Notes on checkpatch

README.md

@@ -12,3 +12,7 @@
 ### Insert & remove
 `sudo insmod demo_module.ko`
 `sudo rmmod demo_module.ko`
+
+### Style
+Check for style with:  
+`${LINUX_PATH}/scripts/checkpatch.pl -f ./file.c`

ioctl_chardev/my-ioctl.c

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0
+
 #include <linux/device.h>
 #include "my-ioctl.h"
 
@@ -14,7 +16,7 @@ static struct class *cls;
 static long my_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
 
 /* See: https://elixir.bootlin.com/linux/v6.14.5/source/include/linux/fs.h#L2131 */
-static struct file_operations fops = {
+static const struct file_operations fops = {
 	.owner = THIS_MODULE,
 	.unlocked_ioctl = my_ioctl,
 };

ioctl_chardev/my-ioctl.h

@@ -1,14 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
 #ifndef MY_IOCTL_H
 #define MY_IOCTL_H
 #include <linux/ioctl.h>
 
 /*
  * Crucial point here, the kernel defines a set of macros for defining IOCTL numbers:
- * 	_IO - No command
+ *	_IO - No command
- * 	_IOR - Read command
+ *	_IOR - Read command
- * 	_IOW - Write command
+ *	_IOW - Write command
- * 	_IORW - RW command
+ *	_IORW - RW command
- * 	_IOC - Basis of the others
+ *	_IOC - Basis of the others
  * These macros encode the data type passed to the ioctl.
  */
 

ioctl_chardev/test.c

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0
+
 #include <stdio.h>
 // #include <stdlib.h>
 #include <unistd.h>