#ifndef __LINUX_SPINLOCK_UP_H
  #define __LINUX_SPINLOCK_UP_H
  
  #ifndef __LINUX_SPINLOCK_H
  # error "please don't include this file directly"
  #endif
  
  #include <asm/processor.h>	/* for cpu_relax() */
  #include <asm/barrier.h>
  
  /*
   * include/linux/spinlock_up.h - UP-debug version of spinlocks.
   *
   * portions Copyright 2005, Red Hat, Inc., Ingo Molnar
   * Released under the General Public License (GPL).
   *
   * In the debug case, 1 means unlocked, 0 means locked. (the values
   * are inverted, to catch initialization bugs)
   *
   * No atomicity anywhere, we are on UP. However, we still need
   * the compiler barriers, because we do not want the compiler to
   * move potentially faulting instructions (notably user accesses)
   * into the locked sequence, resulting in non-atomic execution.
   */
  
  #ifdef CONFIG_DEBUG_SPINLOCK
  #define arch_spin_is_locked(x)		((x)->slock == 0)
  
  static inline void arch_spin_lock(arch_spinlock_t *lock)
  {
  	lock->slock = 0;
  	barrier();
  }
  
  static inline int arch_spin_trylock(arch_spinlock_t *lock)
  {
  	char oldval = lock->slock;
  
  	lock->slock = 0;
  	barrier();
  
  	return oldval > 0;
  }
  
  static inline void arch_spin_unlock(arch_spinlock_t *lock)
  {
  	barrier();
  	lock->slock = 1;
  }
  
  /*
   * Read-write spinlocks. No debug version.
   */
  #define arch_read_lock(lock)		do { barrier(); (void)(lock); } while (0)
  #define arch_write_lock(lock)		do { barrier(); (void)(lock); } while (0)
  #define arch_read_trylock(lock)	({ barrier(); (void)(lock); 1; })
  #define arch_write_trylock(lock)	({ barrier(); (void)(lock); 1; })
  #define arch_read_unlock(lock)		do { barrier(); (void)(lock); } while (0)
  #define arch_write_unlock(lock)	do { barrier(); (void)(lock); } while (0)
  
  #else /* DEBUG_SPINLOCK */
  #define arch_spin_is_locked(lock)	((void)(lock), 0)
  /* for sched/core.c and kernel_lock.c: */
  # define arch_spin_lock(lock)		do { barrier(); (void)(lock); } while (0)
  # define arch_spin_lock_flags(lock, flags)	do { barrier(); (void)(lock); } while (0)
  # define arch_spin_unlock(lock)	do { barrier(); (void)(lock); } while (0)
  # define arch_spin_trylock(lock)	({ barrier(); (void)(lock); 1; })
  #endif /* DEBUG_SPINLOCK */
  
  #define arch_spin_is_contended(lock)	(((void)(lock), 0))
  
  #endif /* __LINUX_SPINLOCK_UP_H */