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put back error checking

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Yaakov 2024-08-11 17:49:35 +10:00
parent 36e804b1f3
commit 5c61c12fdb
1 changed files with 40 additions and 11 deletions
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51
scream.c
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@ -23,41 +23,70 @@ static int scream_device_release(struct inode*, struct file*);
static ssize_t scream_device_read(struct file*, char*, size_t, loff_t*); static ssize_t scream_device_read(struct file*, char*, size_t, loff_t*);
static const struct file_operations scream_fops = { static const struct file_operations scream_fops = {
.owner = THIS_MODULE, .owner = THIS_MODULE,
.open = scream_device_open, .open = scream_device_open,
.read = scream_device_read, .read = scream_device_read,
.release = scream_device_release, .release = scream_device_release,
}; };
static int __init scream_module_init(void) static int __init scream_module_init(void) {
{
printk(KERN_INFO "[scream] loading...\n");
int err; int err;
dev_t dev; dev_t dev;
err = alloc_chrdev_region(&dev, 0, 1, DEVICE_NAME); err = alloc_chrdev_region(&dev, 0, 1, DEVICE_NAME);
if (err) {
printk(KERN_ALERT "[scream] Failed to register a major number.\n");
return err;
}
major_number = MAJOR(dev); major_number = MAJOR(dev);
scream_class = class_create(CLASS_NAME); scream_class = class_create(CLASS_NAME);
if (IS_ERR(scream_class)) {
unregister_chrdev_region(major_number, 1);
printk(KERN_ALERT "[scream] Failed to register device class\n");
return PTR_ERR(scream_class);
}
scream_device = device_create(scream_class, NULL, MKDEV(major_number, 0), NULL, DEVICE_NAME);
if (IS_ERR(scream_device)) {
class_destroy(scream_class);
unregister_chrdev_region(major_number, 1);
printk(KERN_ALERT "[scream] Failed to create the device\n");
return PTR_ERR(scream_device);
}
printk(KERN_INFO "[scream] %s/%s device registered.", CLASS_NAME, DEVICE_NAME);
cdev_init(&scream_cdev, &scream_fops); cdev_init(&scream_cdev, &scream_fops);
scream_cdev.owner = THIS_MODULE; err = cdev_add(&scream_cdev, MKDEV(major_number, 0), 1);
if (err < 0) {
cdev_add(&scream_cdev, MKDEV(major_number, 0), 1); device_destroy(scream_class, MKDEV(major_number, 0));
class_destroy(scream_class);
device_create(scream_class, NULL, MKDEV(major_number, 0), NULL, DEVICE_NAME); unregister_chrdev_region(major_number, 1);
printk(KERN_ALERT "[scream] Failed to add cdev: %d\n", err);
return err;
}
printk(KERN_INFO "[scream] loaded.\n");
return 0; return 0;
} }
static void __exit scream_module_exit(void) static void __exit scream_module_exit(void)
{ {
printk(KERN_INFO "[scream] exiting...\n");
cdev_del(&scream_cdev);
device_destroy(scream_class, MKDEV(major_number, 0)); device_destroy(scream_class, MKDEV(major_number, 0));
class_unregister(scream_class);
class_destroy(scream_class); class_destroy(scream_class);
unregister_chrdev_region(major_number, 1);
unregister_chrdev_region(MKDEV(major_number, 0), MINORMASK); printk(KERN_INFO "[scream] done.\n");
} }
static int scream_device_open(struct inode *inode, struct file *file) static int scream_device_open(struct inode *inode, struct file *file)