list_process.c

#include<linux/init.h>
#include<linux/module.h>
#include<linux/kernel.h>
#include<linux/sched/task.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Preethi");
MODULE_DESCRIPTION("Linux Kernel Module for listing all processes");


char* get_state_string(long state)
{
    switch (state)
        {
        case TASK_RUNNING:
            return "Running";
        case TASK_INTERRUPTIBLE:
            return "Sleeping (Interruptible)";
        case TASK_UNINTERRUPTIBLE:
            return "Sleeping (Uninterruptible)";
        case __TASK_STOPPED:
            return "Stopped";
        case __TASK_TRACED:
            return "Tracing";
        case TASK_DEAD:
            return "Dead(Zombie)";
        case TASK_WAKEKILL:
            return "Wakekill";
        case TASK_WAKING:
            return "Waking";
        case TASK_PARKED:
            return "Parked";
        case TASK_NOLOAD:
            return "Noload";
        case TASK_NEW:
            return "New";
                case 1026://1024 OR 2
                        return "New (Interruptible)";
                case 1028://1024 OR 4
                        return "New (Uninterruptible)";
        default:
            return "Unknown";
    }
}


void fix_display(int i,int count) //implementing a for loop as recursion cause for not available in kernel modules
{
        if(i!=count)
        {
                printk(KERN_CONT "| ");
                fix_display(i+1,count);
        }
}

void traverse_process(struct task_struct *process,int count)
{
        struct task_struct *next_process;
        struct list_head *list;
        fix_display(0,count);
        printk(KERN_CONT "|_%s(PID:%d, PPID:%d) ---> %s\n",process->comm,process->pid,(process->parent)->pid,get_state_string(process->__state));
        list_for_each(list, &process->children)
        {
                next_process=list_entry(list,struct task_struct,sibling);
                traverse_process(next_process,count+1);
        }
}


static int __init InitModule(void)
{
        printk("Loading Kernel Module\n");
        printk("Process name, PID, PPID, State\n");
        traverse_process(&init_task,0);
        return 0;
}

static void __exit ExitModule(void)
{
        printk("Removing Kernel Module\n");
}

module_init(InitModule);
module_exit(ExitModule);