Understanding struct task list_head - c

Question

I have a struct my_struct I found a guide saying there is a linked list that is really easy to use, all I need to do is include a task list_head in my struct, but I don't understand how to traverse this list correctly because I don't know how the list is actually structured
[edit] How does this kernel link list actually work? Please explain.
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
try this outside of kernel:
#include "list.h"
// my list of elements
struct my_struct
{
struct task list_head;
}
I then declare the head of my list:
struct my_struct *head;
Memory is malloc for the head like this:
head = malloc(sizeof(*head));
I could use something like;
int count_elements_in_list()
{
int size = 0;
struct my_list *pos;
list_for_each(pos, head)
{
size++;
}
return size;
}
Can someone explain how this linked list actually works?

Answer 1

In your code, you included "module.h"; which is a standard include module for most all Linux kernel modules. The "module.h" file includes "list.h".
(These include headers can be found under /usr/src/linux/)
-
The 'list.h' kernel header file defines the -only- acceptable linked list implementation for the Linux kernel (as per kernel.org folks). In tern, 'list.h' includes 'types.h', which define the following:
struct list_head {
struct list_head *next, *prev;
}
In the code supplied to your question:
struct task list_head;
'struct task' contains a 'struct list_head' element. Then later:
list_for_each()
which is defined in 'list.h', which requires uses 'pos' and 'head' to iterate the list.