projects / mirror_ubuntu-bionic-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
| 1da177e4 LT |
2 | /* rwsem-spinlock.h: fallback C implementation |
| 3 | * | |
| 4 | * Copyright (c) 2001 David Howells (dhowells@redhat.com). | |
| 5 | * - Derived partially from ideas by Andrea Arcangeli <andrea@suse.de> | |
| 6 | * - Derived also from comments by Linus | |
| 7 | */ | |
| 8 | ||
| 9 | #ifndef _LINUX_RWSEM_SPINLOCK_H | |
| 10 | #define _LINUX_RWSEM_SPINLOCK_H | |
| 11 | ||
| 12 | #ifndef _LINUX_RWSEM_H | |
| 13 | #error "please don't include linux/rwsem-spinlock.h directly, use linux/rwsem.h instead" | |
| 14 | #endif | |
| 15 | ||
| 1da177e4 | 16 | #ifdef __KERNEL__ |
| 1da177e4 LT |
17 | /* |
| 18 | * the rw-semaphore definition | |
| 13b9a962 PZ |
19 | * - if count is 0 then there are no active readers or writers |
| 20 | * - if count is +ve then that is the number of active readers | |
| 21 | * - if count is -1 then there is one active writer | |
| 1da177e4 LT |
22 | * - if wait_list is not empty, then there are processes waiting for the semaphore |
| 23 | */ | |
| 24 | struct rw_semaphore { | |
| 13b9a962 | 25 | __s32 count; |
| ddb6c9b5 | 26 | raw_spinlock_t wait_lock; |
| 1da177e4 | 27 | struct list_head wait_list; |
| 4ea2176d IM |
28 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| 29 | struct lockdep_map dep_map; | |
| 30 | #endif | |
| 1da177e4 LT |
31 | }; |
| 32 | ||
| 12249b34 | 33 | #define RWSEM_UNLOCKED_VALUE 0x00000000 |
| 4ea2176d | 34 | |
| b3c97528 | 35 | extern void __down_read(struct rw_semaphore *sem); |
| 0aa1125f | 36 | extern int __must_check __down_read_killable(struct rw_semaphore *sem); |
| b3c97528 HH |
37 | extern int __down_read_trylock(struct rw_semaphore *sem); |
| 38 | extern void __down_write(struct rw_semaphore *sem); | |
| d4799608 | 39 | extern int __must_check __down_write_killable(struct rw_semaphore *sem); |
| b3c97528 HH |
40 | extern int __down_write_trylock(struct rw_semaphore *sem); |
| 41 | extern void __up_read(struct rw_semaphore *sem); | |
| 42 | extern void __up_write(struct rw_semaphore *sem); | |
| 43 | extern void __downgrade_write(struct rw_semaphore *sem); | |
| 29671f22 | 44 | extern int rwsem_is_locked(struct rw_semaphore *sem); |
| eb92f4ef | 45 | |
| 1da177e4 LT |
46 | #endif /* __KERNEL__ */ |
| 47 | #endif /* _LINUX_RWSEM_SPINLOCK_H */ |