LXR linux-old/include/asm-ppc/semaphore.h

   1#ifndef _PPC_SEMAPHORE_H
   2#define _PPC_SEMAPHORE_H
   3
   4/*
   5 * Swiped from asm-sparc/semaphore.h and modified
   6 * -- Cort (cort@cs.nmt.edu)
   7 *
   8 * Stole some rw spinlock-based semaphore stuff from asm-alpha/semaphore.h
   9 * -- Ani Joshi (ajoshi@unixbox.com)
  10 *
  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)
  15 */
  16
  17#ifdef __KERNEL__
  18
  19#include <asm/atomic.h>
  20#include <asm/system.h>
  21#include <linux/wait.h>
  22#include <linux/rwsem.h>
  23
  24struct semaphore {
  25        /*
  26         * Note that any negative value of count is equivalent to 0,
  27         * but additionally indicates that some process(es) might be
  28         * sleeping on `wait'.
  29         */
  30        atomic_t count;
  31        wait_queue_head_t wait;
  32#if WAITQUEUE_DEBUG
  33        long __magic;
  34#endif
  35};
  36
  37#if WAITQUEUE_DEBUG
  38# define __SEM_DEBUG_INIT(name) \
  39                , (long)&(name).__magic
  40#else
  41# define __SEM_DEBUG_INIT(name)
  42#endif
  43
  44#define __SEMAPHORE_INITIALIZER(name, count) \
  45        { ATOMIC_INIT(count), \
  46          __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
  47          __SEM_DEBUG_INIT(name) }
  48
  49#define __MUTEX_INITIALIZER(name) \
  50        __SEMAPHORE_INITIALIZER(name, 1)
  51
  52#define __DECLARE_SEMAPHORE_GENERIC(name, count) \
  53        struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  54
  55#define DECLARE_MUTEX(name)             __DECLARE_SEMAPHORE_GENERIC(name, 1)
  56#define DECLARE_MUTEX_LOCKED(name)      __DECLARE_SEMAPHORE_GENERIC(name, 0)
  57
  58static inline void sema_init (struct semaphore *sem, int val)
  59{
  60        atomic_set(&sem->count, val);
  61        init_waitqueue_head(&sem->wait);
  62#if WAITQUEUE_DEBUG
  63        sem->__magic = (long)&sem->__magic;
  64#endif
  65}
  66
  67static inline void init_MUTEX (struct semaphore *sem)
  68{
  69        sema_init(sem, 1);
  70}
  71
  72static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  73{
  74        sema_init(sem, 0);
  75}
  76
  77extern void __down(struct semaphore * sem);
  78extern int  __down_interruptible(struct semaphore * sem);
  79extern void __up(struct semaphore * sem);
  80
  81extern inline void down(struct semaphore * sem)
  82{
  83#if WAITQUEUE_DEBUG
  84        CHECK_MAGIC(sem->__magic);
  85#endif
  86
  87        /*
  88         * Try to get the semaphore, take the slow path if we fail.
  89         */
  90        if (atomic_dec_return(&sem->count) < 0)
  91                __down(sem);
  92        smp_wmb();
  93}
  94
  95extern inline int down_interruptible(struct semaphore * sem)
  96{
  97        int ret = 0;
  98
  99#if WAITQUEUE_DEBUG
 100        CHECK_MAGIC(sem->__magic);
 101#endif
 102
 103        if (atomic_dec_return(&sem->count) < 0)
 104                ret = __down_interruptible(sem);
 105        smp_wmb();
 106        return ret;
 107}
 108
 109extern inline int down_trylock(struct semaphore * sem)
 110{
 111        int ret;
 112
 113#if WAITQUEUE_DEBUG
 114        CHECK_MAGIC(sem->__magic);
 115#endif
 116
 117        ret = atomic_dec_if_positive(&sem->count) < 0;
 118        smp_wmb();
 119        return ret;
 120}
 121
 122extern inline void up(struct semaphore * sem)
 123{
 124#if WAITQUEUE_DEBUG
 125        CHECK_MAGIC(sem->__magic);
 126#endif
 127
 128        smp_wmb();
 129        if (atomic_inc_return(&sem->count) <= 0)
 130                __up(sem);
 131}
 132
 133static inline int sem_getcount(struct semaphore *sem)
 134{
 135        return atomic_read(&sem->count);
 136}
 137
 138#endif /* __KERNEL__ */
 139
 140#endif /* !(_PPC_SEMAPHORE_H) */
 141