1 #ifndef _PPC_SEMAPHORE_H
2 #define _PPC_SEMAPHORE_H
5 * Swiped from asm-sparc/semaphore.h and modified
6 * -- Cort (cort@cs.nmt.edu)
8 * Stole some rw spinlock-based semaphore stuff from asm-alpha/semaphore.h
9 * -- Ani Joshi (ajoshi@unixbox.com)
11 * Remove spinlock-based RW semaphores; RW semaphore definitions are
12 * now in rwsem.h and we use the generic lib/rwsem.c implementation.
13 * Rework semaphores to use atomic_dec_if_positive.
14 * -- Paul Mackerras (paulus@samba.org)
19 #include <asm/atomic.h>
20 #include <asm/system.h>
21 #include <linux/wait.h>
22 #include <linux/rwsem.h>
26 * Note that any negative value of count is equivalent to 0,
27 * but additionally indicates that some process(es) might be
31 wait_queue_head_t wait;
32 #ifdef WAITQUEUE_DEBUG
37 #ifdef WAITQUEUE_DEBUG
38 # define __SEM_DEBUG_INIT(name) \
39 , (long)&(name).__magic
41 # define __SEM_DEBUG_INIT(name)
44 #define __SEMAPHORE_INITIALIZER(name, count) \
45 { ATOMIC_INIT(count), \
46 __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
47 __SEM_DEBUG_INIT(name) }
49 #define __MUTEX_INITIALIZER(name) \
50 __SEMAPHORE_INITIALIZER(name, 1)
52 #define __DECLARE_SEMAPHORE_GENERIC(name, count) \
53 struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
55 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1)
56 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name, 0)
58 static inline void sema_init (struct semaphore *sem, int val)
60 atomic_set(&sem->count, val);
61 init_waitqueue_head(&sem->wait);
62 #ifdef WAITQUEUE_DEBUG
63 sem->__magic = (long)&sem->__magic;
67 static inline void init_MUTEX (struct semaphore *sem)
72 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
77 extern void __down(struct semaphore * sem);
78 extern int __down_interruptible(struct semaphore * sem);
79 extern void __up(struct semaphore * sem);
81 extern inline void down(struct semaphore * sem)
83 #ifdef WAITQUEUE_DEBUG
84 CHECK_MAGIC(sem->__magic);
89 * Try to get the semaphore, take the slow path if we fail.
91 if (atomic_dec_return(&sem->count) < 0)
96 extern inline int down_interruptible(struct semaphore * sem)
100 #ifdef WAITQUEUE_DEBUG
101 CHECK_MAGIC(sem->__magic);
105 if (atomic_dec_return(&sem->count) < 0)
106 ret = __down_interruptible(sem);
111 extern inline int down_trylock(struct semaphore * sem)
115 #ifdef WAITQUEUE_DEBUG
116 CHECK_MAGIC(sem->__magic);
119 ret = atomic_dec_if_positive(&sem->count) < 0;
124 extern inline void up(struct semaphore * sem)
126 #ifdef WAITQUEUE_DEBUG
127 CHECK_MAGIC(sem->__magic);
131 if (atomic_inc_return(&sem->count) <= 0)
135 #endif /* __KERNEL__ */
137 #endif /* !(_PPC_SEMAPHORE_H) */