Modify this system call to print the information for an arbitrary process. The system call takes a process pid (process id) as its argument and outputs the above information of this process.

HINT: You can start from the init process and iterate over all the processes. For each process, compare its pid with the target pid. If there is a match, return the pointer to this task_struct. A better approach is to use the pidhash table to look up the process in the process table. Linux provides many functions to find a task by its pid.

other useful methods:

1. for_each_process()

2. pid_task()

#include #include #include #include #include "processinfo.h" asmlinkage long sys_listProcessInfo(void) struct task struct *proces; for each process (proces) printk( "Process%s utime : %ld \ start time : %ld \ Process state: %ld " \ proces->comm, (long)task pid nr(proces), (long)proces->utime, \ (long)proces->start time, (long)proces->state, I \ if (proces->parent) printk( "Parent \ %s, \ process: %ld", PID Number: proces->parentComm, (long)task pid nr(proces->parent) printk("n ") return ; #include #include #include #include #include "processinfo.h" asmlinkage long sys_listProcessInfo(void) struct task struct *proces; for each process (proces) printk( "Process%s utime : %ld \ start time : %ld \ Process state: %ld " \ proces->comm, (long)task pid nr(proces), (long)proces->utime, \ (long)proces->start time, (long)proces->state, I \ if (proces->parent) printk( "Parent \ %s, \ process: %ld", PID Number: proces->parentComm, (long)task pid nr(proces->parent) printk("n ") return