LXR linux-old/include/asm-ppc64/semaphore.h

   1#ifndef _PPC64_SEMAPHORE_H
   2#define _PPC64_SEMAPHORE_H
   3
   4/*
   5 * Remove spinlock-based RW semaphores; RW semaphore definitions are
   6 * now in rwsem.h and we use the generic lib/rwsem.c implementation.
   7 * Rework semaphores to use atomic_dec_if_positive.
   8 * -- Paul Mackerras (paulus@samba.org)
   9 */
  10
  11#ifdef __KERNEL__
  12
  13#include <asm/atomic.h>
  14#include <asm/system.h>
  15#include <linux/wait.h>
  16#include <linux/rwsem.h>
  17
  18struct semaphore {
  19        /*
  20         * Note that any negative value of count is equivalent to 0,
  21         * but additionally indicates that some process(es) might be
  22         * sleeping on `wait'.
  23         */
  24        atomic_t count;
  25        wait_queue_head_t wait;
  26#if WAITQUEUE_DEBUG
  27        long __magic;
  28#endif
  29};
  30
  31#if WAITQUEUE_DEBUG
  32# define __SEM_DEBUG_INIT(name) \
  33                , (long)&(name).__magic
  34#else
  35# define __SEM_DEBUG_INIT(name)
  36#endif
  37
  38#define __SEMAPHORE_INITIALIZER(name, count) \
  39        { ATOMIC_INIT(count), \
  40          __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
  41          __SEM_DEBUG_INIT(name) }
  42
  43#define __MUTEX_INITIALIZER(name) \
  44        __SEMAPHORE_INITIALIZER(name, 1)
  45
  46#define __DECLARE_SEMAPHORE_GENERIC(name, count) \
  47        struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  48
  49#define DECLARE_MUTEX(name)             __DECLARE_SEMAPHORE_GENERIC(name, 1)
  50#define DECLARE_MUTEX_LOCKED(name)      __DECLARE_SEMAPHORE_GENERIC(name, 0)
  51
  52static inline void sema_init (struct semaphore *sem, int val)
  53{
  54        atomic_set(&sem->count, val);
  55        init_waitqueue_head(&sem->wait);
  56#if WAITQUEUE_DEBUG
  57        sem->__magic = (long)&sem->__magic;
  58#endif
  59}
  60
  61static inline void init_MUTEX (struct semaphore *sem)
  62{
  63        sema_init(sem, 1);
  64}
  65
  66static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  67{
  68        sema_init(sem, 0);
  69}
  70
  71extern void __down(struct semaphore * sem);
  72extern int  __down_interruptible(struct semaphore * sem);
  73extern void __up(struct semaphore * sem);
  74
  75static inline void down(struct semaphore * sem)
  76{
  77#if WAITQUEUE_DEBUG
  78        CHECK_MAGIC(sem->__magic);
  79#endif
  80
  81        /*
  82         * Try to get the semaphore, take the slow path if we fail.
  83         */
  84        if (atomic_dec_return(&sem->count) < 0)
  85                __down(sem);
  86        smp_wmb();
  87}
  88
  89static inline int down_interruptible(struct semaphore * sem)
  90{
  91        int ret = 0;
  92
  93#if WAITQUEUE_DEBUG
  94        CHECK_MAGIC(sem->__magic);
  95#endif
  96
  97        if (atomic_dec_return(&sem->count) < 0)
  98                ret = __down_interruptible(sem);
  99        smp_wmb();
 100        return ret;
 101}
 102
 103static inline int down_trylock(struct semaphore * sem)
 104{
 105        int ret;
 106
 107#if WAITQUEUE_DEBUG
 108        CHECK_MAGIC(sem->__magic);
 109#endif
 110
 111        ret = atomic_dec_if_positive(&sem->count) < 0;
 112        smp_wmb();
 113        return ret;
 114}
 115
 116static inline void up(struct semaphore * sem)
 117{
 118#if WAITQUEUE_DEBUG
 119        CHECK_MAGIC(sem->__magic);
 120#endif
 121
 122        smp_wmb();
 123        if (atomic_inc_return(&sem->count) <= 0)
 124                __up(sem);
 125}
 126
 127static inline int sem_getcount(struct semaphore *sem)
 128{
 129        return atomic_read(&sem->count);
 130}
 131
 132#endif /* __KERNEL__ */
 133
 134#endif /* !(_PPC64_SEMAPHORE_H) */
 135