Write a Linux kernel module to collect information of curren

Write a Linux kernel module to collect information of current running processes. When the kernel module is loaded, it should search for processes that has the highest number of children. It should build a Linux queue that includes the following details: parent process id child process id child command line current count of the child process Also, all these details should be printed to the system log. When the kernel module is unloaded, print this process id, command line and number of children processes. Also, remove the created linux queue. Your code should not use \"for_each_process: macro to check for children. Make sure you handle all cases, exceptions and cover possible user mistakes. You must submit a compressed file that contains: kernel module folder sample user program run output of the kernel log output of the \"ps\" command to support your answer

Solution

Kernel modules are piece of code, that can be loaded and unloaded from kernel on demand.

Kernel modules offers an easy way to extend the functionality of the base kernel without having to rebuild or recompile the kernel again. Most of the drivers are implemented as a Linux kernel modules. When those drivers are not needed, we can unload only that specific driver, which will reduce the kernel image size.

The kernel modules will have a .ko extension. On a normal linux system, the kernel modules will reside inside /lib/modules/<kernel_version>/kernel/ directory.

Earlier we discussed how to compile a kernel from the source.

This tutorial explains how to write a Kernel module using a simple Hello World example.

I. Utilities to Manipulate Kernel Modules

1. lsmod – List Modules that Loaded Already

lsmod command will list modules that are already loaded in the kernel as shown beblow.

2. insmod – Insert Module into Kernel

insmod command will insert a new module into the kernel as shown below.

3. modinfo – Display Module Info

modinfo command will display information about a kernel module as shown below.

4. rmmod – Remove Module from Kernel

rmmod command will remove a module from the kernel. You cannot remove a module which is already used by any program.

5. modprobe – Add or Remove modules from the kernel

modprobe is an intelligent command which will load/unload modules based on the dependency between modules. Refer to modprobe commands for more detailed examples.

II. Write a Simple Hello World Kernel Module

1. Installing the linux headers

You need to install the linux-headers-.. first as shown below. Depending on your distro, use apt-get or yum.

2. Hello World Module Source Code

Next, create the following hello.c module in C programming language.