THIS_MODULE in Linux Device Drivers

What is THIS_MODULE?

Whenever you create a kernel module, the kernel's build machinery generates a struct module object for you, and makes THIS_MODULE point to it.

This struct contains many fields, some of which can be set with module macros such as MODULE_VERSION.

You can see from the definition of THIS_MODULE macro that it is referring to '__this_module'. This is defined when we build the module file by running 'make'

Let's write a sample module which prints the module name and version using THIS_MODULE.

	#include <linux/module.h>
	#include <linux/kernel.h>
	extern struct module __this_module;
	static int myinit(void)
	{
	/* Set by default based on the module file name. */
	pr_info("name = %s\n", THIS_MODULE->name);
	pr_info("version = %s\n", THIS_MODULE->version);
	pr_info("version = %s\n", (&__this_module)->version);
	return 0;
	}
	static void myexit(void) {}
	module_init(myinit)
	module_exit(myexit)
	MODULE_VERSION("1.0");
	MODULE_LICENSE("GPL");

view raw this_module_test.c hosted with ❤ by GitHub

Output:

You can see from the above screenshot, after running "make", it generated temporary files as well as the module(.ko). The *.mod.c file has struct module __this_module defined.