Re: several packets in a single buffer in Rx

[Tomas Winkler <tomasw@gmail.com>]

2011/5/16 Emmanuel Grumbach <egrumbach@gmail.com>:
> 2011/5/16 Michał Mirosław <mirqus@gmail.com>:
>> W dniu 16 maja 2011 14:59 użytkownik Emmanuel Grumbach
>> <egrumbach@gmail.com> napisał:
>>> 2011/5/16 Michał Mirosław <mirqus@gmail.com>:
>>>> 2011/5/16 Emmanuel Grumbach <egrumbach@gmail.com>:
>>>>> I would like to be able to deliver the same page several times to the
>>>>> stack without having the stack consume it before the last time I
>>>>> deliver it.
>>>>> Of course I would like to avoid cloning it.
>>>>
>>>> Just do get_page() on the page having another packet in it before
>>>> passing skb up.
>>>>
>>>
>>> I can see the path:
>>> __kfree_skb -> skb_release_all -> skb_release_data -> put_page
>>> put_page will free the page iff the _count variable reaches 0. Of course,
>>> _count is incremented by get_page.
>>>
>>> I will give it try.
>>>
>>> I understand that this will work regardless the order given to
>>> alloc_pages right ?
>>
>> Yes. Remember that if you put a lot of packets in a big-order page
>> then the memory will be freed only after all packets are freed.
>
> Sure. Thanks for the help.

How it is ensured that skb manipulation won't corrupt another packet
on the same page?

Thanks
Tomas