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semaphore-helper.h
Package: linux-2.4.20.tar.gz　[view]
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Upload Date: 2013-04-10
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Linux-Unix program

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Unix_Linux

semaphore-helper.h：Code Content
  1. #ifndef _M68K_SEMAPHORE_HELPER_H
  2. #define _M68K_SEMAPHORE_HELPER_H
  4. /*
  5.  * SMP- and interrupt-safe semaphores helper functions.
  6.  *
  7.  * (C) Copyright 1996 Linus Torvalds
  8.  *
  9.  * m68k version by Andreas Schwab
  10.  */
  12. #include <linux/config.h>
  14. /*
  15.  * These two _must_ execute atomically wrt each other.
  16.  */
  17. static inline void wake_one_more(struct semaphore * sem)
  18. {
  19. atomic_inc(&sem->waking);
  20. }
  22. #ifndef CONFIG_RMW_INSNS
  23. extern spinlock_t semaphore_wake_lock;
  24. #endif
  26. static inline int waking_non_zero(struct semaphore *sem)
  27. {
  28. int ret;
  29. #ifndef CONFIG_RMW_INSNS
  30. unsigned long flags;
  32. spin_lock_irqsave(&semaphore_wake_lock, flags);
  33. ret = 0;
  34. if (atomic_read(&sem->waking) > 0) {
  35. atomic_dec(&sem->waking);
  36. ret = 1;
  37. }
  38. spin_unlock_irqrestore(&semaphore_wake_lock, flags);
  39. #else
  40. int tmp1, tmp2;
  42. __asm__ __volatile__
  43.   ("1: movel %1,%2n"
  44.    "    jle 2fn"
  45.    " subql #1,%2n"
  46.    " casl %1,%2,%3n"
  47.    " jne 1bn"
  48.    " moveq #1,%0n"
  49.    "2:"
  50.    : "=d" (ret), "=d" (tmp1), "=d" (tmp2)
  51.    : "m" (sem->waking), "0" (0), "1" (sem->waking));
  52. #endif
  54. return ret;
  55. }
  57. /*
  58.  * waking_non_zero_interruptible:
  59.  * 1 got the lock
  60.  * 0 go to sleep
  61.  * -EINTR interrupted
  62.  */
  63. static inline int waking_non_zero_interruptible(struct semaphore *sem,
  64. struct task_struct *tsk)
  65. {
  66. int ret;
  67. #ifndef CONFIG_RMW_INSNS
  68. unsigned long flags;
  70. spin_lock_irqsave(&semaphore_wake_lock, flags);
  71. ret = 0;
  72. if (atomic_read(&sem->waking) > 0) {
  73. atomic_dec(&sem->waking);
  74. ret = 1;
  75. } else if (signal_pending(tsk)) {
  76. atomic_inc(&sem->count);
  77. ret = -EINTR;
  78. }
  79. spin_unlock_irqrestore(&semaphore_wake_lock, flags);
  80. #else
  81. int tmp1, tmp2;
  83. __asm__ __volatile__
  84.   ("1: movel %1,%2n"
  85.    " jle 2fn"
  86.    " subql #1,%2n"
  87.    " casl %1,%2,%3n"
  88.    " jne 1bn"
  89.    " moveq #1,%0n"
  90.    " jra %a4n"
  91.    "2:"
  92.    : "=d" (ret), "=d" (tmp1), "=d" (tmp2)
  93.    : "m" (sem->waking), "i" (&&next), "0" (0), "1" (sem->waking));
  94. if (signal_pending(tsk)) {
  95. atomic_inc(&sem->count);
  96. ret = -EINTR;
  97. }
  98. next:
  99. #endif
  101. return ret;
  102. }
  104. /*
  105.  * waking_non_zero_trylock:
  106.  * 1 failed to lock
  107.  * 0 got the lock
  108.  */
  109. static inline int waking_non_zero_trylock(struct semaphore *sem)
  110. {
  111. int ret;
  112. #ifndef CONFIG_RMW_INSNS
  113. unsigned long flags;
  115. spin_lock_irqsave(&semaphore_wake_lock, flags);
  116. ret = 1;
  117. if (atomic_read(&sem->waking) > 0) {
  118. atomic_dec(&sem->waking);
  119. ret = 0;
  120. } else
  121. atomic_inc(&sem->count);
  122. spin_unlock_irqrestore(&semaphore_wake_lock, flags);
  123. #else
  124. int tmp1, tmp2;
  126. __asm__ __volatile__
  127.   ("1: movel %1,%2n"
  128.    "    jle 2fn"
  129.    " subql #1,%2n"
  130.    " casl %1,%2,%3n"
  131.    " jne 1bn"
  132.    " moveq #0,%0n"
  133.    "2:"
  134.    : "=d" (ret), "=d" (tmp1), "=d" (tmp2)
  135.    : "m" (sem->waking), "0" (1), "1" (sem->waking));
  136. if (ret)
  137. atomic_inc(&sem->count);
  138. #endif
  139. return ret;
  140. }
  142. #endif