Subject: Re: [PATCH V5 2/6 net-next] netdevice.h: Add zero-copy flag in
 netdevice
From: Shirley Ma <mashirle@us.ibm.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: =?UTF-8?Q?Micha=C5=82_Miros=C5=82aw?= <mirqus@gmail.com>,
        Ben Hutchings <bhutchings@solarflare.com>,
        David Miller <davem@davemloft.net>,
        Eric Dumazet <eric.dumazet@gmail.com>, Avi Kivity <avi@redhat.com>,
        Arnd Bergmann <arnd@arndb.de>, netdev@vger.kernel.org,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org
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Date: Wed, 18 May 2011 10:00:28 -0700
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On Wed, 2011-05-18 at 19:51 +0300, Michael S. Tsirkin wrote:
> > > Yes, I agree.  I think for tcpdump, we really need to copy the
> data
> > > anyway, to avoid guest changing it in between.  So we do that and
> then
> > > use the copy everywhere, release the old one. Hmm? 
> > 
> > Yes. Old one use zerocopy, new one use copy data.
> > 
> > Thanks
> > Shirley
> 
> No, that's wrong, as they might become different with a
> malicious guest. As long as we copied already, lets realease
> the data and have everyone use the copy. 

Ok, I will patch pskb_expand_head to test it out.

Shirley

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