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我有一个关于 Linux 内核设备节点的问题，创建的节点示例在同一个类中，但设备不同，但节点名称相同。如果我改变一个节点的值，另一个节点也会改变：如何防止这种情况发生？

例子：

echo '5' > /sys/class/myclass/mydevice/mydevice 
the value of sys/class/myclass/mydevice1/mydevice will also be changed to 5

#include <linux/module.h>
#include <linux/init.h>
#include <linux/sysfs.h>
#include <linux/string.h>
#include <linux/device.h>
#include <linux/fs.h>

static char mybuf[100] = "2";
static int major,major1;
static struct class *myclass;

static ssize_t mydevice_show(struct device *dev, struct device_attribute *attr,
        char *buf)
{
    return sprintf(buf, "%s\n", mybuf);
}
static ssize_t mydevice_store(struct device *dev, struct device_attribute *attr,
         const char *buf, size_t count)
{
    sprintf(mybuf, "%s", buf);

    return count;
}
static DEVICE_ATTR(mydevice, 0644, mydevice_show, mydevice_store);

static struct file_operations myfops = {
    .owner = THIS_MODULE,
};

static int __init mydevice_init(void)
{
    int ret;
    struct device *mydevice,*mydevice1;

    major = register_chrdev(0, "mydevice", &myfops);
    if (major < 0) {
        ret = major;
        return ret;
    }
    major1 = register_chrdev(0, "mydevice1", &myfops);
    if (major1 < 0) {
        ret = major1;
        return ret;
    }

    myclass = class_create(THIS_MODULE, "myclass");
    if (IS_ERR(myclass)) {
        ret = -EBUSY;
        goto fail;
    }

    mydevice = device_create(myclass, NULL, MKDEV(major, 0), NULL, "mydevice");
    if (IS_ERR(mydevice)) {
        class_destroy(myclass);
        ret = -EBUSY;
        goto fail;
    }

    mydevice1 = device_create(myclass, NULL, MKDEV(major1, 0), NULL, "mydevice1");
    if (IS_ERR(mydevice1)) {
        class_destroy(myclass);
        ret = -EBUSY;
        goto fail;
    }

    ret = sysfs_create_file(&mydevice->kobj, &dev_attr_mydevice.attr);
    ret = sysfs_create_file(&mydevice1->kobj, &dev_attr_mydevice.attr);
    if (ret < 0)
        return ret;

    return 0;

fail:
    unregister_chrdev(major, "mydevice");
    return ret;
}

static void __exit mydevice_exit(void)
{
    device_destroy(myclass, MKDEV(major, 0));
    device_destroy(myclass, MKDEV(major1, 0));
    class_destroy(myclass);
    unregister_chrdev(major, "mydevice");
    unregister_chrdev(major1, "mydevice1");
}

module_init(mydevice_init);
module_exit(mydevice_exit);

MODULE_DESCRIPTION("A simplest driver");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("HLY");
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1 回答 1

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这些设备共享同一个缓冲区。要修复它，请为每个设备使用单独的缓冲区。您可以使用dev_set_drvdata(device, mybuf);anddev_set_drvdata(device1, mybuf1);设置指向每个设备的单独缓冲区的指针，并使用dev_get_drvdata(dev)获取指向设备缓冲区的指针。

于 2021-10-13T12:24:50.393 回答