void __lockfunc _spin_lock_irq(spinlock_t *lock)
{
local_irq_disable();
preempt_disable();
spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
}
int __lockfunc rt_spin_trylock(spinlock_t *lock)
{
int ret = rt_mutex_trylock(&lock->lock);
if (ret)
spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
return ret;
}
int __lockfunc rt_spin_trylock_irqsave(spinlock_t *lock, unsigned long *flags)
{
int ret;
*flags = 0;
ret = rt_mutex_trylock(&lock->lock);
if (ret)
spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
return ret;
}
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;
}
//在单CPU的系统中，进入临界区代码只需要关闭中断就可以了，
//而多CPU的系统中，还需要测试自旋锁的状态
void __lockfunc _spin_lock_irq(spinlock_t *lock)
{
local_irq_disable();//关闭中断
//关闭进程抢占，由于中观或系统调用之后，可能会调度其他进程运行
//(例如当前进程时间片用完，或者有一个拥有更高优先级的进程已经进入了就绪状态)，
//preempt_disable()关闭调度器的这个功能，从而保证当前进程在执行临界区代码的过程中不会被其他进程干扰
preempt_disable();
spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
//其实就是调用_raw_spin_lock()函数。#define LOCK_CONTENDED(_lock, try, lock) lock(_lock)
LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
}
unsigned long __lockfunc _raw_spin_lock_irqsave_nested(raw_spinlock_t *lock,
int subclass)
{
unsigned long flags;
local_irq_save(flags);
preempt_disable();
spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
LOCK_CONTENDED_FLAGS(lock, do_raw_spin_trylock, do_raw_spin_lock,
do_raw_spin_lock_flags, &flags);
return flags;
}
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;
}
unsigned long __lockfunc _spin_lock_irqsave(spinlock_t *lock)
{
unsigned long flags;
local_irq_save(flags);
preempt_disable();
spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
/*
* On lockdep we dont want the hand-coded irq-enable of
* _raw_spin_lock_flags() code, because lockdep assumes
* that interrupts are not re-enabled during lock-acquire:
*/
#ifdef CONFIG_LOCKDEP
LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
#else
_raw_spin_lock_flags(lock, &flags);
#endif
return flags;
}
/* try d_walk() in linux/fs/dcache.c */
int au_dcsub_pages(struct au_dcsub_pages *dpages, struct dentry *root,
au_dpages_test test, void *arg)
{
int err;
struct dentry *this_parent;
struct list_head *next;
struct super_block *sb = root->d_sb;
err = 0;
write_seqlock(&rename_lock);
this_parent = root;
spin_lock(&this_parent->d_lock);
repeat:
next = this_parent->d_subdirs.next;
resume:
if (this_parent->d_sb == sb
&& !IS_ROOT(this_parent)
&& au_di(this_parent)
&& d_count(this_parent)
&& (!test || test(this_parent, arg))) {
err = au_dpages_append(dpages, this_parent, GFP_ATOMIC);
if (unlikely(err))
goto out;
}
while (next != &this_parent->d_subdirs) {
struct list_head *tmp = next;
struct dentry *dentry = list_entry(tmp, struct dentry,
d_u.d_child);
next = tmp->next;
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
if (d_count(dentry)) {
if (!list_empty(&dentry->d_subdirs)) {
spin_unlock(&this_parent->d_lock);
spin_release(&dentry->d_lock.dep_map, 1,
_RET_IP_);
this_parent = dentry;
spin_acquire(&this_parent->d_lock.dep_map, 0, 1,
_RET_IP_);
goto repeat;
}
if (dentry->d_sb == sb
&& au_di(dentry)
&& (!test || test(dentry, arg)))
err = au_dpages_append(dpages, dentry,
GFP_ATOMIC);
}
spin_unlock(&dentry->d_lock);
if (unlikely(err))
goto out;
}
if (this_parent != root) {
struct dentry *tmp;
struct dentry *child;
tmp = this_parent->d_parent;
rcu_read_lock();
spin_unlock(&this_parent->d_lock);
child = this_parent;
this_parent = tmp;
spin_lock(&this_parent->d_lock);
rcu_read_unlock();
next = child->d_u.d_child.next;
goto resume;
}
out:
spin_unlock(&this_parent->d_lock);
write_sequnlock(&rename_lock);
return err;
}
void __lockfunc rt_spin_lock_nested(spinlock_t *lock, int subclass)
{
rt_spin_lock_fastlock(&lock->lock, rt_spin_lock_slowlock);
spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
}
void __lockfunc rt_spin_lock(spinlock_t *lock)
{
rt_spin_lock_fastlock(&lock->lock, rt_spin_lock_slowlock);
spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
}
void __lockfunc _raw_spin_lock_nested(raw_spinlock_t *lock, int subclass)
{
preempt_disable();
spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
}