Here it is code snippets for easier review.
typedef struct timer_base_s {
spinlock_t lock;
struct timer_list *running_timer;
} timer_base_t;
struct tvec_t_base_s {
timer_base_t t_base;
...
} tvec_bases[];
struct timer_list {
...
timer_base_t *_base;
};
int timer_pending(struct timer_list * timer)
{
return timer->entry.next != NULL;
}
void init_timer(struct timer_list *timer)
{
timer->entry.next = NULL;
timer->_base = &per_cpu(tvec_bases).t_base;
}
timer_base_t *lock_timer_base(struct timer_list *timer, unsigned long *flags)
{
for (;;) {
timer_base_t *base = timer->_base;
if (base != NULL) {
spin_lock_irqsave(&base->lock, *flags);
if (base == timer->_base)
return base;
spin_unlock_irqrestore(&base->lock, *flags);
}
}
}
int __mod_timer(struct timer_list *timer, unsigned long expires)
{
timer_base_t *base;
tvec_base_t *new_base;
int ret = -1;
do {
base = lock_timer_base(timer, &flags);
new_base = &__get_cpu_var(tvec_bases);
/* Ensure the timer is serialized. */
if (base != &new_base->t_base
&& base->running_timer == timer)
goto unlock;
ret = 0;
if (timer_pending(timer)) {
__list_del(timer->entry);
ret = 1;
}
if (base != &new_base->t_base) {
timer->_base = NULL;
spin_unlock(&base->lock);
base = &new_base->t_base;
spin_lock(&base->lock);
timer->_base = base;
}
timer->expires = expires;
internal_add_timer(new_base, timer);
unlock:
spin_unlock_irqrestore(&base->lock, flags);
} while (ret < 0);
return ret;
}
void detach_timer(struct timer_list *timer)
{
__list_del(timer->entry);
entry->next = NULL;
}
int del_timer(struct timer_list *timer)
{
int ret = 0;
if (timer_pending(timer)) {
timer_base_t *base = lock_timer_base(timer);
if (timer_pending(timer)) {
detach_timer(timer);
ret = 1;
}
spin_unlock_irqrestore(&base->lock, flags);
}
return ret;
}
int del_timer_sync(struct timer_list *timer)
{
int ret = -1;
do {
timer_base_t *base = lock_timer_base(timer);
if (base->running_timer == timer)
goto unlock;
ret = 0;
if (timer_pending(timer)) {
detach_timer(timer);
ret = 1;
}
unlock:
spin_unlock_irqrestore(&base->lock, flags);
} while (ret < 0);
return ret;
}
void __run_timers(tvec_base_t *base)
{
spin_lock_irq(&base->t_base.lock);
for_each_expired_timer(timer) {
base->t_base.running_timer = timer;
detach_timer(timer);
spin_unlock(&base->t_base.lock);
timer->function(data);
spin_lock(&base->t_base.lock);
}
}
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