include/asm-ia64/semaphore.h

   1 #ifndef _ASM_IA64_SEMAPHORE_H
   2 #define _ASM_IA64_SEMAPHORE_H
   3
   4 /*
   5  * Copyright (C) 1998-2000 Hewlett-Packard Co
   6  * Copyright (C) 1998-2000 David Mosberger-Tang <davidm@hpl.hp.com>
   7  */
   8
   9 #include <linux/wait.h>
  10 #include <linux/rwsem.h>
  11
  12 #include <asm/atomic.h>
  13
  14 struct semaphore {
  15         atomic_t count;
  16         int sleepers;
  17         wait_queue_head_t wait;
  18 };
  19
  20 #define __SEMAPHORE_INITIALIZER(name, n)                                \
  21 {                                                                       \
  22         .count          = ATOMIC_INIT(n),                               \
  23         .sleepers       = 0,                                            \
  24         .wait           = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)    \
  25 }
  26
  27 #define __MUTEX_INITIALIZER(name)       __SEMAPHORE_INITIALIZER(name,1)
  28
  29 #define __DECLARE_SEMAPHORE_GENERIC(name,count)                                 \
  30         struct semaphore name = __SEMAPHORE_INITIALIZER(name, count)
  31
  32 #define DECLARE_MUTEX(name)             __DECLARE_SEMAPHORE_GENERIC(name, 1)
  33 #define DECLARE_MUTEX_LOCKED(name)      __DECLARE_SEMAPHORE_GENERIC(name, 0)
  34
  35 static inline void
  36 sema_init (struct semaphore *sem, int val)
  37 {
  38         *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
  39 }
  40
  41 static inline void
  42 init_MUTEX (struct semaphore *sem)
  43 {
  44         sema_init(sem, 1);
  45 }
  46
  47 static inline void
  48 init_MUTEX_LOCKED (struct semaphore *sem)
  49 {
  50         sema_init(sem, 0);
  51 }
  52
  53 extern void __down (struct semaphore * sem);
  54 extern int  __down_interruptible (struct semaphore * sem);
  55 extern int  __down_trylock (struct semaphore * sem);
  56 extern void __up (struct semaphore * sem);
  57
  58 /*
  59  * Atomically decrement the semaphore's count.  If it goes negative,
  60  * block the calling thread in the TASK_UNINTERRUPTIBLE state.
  61  */
  62 static inline void
  63 down (struct semaphore *sem)
  64 {
  65         might_sleep();
  66         if (atomic_dec_return(&sem->count) < 0)
  67                 __down(sem);
  68 }
  69
  70 /*
  71  * Atomically decrement the semaphore's count.  If it goes negative,
  72  * block the calling thread in the TASK_INTERRUPTIBLE state.
  73  */
  74 static inline int
  75 down_interruptible (struct semaphore * sem)
  76 {
  77         int ret = 0;
  78
  79         might_sleep();
  80         if (atomic_dec_return(&sem->count) < 0)
  81                 ret = __down_interruptible(sem);
  82         return ret;
  83 }
  84
  85 static inline int
  86 down_trylock (struct semaphore *sem)
  87 {
  88         int ret = 0;
  89
  90         if (atomic_dec_return(&sem->count) < 0)
  91                 ret = __down_trylock(sem);
  92         return ret;
  93 }
  94
  95 static inline void
  96 up (struct semaphore * sem)
  97 {
  98         if (atomic_inc_return(&sem->count) <= 0)
  99                 __up(sem);
 100 }
 101
 102 #endif /* _ASM_IA64_SEMAPHORE_H */