Details | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 422 | giacomo | 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 | |||
| 22 | struct 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 | */ |
||
| 31 | struct 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 | |||
| 55 | extern void FASTCALL(init_rwsem(struct rw_semaphore *sem)); |
||
| 56 | extern void FASTCALL(__down_read(struct rw_semaphore *sem)); |
||
| 57 | extern int FASTCALL(__down_read_trylock(struct rw_semaphore *sem)); |
||
| 58 | extern void FASTCALL(__down_write(struct rw_semaphore *sem)); |
||
| 59 | extern int FASTCALL(__down_write_trylock(struct rw_semaphore *sem)); |
||
| 60 | extern void FASTCALL(__up_read(struct rw_semaphore *sem)); |
||
| 61 | extern void FASTCALL(__up_write(struct rw_semaphore *sem)); |
||
| 62 | extern void FASTCALL(__downgrade_write(struct rw_semaphore *sem)); |
||
| 63 | |||
| 64 | #endif /* __KERNEL__ */ |
||
| 65 | #endif /* _LINUX_RWSEM_SPINLOCK_H */ |