LKD - Iterate over a process's children

["eric wyzerski" <ericwyzerski@xxxxxxxxxxx>]

Hi,

From the LKD books page 21, there is this code

struct task_struct *task;
struct list_head *list;

list_for_each(list, &current->children)
{
      task = list_entry(list, struct task_struct, sibling);
      /* task now points to one of current's children */
}

My question is why are we using sibling in the list_entry parameters? Our 
list variable points to children (under the task_struct) so why are we not 
using
task = list_entry(list, struct task_struct, children);?

Moreover, if we use it we can use the list_for_each_entry macro thats does 
exactly what we want
/**
* list_for_each_entry  -       iterate over list of given type
* @pos:        the type * to use as a loop counter.
* @head:       the head for your list.
* @member:     the name of the list_struct within the struct.
*/
#define list_for_each_entry(pos, head, member)                          \
       for (pos = list_entry((head)->next, typeof(*pos), member),      \
                    prefetch(pos->member.next);                        \
            &pos->member != (head);                                    \
            pos = list_entry(pos->member.next, typeof(*pos), member),  \
                    prefetch(pos->member.next))

So what I am missing?
Thanks

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