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  1. #ifndef __LINUX_SPINLOCK_UP_H
  2. #define __LINUX_SPINLOCK_UP_H
  3.  
  4. #ifndef __LINUX_SPINLOCK_H
  5. # error "please don't include this file directly"
  6. #endif
  7.  
  8. #include <asm/processor.h>      /* for cpu_relax() */
  9.  
  10. /*
  11.  * include/linux/spinlock_up.h - UP-debug version of spinlocks.
  12.  *
  13.  * portions Copyright 2005, Red Hat, Inc., Ingo Molnar
  14.  * Released under the General Public License (GPL).
  15.  *
  16.  * In the debug case, 1 means unlocked, 0 means locked. (the values
  17.  * are inverted, to catch initialization bugs)
  18.  *
  19.  * No atomicity anywhere, we are on UP. However, we still need
  20.  * the compiler barriers, because we do not want the compiler to
  21.  * move potentially faulting instructions (notably user accesses)
  22.  * into the locked sequence, resulting in non-atomic execution.
  23.  */
  24.  
  25. #ifdef CONFIG_DEBUG_SPINLOCK
  26. #define arch_spin_is_locked(x)          ((x)->slock == 0)
  27.  
  28. static inline void arch_spin_lock(arch_spinlock_t *lock)
  29. {
  30.         lock->slock = 0;
  31.         barrier();
  32. }
  33.  
  34. static inline void
  35. arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
  36. {
  37.         local_irq_save(flags);
  38.         lock->slock = 0;
  39.         barrier();
  40. }
  41.  
  42. static inline int arch_spin_trylock(arch_spinlock_t *lock)
  43. {
  44.         char oldval = lock->slock;
  45.  
  46.         lock->slock = 0;
  47.         barrier();
  48.  
  49.         return oldval > 0;
  50. }
  51.  
  52. static inline void arch_spin_unlock(arch_spinlock_t *lock)
  53. {
  54.         barrier();
  55.         lock->slock = 1;
  56. }
  57.  
  58. /*
  59.  * Read-write spinlocks. No debug version.
  60.  */
  61. #define arch_read_lock(lock)            do { barrier(); (void)(lock); } while (0)
  62. #define arch_write_lock(lock)           do { barrier(); (void)(lock); } while (0)
  63. #define arch_read_trylock(lock) ({ barrier(); (void)(lock); 1; })
  64. #define arch_write_trylock(lock)        ({ barrier(); (void)(lock); 1; })
  65. #define arch_read_unlock(lock)          do { barrier(); (void)(lock); } while (0)
  66. #define arch_write_unlock(lock) do { barrier(); (void)(lock); } while (0)
  67.  
  68. #else /* DEBUG_SPINLOCK */
  69. #define arch_spin_is_locked(lock)       ((void)(lock), 0)
  70. /* for sched/core.c and kernel_lock.c: */
  71. # define arch_spin_lock(lock)           do { barrier(); (void)(lock); } while (0)
  72. # define arch_spin_lock_flags(lock, flags)      do { barrier(); (void)(lock); } while (0)
  73. # define arch_spin_unlock(lock) do { barrier(); (void)(lock); } while (0)
  74. # define arch_spin_trylock(lock)        ({ barrier(); (void)(lock); 1; })
  75. #endif /* DEBUG_SPINLOCK */
  76.  
  77. #define arch_spin_is_contended(lock)    (((void)(lock), 0))
  78.  
  79. #define arch_read_can_lock(lock)        (((void)(lock), 1))
  80. #define arch_write_can_lock(lock)       (((void)(lock), 1))
  81.  
  82. #define arch_spin_unlock_wait(lock) \
  83.                 do { cpu_relax(); } while (arch_spin_is_locked(lock))
  84.  
  85. #endif /* __LINUX_SPINLOCK_UP_H */
  86.