netdev - Re: Question about an assignment in handle

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Date:	Tue, 25 May 2010 08:20:38 -0400
From:	jamal <hadi@...erus.ca>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	Jiri Pirko <jpirko@...hat.com>, netdev@...r.kernel.org,
	davem@...emloft.net, kaber@...sh.net
Subject: Re: Question about an assignment in handle_ing()

On Tue, 2010-05-25 at 22:12 +1000, Herbert Xu wrote:

> It is guaranteed, it is illegal to hold onto the skb contents
> without the reference that comes from cloning an skb.

As i recall this was an issue. And the example i described earlier
would have tcpdump show edited contents coming out of eth0.

> The DHCP client may keep the AF_PACKET open even if there is no
> ongoing dialogue.

Ok ;-> Not running that dhcp client without looking at how it behaves.

> For ingress, the packet may have looped back from a virtual
> interface.  It may have been cloned on its way out of the virtual
> interface.

and i think this is where you and i ended last time we talked.

> Looking at ptype instead of checking whether the skb is cloned
> simply doesn't work in this case.

I will test in a few days - or if Jiri has the bandwidth i think i can
describe what to test (I have the relevant tests logged somewhere).

I apologize there may be some large latency of about a day before my
next response.

cheers,
jamal

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