Bogdan PRICOP
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On 17 June 2016 at 11:35, Pranay Srivastava [off-list ref] wrote:

On Fri, Jun 17, 2016 at 3:41 PM, Martin Houry [off-list ref] wrote:

quoted

Hello mailing list!
I've read some code in the NFS4.1 client. I have trouble to access
variables in a list_head.

So I have :
(include/linux/sunrpc/xprt.h line 168)
struct rpc_xprt{
    .
    .

    struct rpc_wait_queue pending; /* requests in flight */
    .
    .
}

==>

struct rpc_wait_queue {
    .
    struct list_head        tasks[RPC_NR_PRIORITY]; /* task queue for
each priority level */
    .
}

The struct "list_head" is a classical  linked list. But How do I know
the type of the struct in this list?
I can maybe guess the struct in it :

struct rpc_task {}

But how can I be certain that "struct list_head tasks" contains some
"struct rpc_task"?

some magic value perhaps?

quoted

I'm new here, thank you for your help!
Martin

Hi Martin,

I think the main idea behind Linux kernel implementation of the linked
list (struct list_head) is to work with any kind of items which need
to be linked.

Please have a look at the below links which explain the internals of
Linux kernel list and its usage:
https://isis.poly.edu/kulesh/stuff/src/klist/
http://www.makelinux.net/ldd3/chp-11-sect-5

Thanks,
Bogdan