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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/linux/rwsem-spinlock.h
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'include/linux/rwsem-spinlock.h')
-rw-r--r--include/linux/rwsem-spinlock.h65
1 files changed, 65 insertions, 0 deletions
diff --git a/include/linux/rwsem-spinlock.h b/include/linux/rwsem-spinlock.h
new file mode 100644
index 000000000000..b52a2af25f1f
--- /dev/null
+++ b/include/linux/rwsem-spinlock.h
@@ -0,0 +1,65 @@
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 */