內核定時機制－－setup_timer

#define setup_timer(timer, fn, data)                    \
     __setup_timer((timer), (fn), (data), 0)

#define __setup_timer(_timer, _fn, _data, _flags)           \
    do {                                \
        __init_timer((_timer), (_flags));           \
        (_timer)->function = (_fn);             \
        (_timer)->data = (_data);               \
    } while (0)

#ifdef CONFIG_LOCKDEP
#define __init_timer(_timer, _flags)                    \
    do {                                \
        static struct lock_class_key __key;         \
        init_timer_key((_timer), (_flags), #_timer, &__key);    \
    } while (0)

#define __init_timer_on_stack(_timer, _flags)               \
    do {                                \
        static struct lock_class_key __key;         \
        init_timer_on_stack_key((_timer), (_flags), #_timer, &__key); \
    } while (0)
#else
#define __init_timer(_timer, _flags)                    \
    init_timer_key((_timer), (_flags), NULL, NULL)
#define __init_timer_on_stack(_timer, _flags)               \
    init_timer_on_stack_key((_timer), (_flags), NULL, NULL)
#endif
CONFIG_LOCKDEP用於檢測死鎖，常用debug，這裏假定沒有開這個宏
所以這裏的又會轉調init_timer_key
void init_timer_key(struct timer_list *timer, unsigned int flags,
            const char *name, struct lock_class_key *key)
{
    debug_init(timer);
    do_init_timer(timer, flags, name, key);
}
設置定時的相關參數．
static void do_init_timer(struct timer_list *timer, unsigned int flags,
              const char *name, struct lock_class_key *key)
{
    timer->entry.pprev = NULL; //pprev 爲null，說明這個timer處於pending狀態，當然了剛開始創建timer的時候當然要pending了，畢竟還沒有開始執行
    timer->flags = flags | raw_smp_processor_id(); 
    timer->slack = -1;   
#ifdef CONFIG_TIMER_STATS
    timer->start_site = NULL;
    timer->start_pid = -1;
    memset(timer->start_comm, 0, TASK_COMM_LEN);
#endif
    lockdep_init_map(&timer->lockdep_map, name, key, 0);
} 
總結：
    主要回調，和數據賦值給第一個數timer，就是構造回調函數
    (_timer)->function = (_fn);             
    (_timer)->data = (_data);