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review.evervolv.com / android_kernel_oneplus_sm8150 / 34c8e3d2bb901b2920d2a8930c0de82e7fefac76 / . / include / linux / rwsem-spinlock.h
blob: 34701241b67395bd58f7a4b262b6dcceb0e4f74f [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]15#ifdef __KERNEL__
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]16/*
17 * the rw-semaphore definition
18 * - if activity is 0 then there are no active readers or writers
19 * - if activity is +ve then that is the number of active readers
20 * - if activity is -1 then there is one active writer
21 * - if wait_list is not empty, then there are processes waiting for the semaphore
22 */
23struct rw_semaphore {
24 __s32 activity;
25 spinlock_t wait_lock;
26 struct list_head wait_list;
Ingo Molnar4ea21762006-07-03 00:24:53 -0700[diff] [blame]27#ifdef CONFIG_DEBUG_LOCK_ALLOC
28 struct lockdep_map dep_map;
29#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]30};
31
Thomas Gleixner12249b32011-01-26 20:06:00 +0000[diff] [blame]32#define RWSEM_UNLOCKED_VALUE 0x00000000
Ingo Molnar4ea21762006-07-03 00:24:53 -0700[diff] [blame]33
Harvey Harrisonb3c97522008-02-13 15:03:15 -0800[diff] [blame]34extern void __down_read(struct rw_semaphore *sem);
35extern int __down_read_trylock(struct rw_semaphore *sem);
36extern void __down_write(struct rw_semaphore *sem);
37extern void __down_write_nested(struct rw_semaphore *sem, int subclass);
38extern int __down_write_trylock(struct rw_semaphore *sem);
39extern void __up_read(struct rw_semaphore *sem);
40extern void __up_write(struct rw_semaphore *sem);
41extern void __downgrade_write(struct rw_semaphore *sem);
Amerigo Wang29671f22009-12-14 18:00:21 -0800[diff] [blame]42extern int rwsem_is_locked(struct rw_semaphore *sem);
Rik Van Rieleb92f4e2005-10-29 18:15:44 -0700[diff] [blame]43
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]44#endif /* __KERNEL__ */
45#endif /* _LINUX_RWSEM_SPINLOCK_H */