CODEWITHSUNDEEP
clinuxmultithreading
Jack Wang
Jack Wang

Reputation: 19

When I create a new userspace thead, it will appear on kernel process list?

I write a program name test.c. In this program, I created three thread by pthead_create. These thread named thread0, thread1, thread2 by prctl(PR_SET_NAME, name). The thread function code as follows:

    void *output(void *arg) {

            char *x = (char *) arg;
            char name[40] = "thread";
            strcat(name, x);
            prctl(PR_SET_NAME, name);
            while(1){
                    printf("%s\n", name);
                    sleep(10000);
            };
    }

Then I write a kernel module print.c which function is to print the each task_struct infomation int kernel process list. the code as follows:

    struct task_struct *task = &init_task;

    do{
            printk("%s\n", task->comm);
    }while((task=next_task(task)) != &init_task);

I run the program test.c first correctly and then insmod the module print.ko correctly. Unexpectly, I didn't find three threads' information. So, I want to ask that the thread created by pthread_create would not appear on kernel process list. is this opinion correct or not?

Upvotes: 0

Views: 127

Answers (1)

nos
nos

Reputation: 229304

A thread is also represented by a struct task in the kernel. You can iterate through each thread in a task by using e.g. the while_each_thread macro: 

struct task_struct *task = ...;
struct task_struct *t = task;
do {
    //use t
} while_each_thread(task, t);

Note: I don't know the proper locking, if any, around the task structs you need to be able to iterate through them like this.

Upvotes: 0

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