Re: [PATCH][RFC 23/23]: Support for zero-copy TCP transmit of user space data

Jeremy Fitzhardinge
2008-12-20T19:39:38Z

Evgeniy Polyakov wrote:
> Things should work fine, since pskb_expand_head() copies whole shared
> info structure (and thus will copy destructor), get all pages and then
> copy all pointers into the new skb, and then release old skb's data.
>
> So destructor for the pages should not rely on which skb it is called on
> and check if pages are about to be really freed (i.e. check theirs
> reference counter).
>

OK.

> __pskb_pull_tail() is tricky, it just puts some pages it does not want
> to be present in the skb, but it could be possible to add there
> destructor callback from the original skb with partial flag (or just
> having destructor with two parameters: skb and page, and if page is not
> NULL, then actually only given page is freed, otherwise the whole skb).
>

Yes, that doesn't sound too bad.

J