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读写锁分为spinlock 类型和信号量类型首先看spinlock类型其中spinlock类型的读写锁定义在include/linux/rwlock_types.h其结构定义如下：typedef struct {	arch_rwlock_t raw_lock;#ifdef CONFIG_DEBUG_SPINLOCK	unsigned int magic, owner_cpu;	void *owner;#endif#ifdef CONFIG_DEBUG_LOCK_ALLOC	struct lockdep_map dep_map;#endif} rwlock_t;可以看出出去debug的config 后rwlock_t就等于下面的结构typedef struct {	arch_rwlock_t raw_lock;} rwlock_t;读写spinlock的API 都定义在include/linux/rwlock.h 中例如在使用读写spinlock锁时候，首先初始化# define rwlock_init(lock)					\do {								\	static struct lock_class_key __key;			\								\	__rwlock_init((lock), #lock, &__key);			\} while (0)然后是读锁的lock 和 unlockread_lock()read_unlock()其次是写锁的lock 和 unlockwrite_lock（）write_unlock剩下就是spinlock锁有的API在rwlock这边都会有，例如read_lock_irq/write_lock_irq等其次是读写信号量锁其定义在include/linux/rwsem.h中#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK#include 
   
     /* use a generic implementation */#define __RWSEM_INIT_COUNT(name)	.count = RWSEM_UNLOCKED_VALUE#else/* All arch specific implementations share the same struct */struct rw_semaphore {	atomic_long_t count;	struct list_head wait_list;	raw_spinlock_t wait_lock;#ifdef CONFIG_RWSEM_SPIN_ON_OWNER	struct optimistic_spin_queue osq; /* spinner MCS lock */	/*	 * Write owner. Used as a speculative check to see	 * if the owner is running on the cpu.	 */	struct task_struct *owner;#endif#ifdef CONFIG_DEBUG_LOCK_ALLOC	struct lockdep_map	dep_map;#endif};其初始化为#define init_rwsem(sem)						\do {								\	static struct lock_class_key __key;			\								\	__init_rwsem((sem), #sem, &__key);			\} while (0)对应的读锁的lock和unlockdown_read （）up_read（）写锁的lock和unlockdown_write()up_write()
   

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