static inline void __lock_kernel(void)
{
preempt_disable();
if (unlikely(!_raw_spin_trylock(&kernel_flag))) {
/*
* If preemption was disabled even before this
* was called, there's nothing we can be polite
* about - just spin.
*/
if (preempt_count() > 1) {
_raw_spin_lock(&kernel_flag);
return;
}
/*
* Otherwise, let's wait for the kernel lock
* with preemption enabled..
*/
do {
preempt_enable();
while (spin_is_locked(&kernel_flag))
cpu_relax();
preempt_disable();
} while (!_raw_spin_trylock(&kernel_flag));
}
}
void _spin_lock(spinlock_t *lock)
{
check_lock(&lock->debug);
while ( unlikely(!_raw_spin_trylock(&lock->raw)) )
while ( likely(_raw_spin_is_locked(&lock->raw)) )
cpu_relax();
}
int __lockfunc _spin_trylock(spinlock_t *lock)
{
preempt_disable();
if (_raw_spin_trylock(lock))
return 1;
preempt_enable();
return 0;
}
/*
* Acquire/release the underlying lock from the scheduler.
*
* This is called with preemption disabled, and should
* return an error value if it cannot get the lock and
* TIF_NEED_RESCHED gets set.
*
* If it successfully gets the lock, it should increment
* the preemption count like any spinlock does.
*
* (This works on UP too - _raw_spin_trylock will never
* return false in that case)
*/
int __lockfunc __reacquire_kernel_lock(void)
{
while (!_raw_spin_trylock(&kernel_flag)) {
if (need_resched())
return -EAGAIN;
cpu_relax();
}
preempt_disable();
return 0;
}
/*
* Acquire/release the underlying lock from the scheduler.
*
* This is called with preemption disabled, and should
* return an error value if it cannot get the lock and
* TIF_NEED_RESCHED gets set.
*
* If it successfully gets the lock, it should increment
* the preemption count like any spinlock does.
*
* (This works on UP too - _raw_spin_trylock will never
* return false in that case)
*/
int __lockfunc __reacquire_kernel_lock(void)
{
while (!_raw_spin_trylock(&kernel_flag)) {
if (test_thread_flag(TIF_NEED_RESCHED))
return -EAGAIN;
cpu_relax();
}
preempt_disable();
return 0;
}
int __lockfunc _spin_trylock(spinlock_t *lock)
{
preempt_disable();
if (_raw_spin_trylock(lock)) {
spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
return 1;
}
preempt_enable();
return 0;
}
int __lockfunc _spin_trylock_bh(spinlock_t *lock)
{
local_bh_disable();
preempt_disable();
if (_raw_spin_trylock(lock))
return 1;
preempt_enable_no_resched();
local_bh_enable();
return 0;
}
int __lockfunc _spin_trylock_bh(spinlock_t *lock)
{
local_bh_disable();
preempt_disable();
if (_raw_spin_trylock(lock)) {
spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
return 1;
}
preempt_enable_no_resched();
local_bh_enable_ip((unsigned long)__builtin_return_address(0));
return 0;
}
void _spin_lock_irq(spinlock_t *lock)
{
ASSERT(local_irq_is_enabled());
local_irq_disable();
check_lock(&lock->debug);
while ( unlikely(!_raw_spin_trylock(&lock->raw)) )
{
local_irq_enable();
while ( likely(_raw_spin_is_locked(&lock->raw)) )
cpu_relax();
local_irq_disable();
}
}
unsigned long _spin_lock_irqsave(spinlock_t *lock)
{
unsigned long flags;
local_irq_save(flags);
check_lock(&lock->debug);
while ( unlikely(!_raw_spin_trylock(&lock->raw)) )
{
local_irq_restore(flags);
while ( likely(_raw_spin_is_locked(&lock->raw)) )
cpu_relax();
local_irq_save(flags);
}
return flags;
}
/*
* This could be a long-held lock. If another CPU holds it for a long time,
* and that CPU is not asked to reschedule then *this* CPU will spin on the
* lock for a long time, even if *this* CPU is asked to reschedule.
*
* So what we do here, in the slow (contended) path is to spin on the lock by
* hand while permitting preemption.
*
* Called inside preempt_disable().
*/
static inline void __preempt_spin_lock(spinlock_t *lock)
{
if (preempt_count() > 1) {
_raw_spin_lock(lock);
return;
}
do {
preempt_enable();
while (spin_is_locked(lock))
cpu_relax();
preempt_disable();
} while (!_raw_spin_trylock(lock));
}
int _spin_trylock(spinlock_t *lock)
{
check_lock(&lock->debug);
return _raw_spin_trylock(&lock->raw);
}
void __lockfunc _spin_lock(spinlock_t *lock)
{
preempt_disable();
if (unlikely(!_raw_spin_trylock(lock)))
__preempt_spin_lock(lock);
}
