void        (*ack)(unsigned int irq);
    void        (*mask)(unsigned int irq);
    void        (*mask_ack)(unsigned int irq);
    void        (*unmask)(unsigned int irq);
    void        (*eoi)(unsigned int irq);

    void        (*end)(unsigned int irq);
    void        (*set_affinity)(unsigned int irq, cpumask_t dest);
    int        (*retrigger)(unsigned int irq);
    int        (*set_type)(unsigned int irq, unsigned int flow_type);
    int        (*set_wake)(unsigned int irq, unsigned int on);

    /* Currently used only by UML, might disappear one day.*/
#ifdef CONFIG_IRQ_RELEASE_METHOD
    void        (*release)(unsigned int irq, void *dev_id);
#endif
    /*
    * For compatibility, ->typename is copied into ->name.
    * Will disappear.
    */
    const char    *typename;
};

irq_desc结构中的irqaction结构类型在include/linux/iterrupt.h中定义。用户注册的每个中断处理函数用一个irqaction结构来表示，一个中断比如共享中断可以有多个处理函数，它们的irqaction结构链接成一个链表，以action为表头。irqation结构在linux/include/linux/interrupt.h中定义如下：

typedef irqreturn_t (*irq_handler_t)(int, void *);

struct irqaction {
    irq_handler_t handler;
    unsigned long flags;
    cpumask_t mask;
    const char *name;
    void *dev_id;
    struct irqaction *next;
    int irq;
    struct proc_dir_entry *dir;
};

 irq_desc结构数组、它的成员“struct irq_chip *chip” "struct irqaction *action",这3种数据结构构成了中断处理体系的框架。下图中描述了Linxu中断处理体系结构的关系图：