lockdep状态相关定义如LOCK_ENABLED_HARDIRQ

1. LOCK_ENABLED_HARDIRQ定义在哪？

诸多上下文状态如LOCK_ENABLED_HARDIRQ等直接搜索没看到定义。它的定义在头文件lockdep_internals.h中，而lockdep_internals.h引用的头文件是lockdep_states.h。

• lockdep_internals.h
• lockdep_states.h

2. HARDIRQ和SOFTIRQ

lockdep_internals.h文件中定义了很多型如下面宏定义的数据结构：

#define LOCKDEP_STATE(__STATE) //定义
....
#include "lockdep_states.h"   //包含
#undef LOCKDEP_STATE          //取消定义

都是“定义 > 包含 > 取消定义” 》“定义 > 包含 > 取消定义” 》…

2.1 基础枚举型 enum lock_usage_bit

看第一个例子：enum lock_usage_bit

enum lock_usage_bit {
#define LOCKDEP_STATE(__STATE)		\LOCK_USED_IN_##__STATE,		\LOCK_USED_IN_##__STATE##_READ,	\LOCK_ENABLED_##__STATE,		\LOCK_ENABLED_##__STATE##_READ,
#include "lockdep_states.h"
#undef LOCKDEP_STATELOCK_USED,LOCK_USAGE_STATES
};

将lockdep_states.h两行包含进来：

LOCKDEP_STATE(HARDIRQ)
LOCKDEP_STATE(SOFTIRQ)

变成：

enum lock_usage_bit {
#define LOCKDEP_STATE(__STATE)		\LOCK_USED_IN_##__STATE,			\LOCK_USED_IN_##__STATE##_READ,	\LOCK_ENABLED_##__STATE,			\LOCK_ENABLED_##__STATE##_READ,LOCKDEP_STATE(HARDIRQ)			//(1)LOCKDEP_STATE(SOFTIRQ)			//(2)
#undef LOCKDEP_STATELOCK_USED,LOCK_USAGE_STATES
};

(1) 和 (2)分别展开也即__STATE分别替换成HARDIRQ和SOFTIRQ：

/** Lock-class usage-state bits:*/
enum lock_usage_bit {LOCK_USED_IN_HARDIRQ,	LOCK_USED_IN_HARDIRQ_READ,	LOCK_ENABLED_HARDIRQ,LOCK_ENABLED_HARDIRQ_READ,LOCK_USED_IN_SOFTIRQ,	LOCK_USED_IN_SOFTIRQ_READ,	LOCK_ENABLED_SOFTIRQ,LOCK_ENABLED_SOFTIRQ_READ,LOCK_USED,LOCK_USAGE_STATES
};

这个是基础，其他枚举或宏均基于这个枚举。

2.2 Usage-state bitmasks

/** Usage-state bitmasks:*/
enum {LOCKF_USED_IN_HARDIRQ =  (1 << LOCK_USED_IN_HARDIRQ),LOCKF_USED_IN_HARDIRQ_READ =  (1 << LOCK_USED_IN_HARDIRQ_READ),LOCKF_ENABLED_HARDIRQ =  (1 << LOCK_ENABLED_HARDIRQ),LOCKF_ENABLED_HARDIRQ_READ =  (1 << LOCK_ENABLED_HARDIRQ_READ),LOCKF_USED_IN_SOFTIRQ =  (1 << LOCK_USED_IN_SOFTIRQ),LOCKF_USED_IN_SOFTIRQ_READ =  (1 << LOCK_USED_IN_SOFTIRQ_READ),LOCKF_ENABLED_SOFTIRQ =  (1 << LOCK_ENABLED_SOFTIRQ),LOCKF_ENABLED_SOFTIRQ_READ =  (1 << LOCK_ENABLED_SOFTIRQ_READ),LOCKF_USED = (1 << LOCK_USAGE_STATES),
};static const unsigned long LOCKF_ENABLED_IRQ = LOCKF_ENABLED_HARDIRQ | LOCKF_ENABLED_SOFTIRQ | 0;
static const unsigned long LOCKF_USED_IN_IRQ = LOCKF_USED_IN_HARDIRQ | LOCKF_USED_IN_SOFTIRQ | 0;
static const unsigned long LOCKF_ENABLED_IRQ_READ = LOCKF_ENABLED_HARDIRQ_READ | LOCKF_ENABLED_SOFTIRQ_READ | 0;
static const unsigned long LOCKF_USED_IN_IRQ_READ = LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ | 0;