projects / linux-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
1 | /* rwsem.h: R/W semaphores, public interface |
| 2 | * | |
| 3 | * Written by David Howells (dhowells@redhat.com). | |
| 4 | * Derived from asm-i386/semaphore.h | |
| 5 | */ | |
| 6 | ||
| 7 | #ifndef _LINUX_RWSEM_H | |
| 8 | #define _LINUX_RWSEM_H | |
| 9 | ||
| 10 | #include <linux/linkage.h> | |
| 11 | ||
| 12 | #define RWSEM_DEBUG 0 | |
| 13 | ||
| 14 | #ifdef __KERNEL__ | |
| 15 | ||
| 16 | #include <linux/config.h> | |
| 17 | #include <linux/types.h> | |
| 18 | #include <linux/kernel.h> | |
| 19 | #include <asm/system.h> | |
| 20 | #include <asm/atomic.h> | |
| 21 | ||
| 22 | struct rw_semaphore; | |
| 23 | ||
| 24 | #ifdef CONFIG_RWSEM_GENERIC_SPINLOCK | |
| 25 | #include <linux/rwsem-spinlock.h> /* use a generic implementation */ | |
| 26 | #else | |
| 27 | #include <asm/rwsem.h> /* use an arch-specific implementation */ | |
| 28 | #endif | |
| 29 | ||
| 30 | #ifndef rwsemtrace | |
| 31 | #if RWSEM_DEBUG | |
| 32 | extern void FASTCALL(rwsemtrace(struct rw_semaphore *sem, const char *str)); | |
| 33 | #else | |
| 34 | #define rwsemtrace(SEM,FMT) | |
| 35 | #endif | |
| 36 | #endif | |
| 37 | ||
| 38 | /* | |
| 39 | * lock for reading | |
| 40 | */ | |
| 41 | static inline void down_read(struct rw_semaphore *sem) | |
| 42 | { | |
| 43 | might_sleep(); | |
| 44 | rwsemtrace(sem,"Entering down_read"); | |
| 45 | __down_read(sem); | |
| 46 | rwsemtrace(sem,"Leaving down_read"); | |
| 47 | } | |
| 48 | ||
| 49 | /* | |
| 50 | * trylock for reading -- returns 1 if successful, 0 if contention | |
| 51 | */ | |
| 52 | static inline int down_read_trylock(struct rw_semaphore *sem) | |
| 53 | { | |
| 54 | int ret; | |
| 55 | rwsemtrace(sem,"Entering down_read_trylock"); | |
| 56 | ret = __down_read_trylock(sem); | |
| 57 | rwsemtrace(sem,"Leaving down_read_trylock"); | |
| 58 | return ret; | |
| 59 | } | |
| 60 | ||
| 61 | /* | |
| 62 | * lock for writing | |
| 63 | */ | |
| 64 | static inline void down_write(struct rw_semaphore *sem) | |
| 65 | { | |
| 66 | might_sleep(); | |
| 67 | rwsemtrace(sem,"Entering down_write"); | |
| 68 | __down_write(sem); | |
| 69 | rwsemtrace(sem,"Leaving down_write"); | |
| 70 | } | |
| 71 | ||
| 72 | /* | |
| 73 | * trylock for writing -- returns 1 if successful, 0 if contention | |
| 74 | */ | |
| 75 | static inline int down_write_trylock(struct rw_semaphore *sem) | |
| 76 | { | |
| 77 | int ret; | |
| 78 | rwsemtrace(sem,"Entering down_write_trylock"); | |
| 79 | ret = __down_write_trylock(sem); | |
| 80 | rwsemtrace(sem,"Leaving down_write_trylock"); | |
| 81 | return ret; | |
| 82 | } | |
| 83 | ||
| 84 | /* | |
| 85 | * release a read lock | |
| 86 | */ | |
| 87 | static inline void up_read(struct rw_semaphore *sem) | |
| 88 | { | |
| 89 | rwsemtrace(sem,"Entering up_read"); | |
| 90 | __up_read(sem); | |
| 91 | rwsemtrace(sem,"Leaving up_read"); | |
| 92 | } | |
| 93 | ||
| 94 | /* | |
| 95 | * release a write lock | |
| 96 | */ | |
| 97 | static inline void up_write(struct rw_semaphore *sem) | |
| 98 | { | |
| 99 | rwsemtrace(sem,"Entering up_write"); | |
| 100 | __up_write(sem); | |
| 101 | rwsemtrace(sem,"Leaving up_write"); | |
| 102 | } | |
| 103 | ||
| 104 | /* | |
| 105 | * downgrade write lock to read lock | |
| 106 | */ | |
| 107 | static inline void downgrade_write(struct rw_semaphore *sem) | |
| 108 | { | |
| 109 | rwsemtrace(sem,"Entering downgrade_write"); | |
| 110 | __downgrade_write(sem); | |
| 111 | rwsemtrace(sem,"Leaving downgrade_write"); | |
| 112 | } | |
| 113 | ||
| 114 | #endif /* __KERNEL__ */ | |
| 115 | #endif /* _LINUX_RWSEM_H */ |