root/include/linux/spinlock_up.h

INCLUDED FROM

DEFINITIONS

1. __raw_spin_lock
2. __raw_spin_lock_flags
3. __raw_spin_trylock
4. __raw_spin_unlock

#ifndef __LINUX_SPINLOCK_UP_H
#define __LINUX_SPINLOCK_UP_H

#ifndef __LINUX_SPINLOCK_H
# error "please don't include this file directly"
#endif

/*
 * 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.
 */

#ifdef CONFIG_DEBUG_SPINLOCK
#define __raw_spin_is_locked(x)         ((x)->slock == 0)

static inline void __raw_spin_lock(raw_spinlock_t *lock)
{
        lock->slock = 0;
}

static inline void
__raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
{
        local_irq_save(flags);
        lock->slock = 0;
}

static inline int __raw_spin_trylock(raw_spinlock_t *lock)
{
        char oldval = lock->slock;

        lock->slock = 0;

        return oldval > 0;
}

static inline void __raw_spin_unlock(raw_spinlock_t *lock)
{
        lock->slock = 1;
}

/*
 * Read-write spinlocks. No debug version.
 */
#define __raw_read_lock(lock)           do { (void)(lock); } while (0)
#define __raw_write_lock(lock)          do { (void)(lock); } while (0)
#define __raw_read_trylock(lock)        ({ (void)(lock); 1; })
#define __raw_write_trylock(lock)       ({ (void)(lock); 1; })
#define __raw_read_unlock(lock)         do { (void)(lock); } while (0)
#define __raw_write_unlock(lock)        do { (void)(lock); } while (0)

#else /* DEBUG_SPINLOCK */
#define __raw_spin_is_locked(lock)      ((void)(lock), 0)
/* for sched.c and kernel_lock.c: */
# define __raw_spin_lock(lock)          do { (void)(lock); } while (0)
# define __raw_spin_unlock(lock)        do { (void)(lock); } while (0)
# define __raw_spin_trylock(lock)       ({ (void)(lock); 1; })
#endif /* DEBUG_SPINLOCK */

#define __raw_spin_is_contended(lock)   (((void)(lock), 0))

#define __raw_read_can_lock(lock)       (((void)(lock), 1))
#define __raw_write_can_lock(lock)      (((void)(lock), 1))

#define __raw_spin_unlock_wait(lock) \
                do { cpu_relax(); } while (__raw_spin_is_locked(lock))

#endif /* __LINUX_SPINLOCK_UP_H */