linux/include/linux/spinlock_up.h
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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.
  20 */
  21
  22#ifdef CONFIG_DEBUG_SPINLOCK
  23#define arch_spin_is_locked(x)          ((x)->slock == 0)
  24
  25static inline void arch_spin_lock(arch_spinlock_t *lock)
  26{
  27        lock->slock = 0;
  28}
  29
  30static inline void
  31arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
  32{
  33        local_irq_save(flags);
  34        lock->slock = 0;
  35}
  36
  37static inline int arch_spin_trylock(arch_spinlock_t *lock)
  38{
  39        char oldval = lock->slock;
  40
  41        lock->slock = 0;
  42
  43        return oldval > 0;
  44}
  45
  46static inline void arch_spin_unlock(arch_spinlock_t *lock)
  47{
  48        lock->slock = 1;
  49}
  50
  51/*
  52 * Read-write spinlocks. No debug version.
  53 */
  54#define arch_read_lock(lock)            do { (void)(lock); } while (0)
  55#define arch_write_lock(lock)           do { (void)(lock); } while (0)
  56#define arch_read_trylock(lock) ({ (void)(lock); 1; })
  57#define arch_write_trylock(lock)        ({ (void)(lock); 1; })
  58#define arch_read_unlock(lock)          do { (void)(lock); } while (0)
  59#define arch_write_unlock(lock) do { (void)(lock); } while (0)
  60
  61#else /* DEBUG_SPINLOCK */
  62#define arch_spin_is_locked(lock)       ((void)(lock), 0)
  63/* for sched.c and kernel_lock.c: */
  64# define arch_spin_lock(lock)           do { (void)(lock); } while (0)
  65# define arch_spin_lock_flags(lock, flags)      do { (void)(lock); } while (0)
  66# define arch_spin_unlock(lock) do { (void)(lock); } while (0)
  67# define arch_spin_trylock(lock)        ({ (void)(lock); 1; })
  68#endif /* DEBUG_SPINLOCK */
  69
  70#define arch_spin_is_contended(lock)    (((void)(lock), 0))
  71
  72#define arch_read_can_lock(lock)        (((void)(lock), 1))
  73#define arch_write_can_lock(lock)       (((void)(lock), 1))
  74
  75#define arch_spin_unlock_wait(lock) \
  76                do { cpu_relax(); } while (arch_spin_is_locked(lock))
  77
  78#endif /* __LINUX_SPINLOCK_UP_H */
  79
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