Question

我已经阅读了很多关于同一主题的帖子，但是我无法找到我的内核模块中我的sysfs实现的确切错误。我试图在轮询上创建一个用户空间程序块，直到sysfs文件中的值更改。大多数人似乎都没有阻挡，我似乎无法摆脱阻挡。以下是相关代码：

内核模块：

static int sysfs_test = 88;


static ssize_t test_interrupts_show(struct device* dev, struct device_attribute* attr, const     char* buf)
{
    return scnprintf(buf, PAGE_SIZE, "%d\n", sysfs_test);
}

static ssize_t test_interrupts_store(struct device* dev, struct device_attribute* attr, const char* buf, size_t count)
{
    kstrtol(buf, 10, &sysfs_test);
    return count;
}

static DEVICE_ATTR(interrupts, S_IWUSR | S_IRUGO, test_interrupts_show, test_interrupts_store);

static int __init test_init(void)
{

int result;
if(dev_major)
{
    dev = MKDEV(dev_major, dev_minor);
    result = register_chrdev_region(dev, NUM_DEVICES, name);
} else {
    result = alloc_chrdev_region(&dev, dev_minor, NUM_DEVICES, name);
    dev_major = MAJOR(dev);
    dev_minor = MINOR(dev);
}

if(result < 0) {
    printk(KERN_WARNING "%s: can't get major %d\n", name, dev_major);
    return -1;
}
printk(KERN_NOTICE "%s: Major = %d, Minor = %d\n", name, dev_major, dev_minor);





// Register as character device
test_cdev = cdev_alloc();               
cdev_init(cajun_cdev, &test_fops);      // Initialize cdev structure
test_cdev->owner = THIS_MODULE;         // Add owner

result = cdev_add(test_cdev, dev,1);        // Tell kernel about our device

if(result)
{
    printk(KERN_NOTICE "Error %d adding cdev\n", result);
    goto OUT2;
}




// This stuff relates to sysfs:
ctest_class = class_create(THIS_MODULE, NAME);
if(IS_ERR(test_class))
{
    printk(KERN_ALERT "Failed to register device class\n");
    goto OUT2;
}

test_device = device_create(test_class, NULL, dev, NULL, NAME);
if(IS_ERR(test_device))
{
    printk(KERN_ALERT "Failed to create device\n");
    goto OUT3;
}

result = device_create_file(test_device, &dev_attr_interrupts);
if (result < 0)
{
    printk(KERN_ALERT "failed\n");
}



OUT3:
class_unregister(test_class);
class_destroy(test_class);
OUT2:
cdev_del(test_cdev);
OUT1:
unregister_chrdev_region(dev, NUM_DEVICES);

return -1;

}

重新发布用户空间代码：

char interrupts_path[] = "/sys/class/test_module/test_module/interrupts";

int main()
{
struct pollfd fds;
fds.fd = open(interrupts_path, O_RDWR | O_SYNC);
char dummy_buff[1];
read(fds.fd, dummy_buff, 1);
lseek(fds.fd, 0, SEEK_SET);
fds.events = POLLPRI;
printf("Polling for interrupt\n");
poll(&fds,1,-1);
printf("Interrupt occured\n");

return 0;
}

我在后台运行我的用户空间代码（./test &）然后我将一个新值回显到sysfs文件中以获取中断。我正在跳过我的用户空间程序来取消阻止并在值发生变化时返回。我在这做错了什么？

编辑：

struct file_operations test_fops = {
    .owner              =   THIS_MODULE,
    .llseek             =   test_llseek,
    .read               =   test_read,
    .write              =   test_write,
    .unlocked_ioctl     =   test_ioctl,
    .open               =   test_open,
    .release            =   test_release

};

轮询sysfs和内核模块

0 个答案: