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CS4560 Operating Systems
Programming Project #2
 Due date: April 14 (Friday), 2017
 The file name of your reports have to be formatted as
CS4560_Project_n_xxxxxxx.docx (or .pdf) where n is the
project id and xxxxxxx is your student id ).
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Spring 2017
Operating Systems
Project Description
Refer to the textbook for Chapter 3 Programming Project: Linux Kernel Module for
Listing Tasks on page 159 of the 9th edition.
In this project, you will write a kernel module that lists all current tasks in a Linux
system. Be sure to review the programming project in Chapter 2, which deals with creating Linux
kernel modules, before you begin this project. The project can be completed using the Linux
virtual machine provided with this text. The instructions are posted at the textbook companion
web site http://www.os-book.com/.)
Part I –Iterating over Tasks Linearly
Design a kernel module that iterates through all tasks in the system using the for each process()
macro. In particular, output the task name (known as executable name), state, and process id of
each task. Follow the instructions on the textbook and do the following.
 Compile and run the program given below.
 Take screen shots of the output of your program (saved in the kernel log
 Find and run the Linux command to list all the processes.
 Please discuss how different or similar the outputs of your program and the Linux
command.
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
char* msg[] = {"RUNNING","INTERRUPTIBLE","UNINTERRUPTIBLE", "ZOMBIE",
"STOPPED"};
/* performs a depth-first traversal of the list of tasks in the system. */
void traverse(struct task_struct *ptr) {
struct list_head *list;
struct task_struct *next_task;
if (thread_group_leader(ptr))
printk(KERN_INFO ">>>name = %s, id=%d, state=%s<<<\n",
ptr->comm, ptr->pid, msg[ptr->state]);
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list_for_each(list, &ptr->children) {
next_task = list_entry(list, struct task_struct, sibling);
traverse(next_task);
}
}
int simple_init(void)
{
bool partI = true ; // change it to false for partII
printk(KERN_INFO "Loading Module\n");
if ( partI ) {
struct task_struct *ptr;
for_each_process(ptr) {
printk(KERN_INFO ">>>name = %s, id=%d, state=%s<<<\n",
ptr->comm, ptr->pid, msg[ptr->state]);
}
} else {
traverse(&init_task);
}
return 0;
}
void simple_exit(void) {
printk(KERN_INFO "Removing Module\n");
}
module_init( simple_init );
module_exit( simple_exit );
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Process Module");
MODULE_AUTHOR("SGG");
Part II –Iterating over Tasks with a Depth-First
Search Tree
The second portion of this project involves iterating over all tasks in the system using a depthfirst search (DFS) tree. Read and understand the purpose of this part of the project. Make the
following change to the program given in part I.
Change “bool partI = true ;” to “bool partI = false;”
 Compile and install this module. Take the screen shots of the output of your program
(saved in the kernel log)
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 Find the Linux command to display the process tree.
 Please discuss how different or similar the outputs of your program and Linux command.
 Provide a demonstration to convince me that that the program have indeed performed an
appropriate DFS iteration.
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