linux kernel set_bit() 函数解析

将一个指针指向的数据的第nr位置一。

example:

__set_bit(EV_KEY, input_dev->evbit);
__set_bit(EV_ABS, input_dev->evbit);
__set_bit(BTN_TOUCH, input_dev->keybit);
__set_bit(INPUT_PROP_DIRECT, input_dev->propbit);

函数位于： kernel\include\asm-generic\bitops\non-atomic.h

/**

 * __set_bit - Set a bit in memory
 * @nr: the bit to set
 * @addr: the address to start counting from
 *
 * Unlike set_bit(), this function is non-atomic and may be reordered.
 * If it's called on the same region of memory simultaneously, the effect
 * may be that only one operation succeeds.
 */
static inline void __set_bit(int nr, volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);


*p  |= mask;
}