#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/sched.h>
MODULE_LICENSE("GPL");
static dev_t devnum;
static struct cdev *dev;
+static const char default_greeting[] = "Hello, World!\n";
+
+static DEFINE_SPINLOCK(hello_lock);
static int hello_open(struct inode *ino, struct file *fp)
{
- printk(KERN_DEBUG "Hello, World!\n");
+ return 0;
+}
+
+static ssize_t hello_read(struct file *fp, char __user *buf, size_t sz,
+ loff_t *pos)
+{
+ int i = 1 << 20;
+ while (i--)
+ udelay(10);
+ return 0;
+}
+
+static ssize_t hello_write(struct file *fp, const char __user *buf, size_t sz,
+ loff_t *pos)
+{
+ return 0;
+}
+
+static int hello_release(struct inode *ino, struct file *fp)
+{
return 0;
}
static const struct file_operations hello_fops = {
.owner = THIS_MODULE,
.open = hello_open,
+ .release = hello_release,
+ .read = hello_read,
+ .write = hello_write,
};
static int __init ch_init(void)
int r = 0;
r = alloc_chrdev_region(&devnum, 0, 256, "hello");
if (r)
- goto out;
+ goto reg_out;
dev = cdev_alloc();
if (!dev) {
r = -ENOMEM;
kfree(dev);
cdev_out:
unregister_chrdev_region(devnum, 256);
-out:
+reg_out:
return r;
}