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#ifndef __LINUX_BIT_SPINLOCK_H
#define __LINUX_BIT_SPINLOCK_H
/*
* bit-based spin_lock()
*
* Don't use this unless you really need to: spin_lock() and spin_unlock()
* are significantly faster.
*/
static inline void bit_spin_lock(int bitnum, unsigned long *addr)
{
/*
* Assuming the lock is uncontended, this never enters
* the body of the outer loop. If it is contended, then
* within the inner loop a non-atomic test is used to
* busywait with less bus contention for a good time to
* attempt to acquire the lock bit.
*/
preempt_disable();
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
while (test_and_set_bit(bitnum, addr)) {
while (test_bit(bitnum, addr)) {
preempt_enable();
cpu_relax();
preempt_disable();
}
}
#endif
__acquire(bitlock);
}
/*
* Return true if it was acquired
*/
static inline int bit_spin_trylock(int bitnum, unsigned long *addr)
{
preempt_disable();
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
if (test_and_set_bit(bitnum, addr)) {
preempt_enable();
return 0;
}
#endif
__acquire(bitlock);
return 1;
}
/*
* bit-based spin_unlock()
*/
static inline void bit_spin_unlock(int bitnum, unsigned long *addr)
{
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
BUG_ON(!test_bit(bitnum, addr));
smp_mb__before_clear_bit();
clear_bit(bitnum, addr);
#endif
preempt_enable();
__release(bitlock);
}
/*
* Return true if the lock is held.
*/
static inline int bit_spin_is_locked(int bitnum, unsigned long *addr)
{
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
return test_bit(bitnum, addr);
#elif defined CONFIG_PREEMPT
return preempt_count();
#else
return 1;
#endif
}
#endif /* __LINUX_BIT_SPINLOCK_H */
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