linux内核原子变量与原子位操作API

原子变量:
arch/arm/include/asm/atomic.h

定义并初始化
atomic_t v = ATOMIC_INIT(0);

写
void atomic_set(atomic_t *v, int i);

读
int atomic_read(atomic_t *v);

自增, 并返回新值是否为0
int atomic_inc_and_test(atomic_t *v);

自减, 并返回新值是否为0
int atomic_dec_and_test(atomic_t *v);

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原子位:
arch/arm/include/asm/bitops.h:204

操作从地址p开始下标为nr(0 --> 0xffffffff)的位

void set_bit(unsigned int nr, unsigned long *p);
void clear_bit(unsigned int nr, unsigned long *p);
void change_bit(unsigned int nr, unsigned long *p);

int test_and_set_bit(unsigned int nr, unsigned long *p);
int test_and_clear_bit(unsigned int nr, unsigned long *p);
int test_and_change_bit(unsigned int nr, unsigned long *p);
test函数返回旧值