1 files changed, 90 insertions, 0 deletions
diff --git a/sleep/sleep.c b/sleep/sleep.c
new file mode 100644
index 0000000..3cc06e8
--- /dev/null
+++ b/sleep/sleep.c
@@ -0,0 +1,90 @@
+#include <asm/uaccess.h>
+#include <linux/cdev.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/kdev_t.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/wait.h>
+
+static char devname[] = "sleep";
+static char modname[] = "sleep.ko";
+static dev_t mydev = 0;
+static struct cdev cdev;
+static int count = 0;
+
+DECLARE_WAIT_QUEUE_HEAD(myqueue);
+
+int sleep_open(struct inode *i, struct file *filp)
+{
+	printk(KERN_ALERT "sleep_open: device (%d-%d) opened\n",
+			imajor(i), iminor(i));
+	printk(KERN_ALERT "sleep_open: mode %c%c\n", filp->f_mode & FMODE_READ ?
+			'R' : '-', filp->f_mode & FMODE_WRITE ? 'W' : '-');
+	return 0;
+}
+
+ssize_t sleep_read(struct file *filp, char __user *buf, size_t len,
+		loff_t *offset)
+{
+	printk(KERN_ALERT "sleep_read: putting process %d (%s) to sleep...\n",
+			current->pid, current->comm);
+	count = 0;
+	if (wait_event_interruptible(myqueue, count))
+		return -ERESTARTSYS;
+	return 0;
+}
+
+ssize_t sleep_write(struct file *filp, const char __user *buf, size_t len,
+		loff_t *offset)
+{
+	printk(KERN_ALERT "sleep_write: process %d (%s) brings salvation :D\n",
+			current->pid, current->comm);
+	count = 1;
+	wake_up_interruptible(&myqueue);
+	return -EPERM;
+}
+
+struct file_operations fops = {
+	.owner = THIS_MODULE,
+	.open = sleep_open,
+	.read = sleep_read,
+	.write = sleep_write,
+};
+
+static int __init sleep_init(void)
+{
+	int err;
+
+	printk(KERN_ALERT "sleep_init: %s loaded by %s (%d)\n",
+			modname, current->comm, current->pid);
+
+	if ((err = alloc_chrdev_region(&mydev, 0, 1, devname)))
+		printk(KERN_ALERT "sleep_init: error %d in alloc_chrdev_region\n", err);
+	else
+		printk(KERN_ALERT "sleep_init: %s successfully registered with "
+				"%d %d numbers\n", devname, MAJOR(mydev), MINOR(mydev));
+
+	cdev_init(&cdev, &fops);
+	cdev.owner = THIS_MODULE;
+	if ((err = cdev_add(&cdev, mydev, 1)))
+		printk(KERN_ALERT "sleep_init: error %d in cdev_add\n", err);
+
+	return 0;
+}
+
+static void __exit sleep_exit(void)
+{
+	unregister_chrdev_region(mydev, 1);
+	cdev_del(&cdev);
+	printk(KERN_ALERT "sleep_exit: %s unloaded\n", modname);
+}
+
+module_init(sleep_init);
+module_exit(sleep_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Guillermo Ramos");