LXR linux/include/linux/spinlock

   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/*
   9 * include/linux/spinlock_up.h - UP-debug version of spinlocks.
  10 *
  11 * portions Copyright 2005, Red Hat, Inc., Ingo Molnar
  12 * Released under the General Public License (GPL).
  13 *
  14 * In the debug case, 1 means unlocked, 0 means locked. (the values
  15 * are inverted, to catch initialization bugs)
  16 *
  17 * No atomicity anywhere, we are on UP.
  18 */
  19
  20#ifdef CONFIG_DEBUG_SPINLOCK
  21#define __raw_spin_is_locked(x)         ((x)->slock == 0)
  22
  23static inline void __raw_spin_lock(raw_spinlock_t *lock)
  24{
  25        lock->slock = 0;
  26}
  27
  28static inline void
  29__raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
  30{
  31        local_irq_save(flags);
  32        lock->slock = 0;
  33}
  34
  35static inline int __raw_spin_trylock(raw_spinlock_t *lock)
  36{
  37        char oldval = lock->slock;
  38
  39        lock->slock = 0;
  40
  41        return oldval > 0;
  42}
  43
  44static inline void __raw_spin_unlock(raw_spinlock_t *lock)
  45{
  46        lock->slock = 1;
  47}
  48
  49/*
  50 * Read-write spinlocks. No debug version.
  51 */
  52#define __raw_read_lock(lock)           do { (void)(lock); } while (0)
  53#define __raw_write_lock(lock)          do { (void)(lock); } while (0)
  54#define __raw_read_trylock(lock)        ({ (void)(lock); 1; })
  55#define __raw_write_trylock(lock)       ({ (void)(lock); 1; })
  56#define __raw_read_unlock(lock)         do { (void)(lock); } while (0)
  57#define __raw_write_unlock(lock)        do { (void)(lock); } while (0)
  58
  59#else /* DEBUG_SPINLOCK */
  60#define __raw_spin_is_locked(lock)      ((void)(lock), 0)
  61/* for sched.c and kernel_lock.c: */
  62# define __raw_spin_lock(lock)          do { (void)(lock); } while (0)
  63# define __raw_spin_lock_flags(lock, flags)     do { (void)(lock); } while (0)
  64# define __raw_spin_unlock(lock)        do { (void)(lock); } while (0)
  65# define __raw_spin_trylock(lock)       ({ (void)(lock); 1; })
  66#endif /* DEBUG_SPINLOCK */
  67
  68#define __raw_spin_is_contended(lock)   (((void)(lock), 0))
  69
  70#define __raw_read_can_lock(lock)       (((void)(lock), 1))
  71#define __raw_write_can_lock(lock)      (((void)(lock), 1))
  72
  73#define __raw_spin_unlock_wait(lock) \
  74                do { cpu_relax(); } while (__raw_spin_is_locked(lock))
  75
  76#endif /* __LINUX_SPINLOCK_UP_H */
  77