RWSEM_H
12#error "please don't include linux/rwsem-spinlock.h directly, use linux/rwsem.h instead"
13#endif
14
15#include <linux/spinlock.h>
16#include <linux/list.h>
17
18#ifdef __KERNEL__
19
20#include <linux/types.h>
21
22struct rwsem_waiter;
23
24/*
25 * the rw-semaphore definition
26 * - if activity is 0 then there are no active readers or writers
27 * - if activity is +ve then that is the number of active readers
28 * - if activity is -1 then there is one active writer
29 * - if wait_list is not empty, then there are processes waiting for the semaphore
30 */
31struct rw_semaphore {
32 __s32 activity;
33 spinlock_t wait_lock;
34 struct list_head wait_list;
35#if RWSEM_DEBUG
36 int debug;
37#endif
38};
39
40/*
41 * initialisation
42 */
43#if RWSEM_DEBUG
44#define __RWSEM_DEBUG_INIT , 0
45#else
46#define __RWSEM_DEBUG_INIT /* */
47#endif
48
49#define __RWSEM_INITIALIZER(name) \
50{ 0, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __RWSEM_DEBUG_INIT }
51
52#define DECLARE_RWSEM(name) \
53 struct rw_semaphore name = __RWSEM_INITIALIZER(name)
54
55extern void FASTCALL(init_rwsem(struct rw_semaphore *sem));
56extern void FASTCALL(__down_read(struct rw_semaphore *sem));
57extern int FASTCALL(__down_read_trylock(struct rw_semaphore *sem));
58extern void FASTCALL(__down_write(struct rw_semaphore *sem));
59extern int FASTCALL(__down_write_trylock(struct rw_semaphore *sem));
60extern void FASTCALL(__up_read(struct rw_semaphore *sem));
61extern void FASTCALL(__up_write(struct rw_semaphore *sem));
62extern void FASTCALL(__downgrade_write(struct rw_semaphore *sem));
63
64#endif /* __KERNEL__ */
65#endif /* _LINUX_RWSEM_SPINLOCK_H */