一：设备驱动层
struct x_dev{
...
struct fasync_struct *async;
};
/*fasync函数*/
static int x_fasync(int fd, struct file *filp, int mode)
{
struct x_dev *dev = filp->private_data;
return fasync_helper(fd, filp, mode, &dev->async);
}
/*添加到 file_operations*/
static const struct file_operations x_fops = { ... .fasync = x_fasync, .... };
/*读写函数中释放信号*/
struct x_dev *dev = filp->private_data;
if(dev->async)
kill_fasync(&dev->async, SIGIO, POLL_IN(或者POLL_OUT));
/*release函数中删除*/
x_fasync(-1, filp, 0 );
二：用户空间
static void signal_handler(int signum)
{
}
void main(void)
{
int fd, flag;
fd = open("/dev/xx", O_RDWR, S_IRUSR | S_IWUSR);
signal(SIGIO, signal_handler);
fcntl(fd, F_SETOWN, getpid());
flag = fcntl(fd, F_GETFL);
fcntl(fd, F_SETFL, flag | FASYNC);
while(1);
}
