debugfs中私有数据的使用

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

struct dentry *test_dentry;

struct PrivateInfo {
	int id;
	char tmp[20];
};

static struct PrivateInfo info = {
	.id = 25,
	.tmp = "hello world",
};

int demo_open(struct inode *inode, struct file *file)
{
	struct PrivateInfo *pInfo;

	pr_info("%s, ===>n", __func__);
	file->private_data = inode->i_private;
	if (IS_ERR_OR_NULL(file->private_data)) {
		pr_err("%s, file->private_data invalidn", __func__);
		return -EFAULT;
	}

	pInfo = (struct PrivateInfo*)(file->private_data);

	pr_info("%s, id %d, tmp %sn", __func__, pInfo->id, pInfo->tmp);
	pr_info("%s, <===n", __func__);
	return 0;
}

int demo_release(struct inode *inode, struct file *file)
{
	struct PrivateInfo *pInfo;

	pr_info("%s, ===>n", __func__);
	file->private_data = inode->i_private;
	if (IS_ERR_OR_NULL(file->private_data)) {
		pr_err("%s, file->private_data invalidn", __func__);
		return -EFAULT;
	}

	pInfo = (struct PrivateInfo*)(file->private_data);

	pr_info("%s, id %d, tmp %sn", __func__, pInfo->id, pInfo->tmp);
	pr_info("%s, <===n", __func__);
	return 0;
}

static const struct file_operations demo_fops = {
	.open  = demo_open,
	.release  = demo_release,
};

static int __init my_demo_init(void)
{
	pr_info("%s, ===>n", __func__);
	pr_info("%s, before debugfs create filen", __func__);
	// 这里一定是 (void *)&info
	test_dentry = (struct dentry *)debugfs_create_file("debug_demo", 0666, NULL, (void *)&info, &demo_fops);
	if (IS_ERR_OR_NULL(test_dentry)) {
		pr_err("%s, debugfs create file failedn", __func__);
	} else {
		pr_info("%s, debugfs create file successn", __func__);
	}
	pr_info("%s, <===n", __func__);
	return 0;
}

static void my_demo_exit(void)
{
	pr_info("%s, ===>n", __func__);
	if (IS_ERR_OR_NULL(test_dentry)) {
		pr_err("%s, debugfs is invalidn", __func__);
	} else {
		debugfs_remove(test_dentry);
		test_dentry = NULL;
		pr_info("%s, debugfs remove successn", __func__);
	}
	pr_info("%s, <===n", __func__);
}

module_init(my_demo_init);
module_exit(my_demo_exit);

MODULE_LICENSE ("GPL");
MODULE_AUTHOR ("kiss1994");
MODULE_DEscriptION ("debugfs");

#include 
#include 
#include 
#include 
#include 
#include 
#include 

int main() {
	char *filename = "/sys/kernel/debug/debug_demo";
	int fd = open(filename,O_RDWR);
	if(fd<0){
		perror("open fail n");
		return -1;
	}
	printf("open file %s success!n", filename);
	sleep(3);
	close(fd);
	printf("close file %s success!n", filename);
	return 0;
}

[ 4215.441563] my_demo_init, ===>
[ 4215.441568] my_demo_init, before debugfs create file
[ 4215.441595] my_demo_init, debugfs create file success
[ 4215.441596] my_demo_init, <===

[ 4471.569330] demo_open, ===>
[ 4471.569338] demo_open, id 25, tmp hello world
[ 4471.569340] demo_open, <===

[ 4474.570193] demo_release, ===>
[ 4474.570202] demo_release, id 25, tmp hello world
[ 4474.570204] demo_release, <===

[ 4489.417556] my_demo_exit, ===>
[ 4489.417725] my_demo_exit, debugfs remove success
[ 4489.417728] my_demo_exit, <===

//=======================================================

struct dentry *debugfs_create_file(const char *name, umode_t mode,
				   struct dentry *parent, void *data,
				   const struct file_operations *fops)
{

	return __debugfs_create_file(name, mode, parent, data,
				fops ? &debugfs_full_proxy_file_operations :
					&debugfs_noop_file_operations,
				fops);
}
EXPORT_SYMBOL_GPL(debugfs_create_file);

void debugfs_remove(struct dentry *dentry)
{
	if (IS_ERR_OR_NULL(dentry))
		return;

	simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count);
	simple_recursive_removal(dentry, remove_one);
	simple_release_fs(&debugfs_mount, &debugfs_mount_count);
}
EXPORT_SYMBOL_GPL(debugfs_remove);