Mastering Linux Kernel Development

Dynamic timers

Dynamic timers can be created and destroyed at any time, hence the name dynamic timers. Dynamic timers are represented by the struct timer_list object, defined in include/linux/timer.h:

struct timer_list {
        /*
        * Every field that changes during normal runtime grouped to the
        * same cacheline
        */
        struct hlist_node entry;
        unsigned long           expires;
        void                    (*function)(unsigned long);
        unsigned long           data;
        u32                      flags;

#ifdef CONFIG_LOCKDEP
        struct lockdep_map        lockdep_map;
#endif
};

All timers in a system are managed by a doubly linked list, and are sorted in order of their expiry time, represented by the expires field. The expires field specifies the time duration, after which the timer expires. As soon as the current jiffies value matches ...