netdev - Re: [PATCH] TX_RING and packet mmap

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Date:	Wed, 15 Apr 2009 11:10:23 +0400
From:	Evgeniy Polyakov <zbr@...emap.net>
To:	Johann Baudy <johann.baudy@...-log.net>
Cc:	Herbert Xu <herbert@...dor.apana.org.au>, netdev@...r.kernel.org,
	"David S. Miller" <davem@...emloft.net>,
	Patrick McHardy <kaber@...sh.net>, jamal <hadi@...erus.ca>
Subject: Re: [PATCH] TX_RING and packet mmap

Hi Johann.

On Mon, Apr 13, 2009 at 01:31:14AM +0200, Johann Baudy (johann.baudy@...-log.net) wrote:
> So if my understanding is correct, there is no way to get original
> fragment address in destructor using skb fragment page/data.
> 
> Then,
> I can't use fragments due to skb_linearize
> I can't hide pointer into skb data due to skb_copy.
> I can't rely on other fields of skb.
> IMHO, using skb pointer requires too much cpu resources (parsing
> headers to identify the right buffer...)
> 
> So what can I do except using a new field?
> What do you think about adding a new field that is always linked to destructor?
> I mean adding a generic new field skb->destructor_arg.

It can work but do not place it into skb itself, but into shared area,
which is slab allocated and does not suffer from size restrictions.
You can also add shared-info destructor, which could be used by other

-- 
	Evgeniy Polyakov
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