I have a struct like
struct my_struct {
struct list_head queues[NB_QUEUES];
};
I would like to access at the first element of one of the queue (index is computed but I take 2 for the example, which is < NB_QUEUES) like the following (which works without arrays)
struct list_head t = list_first_entry(&foo->queues[2], struct my_struct, ???);
What am I supposed to do to obtain the first element of the queue at the index 2 ? I didn't find anything which compils
So, your code isn't very clear. Let's talk about a more generic example:
I have NB_QUEUES queues. I'm just going to store these as a global variable:
struct list_head queues[NB_QUEUES];
We'll want to make sure that our lists are initialized. We can do that statically with LIST_HEAD_INIT, or at runtime with INIT_LIST_HEAD.
int i;
for (i=0; i<NB_QUEUES; ++i)
INIT_LIST_HEAD(&queues[i]);
We can then push an object of type element into one of these queues:
struct element {
struct list_head list;
int data;
float more_data;
};
struct element *v = kmalloc(sizeof(*v), GFP_KERNEL);
v->data = 4;
v->more_data = 7.2;
list_add(&v.list, &queues[2]);
Later, we can then access the first element in the list.
struct element *q = list_first_entry(&queues[2], struct element, list);
The list argument is from the name of the member of struct element that we used when we inserted this object into the linked list.
