Re: nfnetlink_queue -- why linear lookup ?

[Florian Westphal <fw@strlen.de>]

alexandre.ferrieux@orange.com <alexandre.ferrieux@orange.com> wrote:
>   find_dequeue_entry(struct nfqnl_instance *queue, unsigned int id)
>   {
>     ...
>     list_for_each_entry(i, &queue->queue_list, list) {
>       if (i->id == id) {
>         entry = i;
>         break;
>       }
>     }
>     ...
>   }
> 
> As a result, in a situation of "highly asynchronous" verdicts, i.e. when we
> want some packets to linger in the queue for some time before reinjection,
> the mere existence of a large number of such "old packets" may incur a
> nonnegligible cost to the system.
> 
> So I'm wondering: why is the list implemented as a simple linked list
> instead of an array directly indexed by the id (like file descriptors) ?

Because when this was implemented "highly asynchronous" was not on the
radar.  All users of this (that I know of) do in-order verdicts.