2 * linux/include/asm-arm/semaphore.h
4 #ifndef __ASM_ARM_SEMAPHORE_H
5 #define __ASM_ARM_SEMAPHORE_H
7 #include <linux/linkage.h>
8 #include <linux/spinlock.h>
9 #include <linux/wait.h>
11 #include <asm/atomic.h>
12 #include <asm/proc/locks.h>
17 wait_queue_head_t wait
;
24 # define __SEM_DEBUG_INIT(name) \
25 , (long)&(name).__magic
27 # define __SEM_DEBUG_INIT(name)
30 #define __SEMAPHORE_INIT(name,count) \
31 { ATOMIC_INIT(count), 0, \
32 __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
33 __SEM_DEBUG_INIT(name) }
35 #define __MUTEX_INITIALIZER(name) \
36 __SEMAPHORE_INIT(name,1)
38 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
39 struct semaphore name = __SEMAPHORE_INIT(name,count)
41 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
42 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
44 extern inline void sema_init(struct semaphore
*sem
, int val
)
46 atomic_set(&sem
->count
, val
);
48 init_waitqueue_head(&sem
->wait
);
50 sem
->__magic
= (long)&sem
->__magic
;
54 static inline void init_MUTEX(struct semaphore
*sem
)
59 static inline void init_MUTEX_LOCKED(struct semaphore
*sem
)
65 * special register calling convention
67 asmlinkage
void __down_failed(void);
68 asmlinkage
int __down_interruptible_failed(void);
69 asmlinkage
int __down_trylock_failed(void);
70 asmlinkage
void __up_wakeup(void);
72 extern void __down(struct semaphore
* sem
);
73 extern int __down_interruptible(struct semaphore
* sem
);
74 extern int __down_trylock(struct semaphore
* sem
);
75 extern void __up(struct semaphore
* sem
);
78 * This is ugly, but we want the default case to fall through.
79 * "__down" is the actual routine that waits...
81 extern inline void down(struct semaphore
* sem
)
84 CHECK_MAGIC(sem
->__magic
);
87 __down_op(sem
, __down_failed
);
91 * This is ugly, but we want the default case to fall through.
92 * "__down_interruptible" is the actual routine that waits...
94 extern inline int down_interruptible (struct semaphore
* sem
)
97 CHECK_MAGIC(sem
->__magic
);
100 return __down_op_ret(sem
, __down_interruptible_failed
);
103 extern inline int down_trylock(struct semaphore
*sem
)
106 CHECK_MAGIC(sem
->__magic
);
109 return __down_op_ret(sem
, __down_trylock_failed
);
113 * Note! This is subtle. We jump to wake people up only if
114 * the semaphore was negative (== somebody was waiting on it).
115 * The default case (no contention) will result in NO
116 * jumps for both down() and up().
118 extern inline void up(struct semaphore
* sem
)
121 CHECK_MAGIC(sem
->__magic
);
124 __up_op(sem
, __up_wakeup
);
127 /* rw mutexes (should that be mutices? =) -- throw rw
128 * spinlocks and semaphores together, and this is what we
131 * The lock is initialized to BIAS. This way, a writer
132 * subtracts BIAS ands gets 0 for the case of an uncontended
133 * lock. Readers decrement by 1 and see a positive value
134 * when uncontended, negative if there are writers waiting
135 * (in which case it goes to sleep).
137 * In terms of fairness, this should result in the lock
138 * flopping back and forth between readers and writers
143 struct rw_semaphore
{
145 volatile unsigned char write_bias_granted
;
146 volatile unsigned char read_bias_granted
;
147 volatile unsigned char pad1
;
148 volatile unsigned char pad2
;
149 wait_queue_head_t wait
;
150 wait_queue_head_t write_bias_wait
;
159 #define __RWSEM_DEBUG_INIT , ATOMIC_INIT(0), ATOMIC_INIT(0)
161 #define __RWSEM_DEBUG_INIT /* */
164 #define __RWSEM_INITIALIZER(name,count) \
165 { ATOMIC_INIT(count), 0, 0, 0, 0, __WAIT_QUEUE_HEAD_INITIALIZER((name).wait), \
166 __WAIT_QUEUE_HEAD_INITIALIZER((name).write_bias_wait) \
167 __SEM_DEBUG_INIT(name) __RWSEM_DEBUG_INIT }
169 #define __DECLARE_RWSEM_GENERIC(name,count) \
170 struct rw_semaphore name = __RWSEM_INITIALIZER(name,count)
172 #define DECLARE_RWSEM(name) __DECLARE_RWSEM_GENERIC(name,RW_LOCK_BIAS)
173 #define DECLARE_RWSEM_READ_LOCKED(name) __DECLARE_RWSEM_GENERIC(name,RW_LOCK_BIAS-1)
174 #define DECLARE_RWSEM_WRITE_LOCKED(name) __DECLARE_RWSEM_GENERIC(name,0)
176 extern inline void init_rwsem(struct rw_semaphore
*sem
)
178 atomic_set(&sem
->count
, RW_LOCK_BIAS
);
179 sem
->read_bias_granted
= 0;
180 sem
->write_bias_granted
= 0;
181 init_waitqueue_head(&sem
->wait
);
182 init_waitqueue_head(&sem
->write_bias_wait
);
184 sem
->__magic
= (long)&sem
->__magic
;
185 atomic_set(&sem
->readers
, 0);
186 atomic_set(&sem
->writers
, 0);
190 extern struct rw_semaphore
*__down_read_failed(struct rw_semaphore
*sem
);
191 extern struct rw_semaphore
*__down_write_failed(struct rw_semaphore
*sem
);
192 extern struct rw_semaphore
*__rwsem_wake(struct rw_semaphore
*sem
);
194 extern inline void down_read(struct rw_semaphore
*sem
)
197 CHECK_MAGIC(sem
->__magic
);
199 __down_op_read(sem
, __down_read_failed
);
201 if (sem
->write_bias_granted
)
203 if (atomic_read(&sem
->writers
))
205 atomic_inc(&sem
->readers
);
209 extern inline void down_write(struct rw_semaphore
*sem
)
212 CHECK_MAGIC(sem
->__magic
);
214 __down_op_write(sem
, __down_write_failed
);
216 if (atomic_read(&sem
->writers
))
218 if (atomic_read(&sem
->readers
))
220 if (sem
->read_bias_granted
)
222 if (sem
->write_bias_granted
)
224 atomic_inc(&sem
->writers
);
228 extern inline void up_read(struct rw_semaphore
*sem
)
231 if (sem
->write_bias_granted
)
233 if (atomic_read(&sem
->writers
))
235 atomic_dec(&sem
->readers
);
237 __up_op_read(sem
, __rwsem_wake
);
240 extern inline void up_write(struct rw_semaphore
*sem
)
243 if (sem
->read_bias_granted
)
245 if (sem
->write_bias_granted
)
247 if (atomic_read(&sem
->readers
))
249 if (atomic_read(&sem
->writers
) != 1)
251 atomic_dec(&sem
->writers
);
253 __up_op_write(sem
, __rwsem_wake
);