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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 422 | giacomo | 1 | /* rwsem-spinlock.h: fallback C implementation |
| 2 | * |
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| 3 | * Copyright (c) 2001 David Howells (dhowells@redhat.com). |
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| 4 | * - Derived partially from ideas by Andrea Arcangeli <andrea@suse.de> |
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| 5 | * - Derived also from comments by Linus |
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| 6 | */ |
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| 7 | |||
| 8 | #ifndef _LINUX_RWSEM_SPINLOCK_H |
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| 9 | #define _LINUX_RWSEM_SPINLOCK_H |
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| 10 | |||
| 11 | #ifndef _LINUX_RWSEM_H |
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| 12 | #error "please don't include linux/rwsem-spinlock.h directly, use linux/rwsem.h instead" |
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| 13 | #endif |
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| 14 | |||
| 15 | #include <linux/spinlock.h> |
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| 16 | #include <linux/list.h> |
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| 17 | |||
| 18 | #ifdef __KERNEL__ |
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| 19 | |||
| 20 | #include <linux/types.h> |
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| 21 | |||
| 22 | struct rwsem_waiter; |
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| 23 | |||
| 24 | /* |
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| 25 | * the rw-semaphore definition |
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| 26 | * - if activity is 0 then there are no active readers or writers |
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| 27 | * - if activity is +ve then that is the number of active readers |
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| 28 | * - if activity is -1 then there is one active writer |
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| 29 | * - if wait_list is not empty, then there are processes waiting for the semaphore |
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| 30 | */ |
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| 31 | struct rw_semaphore { |
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| 32 | __s32 activity; |
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| 33 | spinlock_t wait_lock; |
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| 34 | struct list_head wait_list; |
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| 35 | #if RWSEM_DEBUG |
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| 36 | int debug; |
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| 37 | #endif |
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| 38 | }; |
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| 39 | |||
| 40 | /* |
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| 41 | * initialisation |
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| 42 | */ |
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| 43 | #if RWSEM_DEBUG |
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| 44 | #define __RWSEM_DEBUG_INIT , 0 |
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| 45 | #else |
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| 46 | #define __RWSEM_DEBUG_INIT /* */ |
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| 47 | #endif |
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| 48 | |||
| 49 | #define __RWSEM_INITIALIZER(name) \ |
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| 50 | { 0, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __RWSEM_DEBUG_INIT } |
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| 51 | |||
| 52 | #define DECLARE_RWSEM(name) \ |
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| 53 | struct rw_semaphore name = __RWSEM_INITIALIZER(name) |
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| 54 | |||
| 55 | extern void FASTCALL(init_rwsem(struct rw_semaphore *sem)); |
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| 56 | extern void FASTCALL(__down_read(struct rw_semaphore *sem)); |
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| 57 | extern int FASTCALL(__down_read_trylock(struct rw_semaphore *sem)); |
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| 58 | extern void FASTCALL(__down_write(struct rw_semaphore *sem)); |
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| 59 | extern int FASTCALL(__down_write_trylock(struct rw_semaphore *sem)); |
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| 60 | extern void FASTCALL(__up_read(struct rw_semaphore *sem)); |
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| 61 | extern void FASTCALL(__up_write(struct rw_semaphore *sem)); |
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| 62 | extern void FASTCALL(__downgrade_write(struct rw_semaphore *sem)); |
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| 63 | |||
| 64 | #endif /* __KERNEL__ */ |
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| 65 | #endif /* _LINUX_RWSEM_SPINLOCK_H */ |