Linux 中断系统中的重要数据结构

Linux中断系统中的重要数据结构

可以从 request_irq(include/linux/interrupt.h) 函数一路分析得到

能弄清楚下面这个图，对Linux 中断系统的掌握也基本到位了

最核心的结构体是 irq_desc，之前为了易于理解，我们说在 Linux 内核中有一个中断数组，对于每一个硬件中断，都有一个数组项，这个数组就是 irq_desc 数组

struct irq_desc {
   
   
	struct irq_common_data	irq_common_data;
	struct irq_data		irq_data;
	unsigned int __percpu	*kstat_irqs;
	irq_flow_handler_t	handle_irq;
#ifdef CONFIG_IRQ_PREFLOW_FASTEOI
	irq_preflow_handler_t	preflow_handler;
#endif
	struct irqaction	*action;	/* IRQ action list */
	unsigned int		status_use_accessors;
	unsigned int		core_internal_state__do_not_mess_with_it;
	unsigned int		depth;		/* nested irq disables */
	unsigned int		wake_depth;	/* nested wake enables */
	unsigned int		tot_count;
	unsigned int		irq_count;	/* For detecting broken IRQs */
	unsigned long		last_unhandled;	/* Aging timer for unhandled count */
	unsigned int		irqs_unhandled;
	atomic_t		threads_handled;
	int			threads_handled_last;
	raw_spinlock_t		lock;
	struct cpumask		*percpu_enabled;
	const struct cpumask	*percpu_affinity;
#ifdef CONFIG_SMP
	const struct cpumask	*affinity_hint;
	struct irq_affinity_notify *affinity_notify;
#ifdef CONFIG_GENERIC_PENDING_IRQ
	cpumask_var_t		pending_mask;
#endif
#endif
	unsigned long		threads_oneshot;
	atomic_t		threads_active;
	wait_queue_head_t       wait_for_threads;
#ifdef CONFIG_PM_SLEEP
	unsigned int		nr_actions;
	unsigned int		no_suspend_depth;
	unsigned int		cond_suspend_depth;
	unsigned int		force_resume_depth;
#endif
#ifdef CONFIG_PROC_FS
	struct proc_dir_entry	*dir;
#endif
#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
	struct dentry		*debugfs_file;
	const char		*dev_name;
#endif
#ifdef CONFIG_SPARSE_IRQ
	struct rcu_head		rcu;
	struct kobject		kobj;
#endif
	struct mutex		request_mutex;
	int			parent_irq;
	struct module		*owner;
	const char		*name;
} ____cacheline_internodealigned_in_smp;

**注意：**如果内核配置了 CONFIG_SPARSE_IRQ，那么它就会用基数树 radix tree 来代替 irq_desc数组。SPARSE 的意思是 “稀疏”的情况下可以用基数树来代替数组

irq_desc数组

irq_desc结构体在 include/linux/irqdesc.h 中定义，主要内容如下（简化上面）：

struct irq_desc {
   
   
    // ...
	struct irq_data		irq_data;
	irq_flow_handler_t	handle_irq;
    const char		*name;
	struct irqaction	*action;	/* IRQ action list */
    // ...
} ____cacheline_internodealigned_in